Tag Archives: eye

Macular Degeneration: Alzheimer’s Disease of the Eye?

Macular degeneration affects more than 10 million Americans, making it the leading cause of vision loss. It occurs when, for reasons that aren’t entirely understood, the central region of the retina (known as the “macula”) begins to deteriorate. The disease is considered incurable and usually occurs in people over the age of 55. Smokers and individuals of Caucasian decent are at an increased risk, as well as anyone with a family history of the disease.

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This animation from the American Macular Degeneration Foundation shows the loss of central vision that occurs with this disease.

Surprisingly, there are many parallels between macular degeneration and Alzheimer’s disease. Though the two conditions may seem unrelated, both are believed to be caused by the buildup of a toxic protein called amyloid-beta. In Alzheimer’s disease, amyloid-beta plaques accumulate in the brain, while in macular degeneration, amyloid-beta forms fatty deposits behind the retina called “drusen.” Plaques and drusen appear to have similar composition of proteins and fats, and utilize the same mechanisms to damage surrounding tissue.

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Diagram of a normal eye and an eye with macular degeneration. Image Source

The similarities between these two diseases don’t end there. Older people with macular degeneration are three times as likely to have cognitive impairment, suggesting that the same processes leading to amyloid-beta accumulation in the retina could also be occurring in the brain. This makes sense, since the retina and the brain are both part of the central nervous system. Additionally, several mouse models of Alzheimer’s disease exhibit amyloid-beta buildup in both the brain and the retina, further cementing the link between the two conditions.

The emerging connection between Alzheimer’s and macular degeneration has several important consequences. If amyloid-beta buildup in the retina could be a sign of a similar process happening in the brain, it raises the possibility that eye exams could serve as a non-invasive method to screen people for Alzheimer’s disease. Clinical trials for this idea are still ongoing, but the early results seem encouraging. These eye exams could potentially allow for earlier Alzheimer’s diagnosis or a lower risk of misdiagnosis.

This relationship also suggests that people with Alzheimer’s disease could be at a greater risk of macular degeneration, or vice versa. If you or a loved one is experiencing dementia, it’s recommended to minimize the risk of macular degeneration by receiving regular eye exams, protecting the eyes from sunlight, and maintaining a healthy diet.

 

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Research Highlights from the Alzheimer’s Association International Conference

This year’s Alzheimer’s Association International Conference took place July 22-28 in Toronto. The meeting brings some of the world’s leading Alzheimer’s researchers together to discuss their latest findings. I’ve compiled brief descriptions for some of the most exciting research presented at the meeting.

Mental Stimulation Greatly Influences Risk of Dementia

An unhealthy “Western” diet is associated with an increased risk of many health problems, including dementia. However, results presented at AAIC suggest mental stimulation in the form of higher education, a cognitively complex job, and/or social engagement can reduce the risk of cognitive decline in elderly adults, even those with a poor diet. Additionally, the highly-publicized ACTIVE study found that elderly subjects who participated in 10 years of regular cognitive training (similar to brain-training games like Luminosity) had a 48% reduced risk of dementia during the course of the study. Read more

Symptoms Checklist May Aid in Earlier Diagnosis of Alzheimer’s

Researchers have defined a new later-life neuropsychiatric condition called Mild Behavioral Impairment (MBI), which may be a precursor for Mild Cognitive Impairment and/or dementia later in life. The symptoms associated with MBI are grouped into five broad categories: mood, impulse control, apathy, social appropriateness, and psychosis. A recent study found that more than 80% of elderly adults at a memory clinic displayed at least one symptom of MBI, and that the symptoms were associated with increased caregiver burden. The researchers plan to refine the MBI checklist to be applicable to younger, non-demented subjects. Read more

Alzheimer’s Patients Receiving Treatment Have Reduced Mortality and Financial Burden

The medications for Alzheimer’s disease currently on the market can decrease the rate of cognitive decline but do not slow the overall progression of the disease. However, new results suggest that receiving treatment can reduce both mortality rates and medical costs for Alzheimer’s patients post-diagnosis. Patients who took dementia medications had a 28% reduced risk of dying during the approximately 2-year course of the study, and also paid more than $1,000 less each month in healthcare costs. Read more

High Cost of Preventable Hospitalizations Among Alzheimer’s Patients

A recent study shows that 1 in 7 hospitalizations among individuals with Alzheimer’s and related dementias is potentially preventable. These include hospital visits as a result of acute conditions like infection or dehydration, as well as chronic diseases including diabetes, cardiovascular disease, or respiratory illness. In total, preventable hospitalizations of dementia patients cost Medicare $2.58 billion dollars during 2013. Read more

Smell and Eye Tests May Predict Cognitive Decline

Two of the first brain regions affected by Alzheimer’s disease are the olfactory (smell) and visual systems. Studies presented at AAIC showed that neurodegeneration of the optic nerve or retina could be an effective predictor for the development of Alzheimer’s. Two other labs found that low scores on the University of Pennsylvania Smell Identification Test were associated with cognitive decline and dementia. Read more

Promising Anti-Tau Drug Fails in Clinical Trials

Alzheimer’s is characterized by the buildup of two toxic proteins in the brain: beta-amyloid and tau. After hundreds of drugs targeting beta-amyloid failed in clinical trials, researchers have recently begun to look into anti-tau drugs instead. Unfortunately, a promising anti-tau drug called LMTM failed in phase 3 of clinical trials. Apart from in a small subgroup of participants, the drug did not improve cognitive or neurological symptoms better than a placebo. Additionally, 80% of subjects experienced at least one adverse side effect. Read more

Men with Dementia are More Likely to Be Misdiagnosed than Women

It’s a commonly-held belief that women are at a greater risk of Alzheimer’s than men. However, it’s possible that innacurate diagnoses may contribute to this discrepancy (see Is It Really Alzheimer’s? 10 common misdiagnoses you should know about). A study of more than 1600 postmorten brains found equal rates of Alzheimer’s among men and women. Men typically have a younger age of onset and are more likely to exhibit atypical symptoms, increasing the risk of misdiagnosis. Another postmortem brain study found that across genders, approximately 10% of Alzheimer’s diagnoses were incorrect, with the true cause of memory loss usually being vascular dementia. Read more

Reducing Dependence on Antipsychotics in Dementia Care

Multiple studies have demonstrated that prescribing antipsychotics to dementia patients can accelerate the rate of cognitive decline and death. Nonetheless, this remains a common practice for treating the symptoms of dementia. In a recent study, nurses in 60 long-term care facilities were trained to manage patients’ dementia symptoms without the need for drugs. The patients’ doses of antipsychotics were incrementally reduced until they were eliminated. Most of the subjects were able to successfully cease antipsychotic use after a one-year follow-up. Read more

 

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