SNP Shot: Genomic Insights

Alzheimer's disease is a progressive brain disorder that leads to dementia, characterized by a gradual decline in memory, judgment, and overall cognitive function. It typically affects individuals over 65, although less frequent forms can emerge earlier in adulthood.

The primary symptom of Alzheimer's disease is memory impairment. Initially, this may manifest as mild forgetfulness, but it progressively worsens, ultimately impacting most aspects of daily life. Individuals with Alzheimer's may experience disorientation even in familiar environments and struggle with everyday tasks such as cooking, laundry, and other household duties. Recognizing people and naming objects may also become challenging. As the disease progresses, individuals often require increasing assistance with basic self-care activities like dressing, eating, and hygiene.

As Alzheimer's advances, personality and behavior changes may occur, making social interaction difficult. Other common symptoms include agitation, restlessness, social withdrawal, and a decline in language abilities. In the advanced stages, individuals with Alzheimer's disease typically require complete care.

The typical survival time for individuals with Alzheimer's disease after symptom onset is 8 to 10 years, although the disease course can vary from 1 to 25 years. Survival is generally shorter for those diagnosed after the age of 80 compared to those diagnosed at a younger age. Death in Alzheimer's disease commonly results from complications such as pneumonia, malnutrition, or general physical decline (inanition).

Alzheimer's disease can be categorized as either early-onset or late-onset. Early-onset Alzheimer's manifests between a person's thirties and mid-sixties, while the late-onset form appears during or after their mid-sixties. Early-onset Alzheimer's is considerably less common than the late-onset form, accounting for less than 10 percent of all cases.

Inheritance:

Early-onset familial Alzheimer's disease follows an autosomal dominant inheritance pattern. This means that having just one copy of a mutated gene in each cell is enough to cause the disorder. In most instances, an affected individual inherits the altered gene from a parent who also has the condition. The inheritance pattern for late-onset Alzheimer's disease is complex and not fully understood. Individuals who inherit one copy of the APOE ε4 allele have a heightened risk of developing the disease, and the risk increases further with two copies. It is crucial to remember that the APOE ε4 allele only increases the risk of developing Alzheimer's; it does not guarantee the disease. Not everyone with Alzheimer's has the ε4 allele, and not everyone with the ε4 allele will develop Alzheimer's.