What’s In A PhD? A Basic Overview of Graduate School in STEM

What exactly does it mean to obtain a PhD? What is required, and what does the process look like? Maybe your relative or friend just said they’re going to graduate school, you’re struggling to understand all the strange nuances of academia. Or maybe you’re a PhD student who’s constantly trying to explain all of this to your curious friends and family. This article will provide a brief overview of PhD programs, with a focus on Science, Technology, Engineering, and Mathematics (STEM), to help everyone understand the wonderful strangeness that is a PhD.

What exactly is a PhD?

A PhD officially stands for “Doctor of Philosphy,” a term originating from ancient Greece when science and philosophy were considered overlapping fields. Nowadays, a PhD designates that an individual is a top-tier expert in their chosen field. People who have earned a PhD get to use the title “Dr.” It is important to distinguish a PhD from an MD. An MD is a Medical Degree and allows an individual to practice medicine as a doctor. In contrast, a PhD-holder cannot practice medicine; they are experts in academic research, rather than clinical treatment.

How long does a PhD take?

In Europe, most PhD programs last three to four years. In the U.S., five to six years is more typical. Many people are surprised by how long a PhD takes! After all, they’ve already spent at least four years on a Bachelor’s degree, and maybe a Master’s too, and now they’re signing up for even more yearsof education. This just shows how prestigious a PhD really is. It designates that you have spent many years of research to develop deep expertise in your field.

What is the difference between a PhD and a Master’s degree?

Most Master’s degree programs last one or two years. Typically, a Master’s program places greater emphasis on coursework than a PhD program would, though sometimes a Master’s degree may require a small research project culminating in a thesis. Additionally, most Master’s programs are unfunded and require that students pay tuition, whereas most PhD programs are funded (see next section). In some cases, students have to earn a Master’s degree prior to enrolling in a PhD program. In other cases, they can go straight into a PhD program out of undergrad. This depends on the field of STEM, as different disciplines have different requirements for PhD entry.

Are PhD students paid?

In STEM fields, yes, though the amout can vary greatly. In nearly all cases, PhD students receive a tuition waver and do not have to pay for any of their coursework. On top of this, PhD students are paid a modest stipend. This stipend is to compensate the student for their work in the research lab, which is truly a full-time job. In some cases, the stipend may not be enough to cover all living expenses, so the student will have to take out a loan or work a part-time job. It is also common for PhD students to work as Teaching Assistants (TAs) during a portion of their program in order to earn a higher stipend.

Do PhD students just take classes?

It is a very common misconception that PhD students just spend their time taking lots of classes. Classes are actually a very minor aspect of PhD programs and a much greater emphasis is placed on research. In fact, most PhD students finish up all their required classes within their first or second year of the program. They’ll also be working in a research lab part-time or full-time during this period. After they have finished their classes, they will spend the remaining years of their PhD working full-time in their lab. In many cases, PhD students will work long hours including weekends and evenings.

Do PhD students get the summers off?

Since most PhD students finish up their classes within the first couple of years, the concept of summer break doesn’t really exist for them, and they just continue working in their lab as normal over the summer. There also a few fields where it’s common for students to go intern at a company during the summers, though this is less common.

How do PhD students choose a lab?

This depends on the specific program. In some cases, the student will contact individual professors while applying to the graduate program based on an interest in their research. If the professor accepts them, the student will enroll and start working in that lab immediately. In other progarms, students complete “research rotations” during the first year of their PhD, where they spend anywhere from four to sixteen weeks completing a small research project in a lab. This essentially a trial period; it’s a chance for the student to see if they like the lab, and also for the professor to decide if they want to accept the student. Students may complete anywhere from two to six rotations before joining a lab.

Are PhD students considered scientists?

Depends who you ask! There is no standard definition of a scientist. Some people think you need to have completed a PhD and started your own lab to be considered a scientist. Personally, I think that a scientist is anyone who uses the scientific method to make new discoveries. Graduate students would certainly qualify as scientists under that definition.

What are the requirements for a PhD student to graduate?

If you ask a PhD student when they’re going to graduate, you might receive an annoyed response. This is because unlike other degree programs, the requirements to graduate from a PhD program are very vague, so their exact graduation date is often impossible to predict very far in advance. Essentially, a PhD student can graduate when their thesis committee determines they have made a sufficient contribution toward advancing research in their field. What exactly constitutes a “sufficient contribution” is up to the committee’s discretion; sometimes a scientific publication is required, sometimes the process is more wholestic. Once the committee has given approval, the student must write a dissertation that summarizes all of their research findings during their time in the program. This dissertation is a massive undertaking and may be hundreds of pages long. Additionally, the student must present an oral defense of their dissertation.

What happens after finishing a PhD?

There are lots of options! If a PhD graduate wants to get a job as a university professor, they will typically need to complete a “postdoc.” This means they will work full-time in a research lab (usually a different lab from where they earned their PhD) for anywhere from one to six years. A postdoc allows you to enhance your qualifications by publishing lots of scientific papers and establishing yourself as an independent scientist before applying for professor positions. Some people will complete two postdocs in order to get even more experience. However, there are many other paths besides becoming a professor. Some graduates will go work for a company. Sometimes they will become science communicators. They may even go into politics or law. It all depends on the interests and goals each PhD graduate.

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New Type of Brain Immune Cell Implicated in Alzheimer’s Disease

When most people think of the brain, we primarily imagine neurons. Neurons are the cells that use electrochemical signaling to directly control our thoughts, actions, and memories. However, neurons are not the only type of cell in the brain. Microglia are a type of immune cell that protects the brain against infections or injuries, among other important roles. One particularly important function of microglia is that they help to clear away amyloid-beta, a toxic protein that is believed to cause Alzheimer’s disease when it accumulates in the brain.

A group of researchers from the University of Pennsylvania wanted to learn more about the role microglia play in Alzheimer’s disease. Their work was published in the journal Acta Neuropathologica.

The researchers used a fairly new technique called single-nuclei RNA sequencing (snRNA-seq), which can reveal what genes are expressed in individual cells. They analyzed cells from the brains of deceased human Alzheimer’s disease patients. By analyzing their gene expression, they were able to categorize the microglia into four distinct groups. One of these groups, called amyloid-responsive microglia, may be important for avoiding Alzheimer’s disease by keeping toxic amyloid-beta at bay.

Next, the researchers wanted to focus on two particular genes called APOE and TREM2. Both of these genes may be involved in regulating how microglia respond to amyloid-beta. Previous studies have shown that genetic variants in APOE and TREM2 can influence the risk of developing Alzheimer’s disease.

The researchers looked at the brains of people who had versions of APOE and TREM2 that are associated with a higher risk of Alzheimer’s disease. These versions are known as risk variants. They found that individuals with risk variants in these two genes had fewer numbers of amyloid-responsive microglia in their brains. This result is exciting, as it provides a potential mechanism for how these genes influence the risk of Alzheimer’s via changing a particular category of microglia.

“These findings demonstrate that not all microglia respond the same to protein that builds up, or aggregates, in the brain,” says Dr. Aivi Nguyen, a former neuropathology and post-doctoral fellow who was the lead author on the paper. “Moreover, certain genetic risk factors are associated with specific types of microglial responses. Thus, neuroinflammation, or microglia getting revved up, may not be as binary as “good” or “bad.” Perhaps the answer is simply: it depends.”

Dr. Nguyen says she first became interested in this topic due to having a family member with Parkinson’s disease. “I did not realize how much I would enjoy the field, though,” she added. She also commented on the importance of a positive lab culture for her scientific success. “I have found this community to be incredibly supportive and encouraging, particularly as a woman neuropathologist.  An example of this positive culture is my mentor, Dr. Eddie Lee, who has helped me enormously and has advocated on my behalf on countless occasions.”

Dr. Nguyen and her coauthors plan to follow up on this study by investigating amyloid-responsive microglia in more detail. Their research could offer new insights into the role microglia play in Alzheimer’s disease and whether they could be a target for future therapeutics.

Elder Freedom’s Guide to Preventing Senior Falls

Guest author: Michael Longsdon has made it his mission to help locate resources, events, and engagement opportunities to help enrich the lives of seniors. He created Elder Freedom as an advocate for older adults in his community.  Through his site (http://elderfreedom.net/), he provides tips to seniors on how to downsize and age in place.

Blue and green "Elder Freedom" logo.

Notice: The information in this guide is not meant to treat, diagnose, or offer medical advice. Please consult your primary care doctor before engaging in any lifestyle changes.

As we advance into our senior years, emerging health conditions and physical changes, and even the prescription medications we use to treat those conditions each make falls more likely. In fact, falls are a leading cause of injury among senior adults. Even still, the fear of accidental falls shouldn’t have an impact in our lives.

Read our simple fall-prevention strategies below to learn more about preventing accidental falls.

Consult Your Physician

Before further reading, it’s important to consult your physician and get their professional opinion on which strategies are best for you.

Fall Prevention Questions for Seniors
How to Prevent Falls: 4 Proven Approaches
Preventing falls – what to ask your doctor

Keep Physically Active

Cardiovascular exercises such as walking, swimming, and biking are all great ways to keep our bodies healthy into their senior years.

The 7 Worst Exercises for Older Adults
Exercises for Seniors: The Complete Guide
14 Exercises for Seniors to Improve Strength and Balance
Exercise after age 70 – Harvard Health

Reduce Home Fall Hazards

By reducing as many fall hazards as possible at home, we can minimize our risk of accidental falls.

Home Design for Fall Prevention for Seniors
Check for Safety: A Home Fall Prevention Checklist (PDF)
9 Ways to Prevent Falling at Home

Do you have any more tips you think would help others avoid accidental falls? Let us know and we’d be happy to consider adding them here.

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Education promotes cognitive reserve against dementia… but only if you’re white.

A headshot of a young woman smiling at the camera. She has brown hair and is wearing a black and white striped shirt.

Guest author: Justina Avila-Rieger, PhD is a postdoctoral fellow of Neuropsychology in Neurology at the Gertrude H. Sergievsky Center and the Taub Institute for Research in Aging and Alzheimer’s disease at Columbia University. She completed her graduate training in clinical psychology, with an emphasis on neuropsychology and quantitative methodology, at the University of New Mexico and completed her clinical internship at the Baltimore VAMC. Her research examines racial/ethnic and sex/gender disparities in Alzheimer’s disease.

Experts have long suggested that keeping your brain active, especially through continued education, is a great way to protect our brains against dementia as we age. The idea is that education allows our brain to build up a “cognitive reserve,” which acts as a buffer to slow the onset of dementia. However, our recent paper found that this advice may only apply to White people.

Cognitive reserve is the ability to maintain thinking abilities even if the brain is damaged. Many brain functions are flexible and can compensate or change to make added resources available to cope with challenges. The term cognitive reserve is used to describe this disconnect, when cognitive function is not as impaired as would be expected given the level of brain degeneration.1 In other words, for people with a high level of cognitive reserve, their brains can show severe signs of degeneration, yet their dementia symptoms are much milder than would be expected.

A chart with AD neuropathology on the x-axis and cognitive status on hte y-axis. A green line, indicating a person with high cognitive reserve, has higher cognitive status even in the presence of neuropathology. A yellow line, indicating a person with low cognitive reserve, has lower cognitive status with the same level of neuropathology. A horizontal red line indicates incident dementia, showing that the person with higher cognitive reserve does not develop dementia until their neuropathology is much more severe than the person with low cognitive reserve.
This figure illustrates the idea of cognitive reserve. People with high cognitive reserve can have severe Alzheimer’s disease (AD) neuropathology, yet not experience any cognitive symptoms. Image source

Some indicators of life experiences and contexts, including years of education, are often used as proxies for cognitive reserve because they are associated with lower dementia risk and delayed age of dementia onset.2 However, the majority of cognitive reserve studies have been conducted in predominantly non-Latinx White (White) samples and do not consider racial or ethnic differences in educational experiences. (Note: Latinx is the gender-neutral form of Latino/Latina and refers to people originating from Latin America.)

In our recent study, we tracked a community of 1,553 White, Black, and Caribbean-born Latinx  older adults over time.3 We found that White individuals with more years of education had slower cognitive decline compared with White individuals with fewer years of education, despite having the same level of brain degeneration. In other words, greater years of education buffered the effects of brain degeneration for White people. However, for Black and Latinx individuals, years of education did not protect cognitive function against the effects of brain degeneration.

Why might the protective effects of education differ across racial/ethnic groups? My colleagues and I suggest that racism is likely to be the primary underlying reason that having more years of school contributed to cognitive reserve in Whites, but not among Black or Latinx participants. Most Black older adults in the United States were born and raised in the South,4 where Jim Crow laws enforced segregation and limited opportunities within education, health care, housing, and the labor market.5 Across all U.S. states, both before and after Brown v. Board of Education, racist policies and residential segregation forced Black children to attend underfunded schools that had large student/teacher ratios, shorter term length, lower teacher salaries, and inadequate budgets for supplies and school buildings.6 These structural inequalities contribute to lower returns from education among Blacks compared to Whites.7

Similarly, older Caribbean-born Latinx who grew up outside of the United States also had fewer opportunities to attend school and/or received a poor quality of education.8,9 Years of education may not adequately represent the effect of life-course experiences that contribute to cognitive reserve across all racial/ethnic groups. As a result, the contribution of years of education to cognitive reserve is reduced for racial/ethnic minorities.

Even if educational experiences were equivalent across groups, structural racism impacts adult opportunities that might contribute to cognitive reserve across racial/ethnic groups. Racism in the labor market has served to counteract the benefits of schooling for Black Americans. For example, Black men continue to have lower employment rates than White men even if they have the same educational attainment10. It is also possible that the protective effects of education are reduced by stress associated with institutional racism and discrimination.

Do these findings mean that Black and Latinx individuals do not have cognitive reserve? Absolutely not. Rather, these findings suggest that years of education is just not a good indicator of the life-course experiences that contribute to cognitive reserve in Black and Latinx people. Several studies have demonstrated that measures of school quality may be a better indicator of educational experiences in racial/ethnic minorities than years of education.7–9,11,12 There is also evidence that early life educational policies13 influence later life dementia risk and cognitive decline, above and beyond educational attainment. There are also other early life experiences14 (e.g., childhood socioeconomic status, neighborhood factors) that may better indicators of cognitive reserve among Blacks and Latinx.

Overall, our findings provide more evidence that social inequalities across the lifecourse have an impact on racial and ethnic disparities in Alzheimer’s disease. Inequalities in school opportunities, including school segregation and limited governmental investment in schools that served Black and Latinx children, as well as racial discrimination in occupation, housing, criminal justice, and healthcare can help to explain why there are diminished “brain health” returns to educational attainment for Black and Latinx older adults. Considering that Black and Latinx individuals are 2 to 3 times more likely to develop Alzheimer’s disease than White individuals,15 more research is needed to understand the life-course factors that contribute to cognitive reserve. Such work may lead to identification of factors that may narrow racial/ethnic inequalities in the onset and progression of Alzheimer’s disease.

Sources:

  1. Mungas D, Gavett B, Fletcher E, Farias ST, DeCarli C, Reed B. Education amplifies brain atrophy effect on cognitive decline: Implications for cognitive reserve. Neurobiol Aging. 2018;68:142-150. doi:10.1016/j.neurobiolaging.2018.04.002
  2. Amieva H, Mokri H, Le Goff M, et al. Compensatory mechanisms in higher-educated subjects with Alzheimer’s disease: a study of 20 years of cognitive decline. Brain J Neurol. 2014;137(Pt 4):1167-1175. doi:10.1093/brain/awu035
  3. Avila JF, Arce Renteria M, Jones RN, et al. Education differentially contributes to cognitive reserve across racial/ethnic groups. Alzheimers Dement.
  4. Ruggles S, Sobek M, Alexander T. Integrated Public Use Microdata Series: Version 3.0. Minnesota Population Center; 2004.
  5. Barnes LL, Bennett DA. Alzheimer’s disease in African Americans: Risk factors and challenges for the future. Health Aff. 2014;33(4):580-586.
  6. Hedges LV, Laine RD, Greenwald R. Does Money Matter? A Meta-Analysis of Studies of the Effects of Differential School Inputs on Student Outcomes. Educ Res. 1994;23(3):5-14. doi:10.3102/0013189X023003005
  7. Manly JJ, Jacobs DM, Touradji P, Small SA, Stern Y. Reading level attenuates differences in neuropsychological test performance between African American and White elders. J Int Neupsychological Soc. 2002;8:341-348.
  8. Sisco S, Gross AL, Shih RA, et al. The role of early-life educational quality and literacy in explaining racial disparities in cognition in late life. J Gerontol B Psychol Sci Soc Sci. 2013;70(4):557-567.
  9. Manly JJ, Jacobs DM, Sano M, et al. Effect of literacy on neuropsychological test performance in nondemented, education-matched elders. J Int Neupsychological Soc. 1999;5:191-202.
  10. McDaniel A, DiPrete TA, Buchmann C, Shwed U. The black gender gap in educational attainment: historical trends and racial comparisons. Demography. 2011;48(3):889-914. doi:10.1007/s13524-011-0037-0
  11. Manly JJ, Byrd D, Touradji P, Sanchez D, Stern Y. Literacy and cognitive change among ethnically diverse elders. Int J Psychol. 2004;39(1):47-60.
  12. Arce Renteria M, Vonk JMJ, Felix G, et al. Illiteracy, dementia risk, and cognitive trajectories among older adults with low education. Neurology. 2019;93(24):2247-2256.
  13. Dementia risk likely measurable among adolescents, young adults. Accessed August 27, 2020. https://www.healio.com/news/psychiatry/20200730/dementia-risk-likely-measurable-among-adolescents-young-adults
  14. Xu H, Yang R, Qi X, et al. Association of Lifespan Cognitive Reserve Indicator With Dementia Risk in the Presence of Brain Pathologies. JAMA Neurol. Published online July 14, 2019. doi:10.1001/jamaneurol.2019.2455
  15. Facts and Figures. Alzheimer’s Disease and Dementia. Accessed August 27, 2020. https://www.alz.org/alzheimers-dementia/facts-figures

Note: This post was originally titled “Education protects against dementia… but only if you’re white.” This is inaccurate, and the title has been corrected accordingly.

Report Finds COVID-19 Has Disproportionately Impacted Dementia Patients

A recent report from the International Long-Term Care Policy Network found that the COVID-19 pandemic had a disproportionate negative impact on people living with dementia. The authors collected data from 9 countries: the United Kingdom, Spain, Ireland, Italy, Australia, the United States, India, Kenya and Brazil.

They found that people with dementia accounted for between 29% and 75% of COVID-19 deaths in these countries. Many of these deaths are linked to care homes. Containing the spread of COVID-19 in care homes is very challenging due to the close living conditions, as well as the difficulty of enforcing mask-wearing among residents with dementia.

In order to contain the spread of the virus, many care homes have implemented social distancing measures. However, many of these adjustments could have contributed to worse patient outcomes, as an abrupt change in routine can greatly impair quality of life for dementia patients and lead to physical deterioration.

For example, personal protective equipment (PPE) such as masks, which can cause distress to dementia patients by making it difficult for them to recognize or communicate with their caregivers. In addition, many care homes experienced PPE shortages, causing widespread COVID-19 infections. Furthermore, only half of the care homes surveyed had the proper facilities to isolate a resident who tested positive for COVID-19.

The rapid spread of COVID-19 in care homes led to many staff members testing positive for the virus. As a result, staff shortages were common and residents were often left alone without assistance for long periods of time. One study found that this chronic isolation was an even higher cause of mortality among dementia patients than the virus itself, often due to dehydration.

In addition, many care homes have banned family visits and reduced contact between residents in order to contain the spread of the virus. These measures have caused many patients to experience loneliness, confusion, or depression. Many care homes have not implemented alternative forms of communication, such as video calls or phone calls.

The impact of COVID-19 is not limited to care homes. Studies have found that dementia patients living at home have experienced worse cognitive symptoms, while caregivers report increased stress and burnout. Many sources of support and respite for dementia caregivers are no longer available during the pandemic. In addition, many centers that offer therapies for dementia patients, such as cognitive stimulation therapy or speech and langauge therapy, have closed.

The authors also noted that ageism and ableism have both worsened health outcomes for dementia patients. Ageism is prejudice against people based on their age, while ableism is prejudice against disabled people. Both of these factors compound on each other for dementia patients. As a result, with many ICUs overrun by COVID-19 cases and short on beds and supplies, dementia patients are often denied treatment in favor of younger patients or individuals without a cognitive disability. The lives of dementia patients, and elderly people general, are seen as less valuable by many people, and thus their deaths are downplayed during discussions of the pandemic.

The current situation is certainly harmful for dementia patients and their caregivers. However, the report offered several suggestions for how to keep patients safe from the virus while promoting social interaction. These include increased use of video calling between care home residents and their families, redesigning activities for social distancing (such as hallway bingo), and allowing family visits through glass windows.

They also emphasized that governments must remedy the PPE shortage in order to protect the staff and residents in care homes. Care home staff should also be financially compensated at higher rates due to the huge emotional and physical burden of their position. Finally, the healthcare and elder care systems must be redesigned in order to prevent a future pandemic from having this kind of impact on dementia patients.

For individuals with dementia and their caregivers, here are some helpful resources related to COVID-19:

 

[Note to readers: Due to the demands of graduate school, I have not been publishing articles nearly as frequently as I used to. I am planning to resume a more regular publishing schedule moving forward, though I likely will not be as prolific as I was in the past. Thank you for your patience and for sticking with me.]

 

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A Causal Link Between Alzheimer’s Disease and Cancer

Though they may seem like unrelated diseases, cancer and Alzheimer’s disease are more closely linked than you’d expect. As I’ve discussed previously on the blog, scientists have been aware for nearly 15 years that these two conditions are inversely correlated. In other words, cancer survivors have a lower risk of later developing Alzheimer’s disease, and vice versa.

According to one meta-analysis, Alzheimer’s patients have a 42% reduced risk of developing any kind of cancer in their lifetime, while cancer survivors have a 37% reduced risk of Alzheimer’s disease. Notably, this correlation is not caused by decreased life expectancy or different lifestyle choices, as the analysis took these factors into account in their calculations.

While those numbers look pretty convincing, we must be careful when interpreting the results of observational studies. A scientist’s favorite mantra is “correlation does not imply causation.” In other words, based on these studies alone, we have no way to know whether cancer directly protects against Alzheimer’s disease, Alzheimer’s directly protects against cancer, or some unknown third factor is linking the two diseases indirectly. We can’t determine a causal relationship from observation alone.

However, a recent study published in Scientific Reports attempts to address this dilemma. Researchers from the University of Cambridge used a technique called Mendelian randomization to determine causality. Essentially, this involves searching for genetic variants that are known to increase the risk of cancer, and then determining whether those same variants also decrease the risk of Alzheimer’s. By probing at the genetic level, this technique allows researchers to directly determine whether cancer is protective against Alzheimer’s.

Using data from public repositories, the authors determined that several genetic variants involved in cancer risk are protective against Alzheimer’s. Overall, a 10-fold (1000%) higher genetic risk for developing cancer results in a 2.5% reduced risk of Alzheimer’s. That may seem like a small reduction, but keep in mind that this represents only the genetic component of risk. Since both cancer and Alzheimer’s are complex diseases and heavily influenced by non-genetic factors, these numbers encapsulate only a small portion of an individual’s overall risk.

Importantly, this study is the first to show a causative link (rather than merely a correlation) between Alzheimer’s disease and cancer. The study’s lead author, Sahba Seddighi, stated, “Our results offer novel possibilities for targetable pathways in Alzheimer’s disease—which remains without a cure, despite a rapidly growing aging population—and call for a deeper understanding of the underlying mechanisms behind this relationship.”

So what does this link really mean? In a way, it makes some intuitive sense: cancer is the result of uncontrolled cell growth and proliferation, while Alzheimer’s is associated with cell death and degeneration. But what genetic interactions and cell signaling pathways are involved remains unknown.

In the meantime, by shedding new light on the genetic underpinnings of Alzheimer’s, the study brings a new insight to the field, which will hopefully bring scientists one step closer to finding a cure.

 

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Ultrasound and Microbubbles May Be Used to Treat Alzheimer’s Disease

Alzheimer’s disease, the most common form of dementia, is characterized by the buildup of toxic, sticky plaques inside the brain. These plaques are made of a protein called amyloid-beta. Although hundreds of drug candidates that try to remove amyloid-beta from the brain have been tested in clinical trials, these have been a resounding failure (see “Where’s our cure to Alzheimer’s disease?”). This has led scientists to try out new methods for treating the disease.

One of the most intriguing ideas for treating Alzheimer’s is to use ultrasound. Ultrasound uses high-frequency sound waves outside the range of human hearing. These sound waves can pass through soft tissues but bounce off of denser things such as bone, which is how ultrasound can generate the image of a fetus during pregnancy.

Ultrasound has many uses outside of imaging. One recent techniques involves injecting the patient with tiny “microbubbles.” When hit with an ultrasound pulse, the microbubbles expand and contract. This allows them to gently press against the blood vessel walls without damaging them.

The microbubble ultrasound technique has an interesting effect inside the blood-brain barrier (BBB). The BBB is a complex structure that surrounds blood vessels inside the brain. It prevents harmful toxins and pathogens from entering the brain, but can also make it difficult for waste products (including amyloid-beta) to be cleared away.

blood-brain-barrier_med.jpeg

The cells surrounding blood vessels in the brain, known as the blood-brain barrier, prevent large molecules from passing through. Image Source

When microbubbles inside the brain’s blood vessels expand, they can temporarily open the BBB. This not only allows for enhanced clearance of waste products, but also activates many immune pathway in the brain that further assist with this process.

Early experiments involving mice have been encouraging. In 2013, 2014, and 2015, three different research groups found that mice that were genetically engineered to develop Alzheimer’s disease showed improvements after ultrasound/microbubble treatments. This included reduced levels of amyloid-beta, improved spatial memory, and more newborn neurons inside the hippocampus, a part of the brain associated with memory.

Several human trials involving ultrasound are currently being planned or in progress. One small trial of five subjects found that the ultrasound device could safely and reversibly open the BBB. However, we still need to wait for more results to come out before we’ll know whether this strategy is effective for treating Alzheimer’s.

It also remains to be seen whether ultrasound may come with any unforeseen consequences. It’s possible that opening the BBB could allow certain immune cells or pathogens to enter the brain, creating an opportunity for autoimmune reactions or brain infections. Despite the potential risks, researchers remain hopeful that ultrasound could offer a noninvasive means for treating Alzheimer’s disease in the future.

 

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Why Are Women Twice as Likely to Get Alzheimer’s Disease?

Of the more than 5 million Americans living with Alzheimer’s disease, nearly 2/3 of them are women. A woman in her 60s has a 1 in 6 chance of later developing Alzheimer’s, compared to only 1 in 11 for a man. What is the cause for this sex imbalance?

A major player in this question is the APOE gene (see The Genetics of Alzheimer’s Disease for more detail). This gene comes in three different forms: APOE2, APOE3, and APOE4. Each of us inherits two copies of this gene (one from each parent). If you have one copy of APOE4, your risk of Alzheimer’s increases threefold, while having two copies of APOE4 increases your risk by fifteen times. For reasons that remain unclear, the APOE4 allele seems to be a stronger risk factor for women than men, which could help to explain the difference in Alzheimer’s prevalence.

Some lines of research suggest that sex hormones may also play a role. Specifically, reduced estrogen levels, which commonly occur during menopause, are associated with increased risk of Alzheimer’s. Several studies have shown that women with Alzheimer’s tend to have lower estrogen levels in their brains. Pregnancy also reduces lifetime exposure to estrogen, which may explain why women who have had biological children have a higher risk of dementia than women without biological children. Similarly, women who have had a hysterectomy or oophorectomy (removal of the uterus or ovaries), which can induce menopause at an earlier age, also have an increased risk of dementia.

menopause-s2-chart

A woman’s estrogen levels decrease as they approach menopause, which may be linked to their increased risk for Alzheimer’s. Image Source

So if low estrogen is a risk factor for Alzheimer’s, could estrogen replacement therapy (ERT) combat this? ERT is commonly used as a treatment for menopausal symptoms such as hot flashes, as well as to reduce the risk of osteoperosis. Clinical trials investigating the effects of ERT on dementia have had mixed results. There is some evidence to suggest that it may only be protective if women begin treatment within the first few years of menopause. So far, the jury is still out on whether these therapies could be beneficial for preventing dementia. There are also some notable risks associated with ERT, including a higher chance of breast cancer.

What about male sex hormones? Similarly to women, men with Alzheimer’s disease tend to have lower levels of testosterone than normal. So if the loss of both sex hormones can increase the risk of Alzheimer’s, why do we see a much higher prevalence in women? One theory is that it relates to how quickly these hormones are lost. The menopause transition usually takes around four years, while male reproductive aging takes place gradually over several decades. Perhaps the abruptness of estrogen loss in menopause is responsible for the higher risk of dementia.

Another important difference between men and women lies in their risk for other dementia-related diseases. Women are more than twice as likely as men to have depression, and they also have a higher risk of insomnia and fragmented sleep. All of these conditions are linked to an increased risk of Alzheimer’s. In addition, women have historically been granted less access to education, employment, and physical exercise, which can be protective against dementia. This is particularly true for women who grew up in the mid-20th century and are now reaching their elderly years.

In conclusion, there’s still a lot we have to learn about why women are more prone to Alzheimer’s disease than men. In the meantime, both women and men can still greatly reduce their overall risk of Alzheimer’s through lifestyle changes. See 10 Tips to Reduce Your Dementia Risk to learn more.

 

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Why People with Down Syndrome are at High Risk for Alzheimer’s Disease

Down syndrome is a neurodevelopmental disorder caused by inheriting an extra copy of chromosome 21. The most common symptoms include intellectual disability, unusual facial features, and heart defects. About 1 in 700 babies is born with this condition.

The average lifespan for a person with Down syndrome is 60 years. Sadly, the last few years of their lives are often lost to Alzheimer’s disease. Nearly two-thirds of Down syndrome patients are diagnosed with Alzheimer’s before the age of 60. This is far higher than the general population, of whom less than 1% develop Alzheimer’s this early in life.

The reason for this greatly elevated risk of Alzheimer’s disease comes down to genetics. While chromosome 21 contains hundreds of different genes, a single gene is believed to cause Alzheimer’s disease in Down syndrome patients: APP. This gene encodes a protein called amyloid-beta. Amyloid-beta is a toxic, sticky protein that can clump together and accumulate inside the brain, which is believed to be a major contributing factor to Alzheimer’s disease.

Because of their extra copy of chromosome 21, people with Down syndrome produce more amyloid-beta than normal. Nearly 100% of Down syndrome patients start to develop amyloid-beta aggregates in their brains during their 40s. This puts them at a very high risk of developing Alzheimer’s at an early age.

After the practice of institutionalizing people with Down syndrome became less common, their life expectancy improved dramatically, up from only 25 in 1983 to 60 today. However, this means that more Down syndrome patients are living long enough to develop Alzheimer’s disease, which is a frightening prospect to these individuals and their families.

Despite the troubling statistics, there is hope for people with Down syndrome. Many neuroscientists believe that early intervention is key for preventing Alzheimer’s disease. However, ethical standards make it difficult to administer treatments to people before we know for sure that they’ll develop a disease, particularly if those treatments come with certain risks. This makes it challenging to test out new preventative therapies for Alzheimer’s disease.

Because of the very high rate of Alzheimer’s disease among Down syndrome patients, they may be an exception to this rule. New drug candidates can be tested on these individuals beginning early in life, which may prove to be a more effective strategy for preventing Alzheimer’s. While only time can tell whether these treatments will prove beneficial, many remain hopeful for the future of research.

 

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Interview with Alzheimer’s researcher, blogger, and advocate Maya Gosztyla

Check out Global Health Aging’s interview with AlzScience creator, Maya Gosztyla!

GLOBAL HEALTH AGING

Maya Gosztyla is the creator of AlzScience. Her passion for Alzheimer’s disease began at a young age when her grandmother was diagnosed with vascular dementia following a stroke. She currently works in a lab at the National Institutes of Health, where she’s researching a rare neurodegenerative disorder called Niemann-Pick Disease. In addition to her love of research, Maya has a passion for science writing and hopes to continue educating the public about the ways we can keep our brains healthy as we age. We are excited to interview Maya about her research, fighting Alzheimer’s and the role of diet in brain health.

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