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.

 

Enjoy this post? Help it to grow by sharing on social media!
Want more? Follow AlzScience via email, Facebook, or Twitter!

4 thoughts on “Ultrasound and Microbubbles May Be Used to Treat Alzheimer’s Disease

  1. Dan

    I’ve read many articles on Dementia/Alzheimer’s regarding the plaque that causes it, but have not seen anything that indicates the source of the plaque or what causes it. Maybe I’ve just missed that information. Has anyone heard what causes the plaque, or have the researchers not identified that source yet? Thanks in advance for this information.

    Like

    Reply
    1. AlzScience Post author

      Hi Dan, thanks for your comment! We know that the plaques are made of a protein called amyloid-beta, but researchers still aren’t sure what causes it to accumulate in some people. In fact, a growing body of research suggests that amyloid-beta may not be the root cause of the disease at all, and instead it’s more of a side effect. There’s a lot that still remains to be discovered.

      Like

      Reply
  2. Alice Gosztyla

    Very interesting, and hopeful to hear that scientists are pursuing such different ways to treat or prevent Alz.

    Alice G.

    Like

    Reply

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s