ALZHEIMER'S DISEASE: AN INCREASING DEBILITATING CONDITION

Alzheimer's disease (AD) accounts for 60% to 70% of cases of dementia. It was first described by German psychiatrist and pathologist Alois Alzheimer in 1906.

- Dr Arun Oommen

It is a chronic neurodegenerative disease that usually starts slowly and gets worse over time. The most common early symptom is difficulty in remembering recent events (short-term memory loss). As the disease advances, symptoms can include problems with language, disorientation (including easily getting lost), mood swings, loss of motivation, not managing selfcare, and behavioural issues. As a person's condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the average life expectancy following diagnosis is three to nine years.

In 2010, there were between 21 and 35 million people worldwide with AD. It most often begins in people over 65 years of age, although 4% to 5% of cases are early-onset Alzheimer's which begin before this. In India the number of people with AD and other dementias is increasing every year because of the steady growth in the older population resulting in an estimated increase of twofold by 2030 and threefold by 2050 in developed countries.

Causes

The cause of Alzheimer's disease is poorly understood. Alzheimer's disease results from a combination of genetic, lifestyle and environmental factors that affect the brain over time. About 70% of the risk is believed to be genetic with many genes usually involved. The genetic heritability of Alzheimer's disease based on reviews of twin and family studies, ranges from 49% to 79%. Most cases of Alzheimer's disease do not exhibit autosomal-dominant inheritance and are termed sporadic AD. Around 0.1% of the cases are familial forms of autosomal (not sex-linked) dominant inheritance, which have an onset before the age of 65. This form of the disease is known as early onset familial Alzheimer's disease.