Alzheimer's is a type of dementia that causes problems with memory, thinking and behavior. Symptoms usually develop slowly and get worse over time, becoming severe enough to interfere with daily tasks.
|Figure 1: Older people are susceptible to Alzheimer's (fig. source: Google)|
Alzheimer's is not a normal part of aging. The greatest known risk factor is increasing age, and the majority of people with Alzheimer's are 65 and older. But Alzheimer's is not just a disease of old age. Approximately 200,000 Americans under the age of 65 have younger-onset Alzheimer’s disease (also known as early-onset Alzheimer’s). Alzheimer's worsens over time. Alzheimer's is a progressive disease, where dementia symptoms gradually worsen over a number of years. In its early stages, memory loss is mild, but with late-stage Alzheimer's, individuals lose the ability to carry on a conversation and respond to their environment. Alzheimer's is the sixth leading cause of death in the United States.
Cause of Alzheimer’s Disease
The brain has 100 billion nerve cells (neurons). Each nerve cell connects with many others to form communication networks. Groups of nerve cells have special jobs. Some are involved in thinking, learning, and remembering. Others help us see, hear and smell. To do their work, brain cells operate like tiny factories. They receive supplies, generate energy, construct equipment and get rid of waste. Cells also process and store information and communicate with other cells. Keeping everything running requires coordination as well as large amounts of fuel and oxygen.
|Figure 2: Different brain morphology|
Scientists believe Alzheimer's disease prevents parts of a cell's factory from running well. They are not sure where the trouble starts. But just like a real factory, backups, and breakdowns in one system cause problems in other areas. As damage spreads, cells lose their ability to do their jobs and, eventually die, causing irreversible changes in the brain.
Two abnormal structures called plaques and tangles are prime suspects in damaging and killing nerve cells. Plaques are deposits of a protein fragment called beta-amyloid (BAY-tuh AM-uh-loyd) that build up in the spaces between nerve cells. Tangles are twisted fibers of another protein called tau that builds up inside cells. Amyloid plaques are characteristic features of Alzheimer's disease (Figure 3). When amyloid plaques accumulate outside neurons, they lead to a degeneration of the affected neurons.
Quest of solution
Researchers in University laboratories and pharmaceutical companies have been trying hard for a long time to develop the medicine to treat this disease. But, sadly, there's been one glaring absence of breakthroughs in recent decades: a drug to treat Alzheimer’s Disease! The search for a drug to treat dementia has been one of modern medicine's greatest frustrations: a 99.6 percent failure rate.
|Figure 3: Amyloid Plaque|
On July 5, 2018, Biogen (a pharmaceutical company based in Boston, MA, USA) in collaboration with Eisai (a Japan-based company) reported “statistically significant” evidence that the drug, BAN2401, an antibody targeting the beta-amyloid protein, can slow progression of the deadly disease. This was a great news! Eventually, Biogen enjoyed a big jump in its stock price after releasing positive news. July 5 is our wedding anniversary day. We were relaxing and a news popped on my phone and Sijan and me were overwhelmed with this news as our lab was working on this very disease.
The beta amyloid protein has long been hypothesized as the primary cause of Alzheimer’s, and as a result, the target of a majority of drug trials. Removing amyloid oligomers does lessen oxidative stress which may lead to a slower progression of Alzheimer's disease early on. It's the first time a drug has shown the ability to clear the amyloid plaque and more importantly that the clearance of plaque was associated with a slowdown of the cognitive decline.
1. Alzheimer's Association
2. Biogen (www.biogen.com)
3. CNBC News