About Alzheimer’s disease

Alzheimer’s disease is a progressive brain disorder characterized by the gradual decline of cognitive functions, particularly memory and reasoning abilities, eventually interfering with a person’s ability to live independently. It is the most common cause of dementia, typically appearing in people over 60, though rare cases of early-onset Alzheimer’s can occur. First identified in 1906, the disease begins by impairing memory and gradually affects language, reasoning, and social behavior. Age is the greatest risk factor, but lifestyle factors such as education level, cognitive activity, and head trauma also contribute. While it has a significant impact, 99% of cases are not inherited..

The biology behind Alzheimer’s disease

The biological changes caused by Alzheimer’s are profound and disruptive. Clumps of amyloid plaques and tangled fibers accumulate in the brain, leading to inflammation and an inability to clear waste and toxins. Microglia cells, which usually handle this maintenance, struggle to manage the buildup, resulting in the gradual loss of neural connections. This disruption starts in the hippocampus and entorhinal cortex- key areas for memory- before spreading to other regions like the cerebral cortex. As neurons die, communication between the brain, muscles, and organs deteriorates. Reduced blood flow compounds the damage, depriving the brain of oxygen and causing it to shrink over time. These changes highlight the intricate systems at play and the devastating effects when they fail.

Epidemiology of Alzheimer’s disease

Alzheimer’s disease affects more than six million Americans aged 65 and older, and its prevalence is increasing. Late-onset Alzheimer’s typically begins after age 60, and life expectancy varies—3 to 4 years for older patients, and up to 10 years for those diagnosed younger. The disease places a heavy burden on caregivers and family members, adding an emotional and social dimension to its impact. While the majority of Alzheimer’s patients are White, African Americans and Hispanics are statistically more likely to develop the disease. About 11% of people over 65 are affected.

Treatment options for Alzheimer’s disease

Although there is no cure for Alzheimer’s, treatments are available to help manage symptoms and slow progression. Medications like memantine and donepezil regulate brain chemicals and are most effective in the early to mid-stages of the disease. Additional treatments, such as antipsychotics, anti-anxiety drugs, and sleep aids, address specific symptoms but don’t target the root cause. Side effects can be a challenge, and the complexity of Alzheimer’s makes a single cure unlikely. Research is ongoing, with a focus on improving quality of life and finding more effective ways to manage the disease.

The human genes related to Alzheimer’s disease and their orthologous genes in model organisms

We collected Alzheimer associated genes from various public resources such as OMIM, GWAS and ClinVar, and built a database for users to mine the list with ease. There are 2700 protein-coding genes in total collected and we assigned the confidence based on number of resource as well as the publication counts if the gene is studies in two or more publications of Alzheimer focus. 388 (14%) are assigned high rank while 870 (32%) are assigned moderate rank. Studying the function of Alzheimer genes in animal models have proven to be important to advance our understanding about the molecular mechanism of Alzheimer disease. To facilitate such studies, we also mapped the human genes to the major model organisms using DIOPT.