Chronic Disease Harvey A. Friedman Center for Aging

Unraveling the mystery: Understanding Alzheimer’s disease and its impact

Written by Maya Samih, BS candidate at Saint Louis University, and participant in the 2023 Institute for Public Health Summer Research Program

Often, dementia and Alzheimer’s disease are mistakenly used interchangeably, overlooking the fact that dementia encompasses more than just Alzheimer’s disease (AD). Gaining a deeper understanding of Alzheimer’s disease and the aging process in individuals with AD could bring us a step closer to taking preventative measures or, at the very least, help slow down its progression.

Dementia is a broad classification encompassing the decline in cognitive abilities, while AD is a specific disease with certain characteristics. AD is caused by the accumulation of specific proteins in the brain, like amyloid beta plaques and tau tangles, which ultimately lead to brain cell death. According to Justin Long, MD, PhD, an Assistant Professor in Neurology, in the Division of Aging and Dementia, AD is worth understanding as it is currently the 5th leading cause of death in the states. Expanding my knowledge on this topic, I attended a seminar with Long, who discussed the brain abnormalities associated with AD, the clinical features of AD, and its impact on Down Syndrome patients.

Brain Abnormalities
Some brain abnormalities are evident in the pre-clinical stages of AD before any symptoms may become apparent to the individual. Alzheimer’s disease is characterized by the presence of a sticky substance called amyloid beta plaque that builds up in the brain and twisted tangles in neurons called neurofibrillary tangles. These plaques and tangles ultimately lead to cell death and deterioration of brain function. Health professionals have studied the brain scans of AD patients, and it was clear that due to neuron loss, the brain volume in an AD patient is significantly smaller than that of a healthy patient. Long also explained that there are currently no medications to treat AD, but there are medications to remove amyloid beta plaque from the brain, decreasing the progression of cognitive symptoms.

Image: Mayo Clinic

The image above shows the difference between a healthy brain and an AD brain. It is clear that there is a loss of neurons, and the volume of the AD brain is smaller than the healthy brain. This image is a good representation of some of the changes in the brain that occur.

Clinical Features of AD
Clinical features occur when the cognitive decline becomes evident, and symptoms start to show.  Usually, clinical features develop in the order as follows.

  1. Gradual onset and progression
  2. Problems start interfering with everyday functions
  3. Short-term memory deficits
  4. Personality changes, disorientation, and impaired judgment

Impact on Down Syndrome Patients
One of the goals of my current research involves finding a non-invasive method to identify pre-clinical AD in Down Syndrome patients in hopes of finding ways to slow the progression of this disorder. Almost all individuals aging with Down Syndrome will develop AD around the age of 40. Long explained that this is true because the amyloid precursor is created on chromosome 21, and DS patients have three copies of chromosome 21. Therefore, chromosome 21 produces extra amyloid precursor, so more amyloid beta plaque is produced and flows into the brain.

In my future career, I hope to advocate for advancements in research and treatment concerning Alzheimer’s disease. According to the Alzheimer’s Association, over 6 million Americans live with AD. Together, we can unravel this mystery affecting the lives of millions in our community.