Alzheimer’s disease is a progressive condition in which nerve cells in the brain degenerate and the brain shrinks. Alzheimer’s disease is the most common cause of dementia (a general decline in all areas of mental ability). Its onset is uncommon before the age of 60, but incidence increases steadily with age thereafter.
Early onset Alzheimer’s disease, in which symptoms develop before the age of 60, is often inherited as a dominant trait. Late onset Alzheimer’s disease is associated with one of the genes that is responsible for the production of the blood protein apolipoprotein E. Genetic factors also result in the abnormal deposition of a protein in the brain called beta amyloid. Other chemical abnormalities include deficiency of the neurotransmitter acetylcholine.
Symptoms and signs
The features of Alzheimer’s disease vary, but there are three broad stages. At first, the affected individual becomes increasingly forgetful; and problems with memory may cause anxiety and depression. Some deterioration in memory is a feature of normal aging, and this alone is not evidence of dementia.
In the second stage of the disease, loss of memory, particularly for recent events, gradually becomes more severe, and there may be disorientation as to time or place. The person’s concentration and numerical ability decline, and there is noticeable dysphasia (inability to find the right word). Anxiety increases, mood changes are unpredictable, and personality changes may occur. If the patient is left unsupervised, he or she may repeatedly wander off.
Finally, confusion becomes profound. There may be symptoms of psychosis, such as hallucinations and delusions. Signs of nervous system disease, such as abnormal reflexes (involuntary actions) and faecal or urinary incontinence, begin to develop.
Alzheimer’s disease is usually diagnosed from the symptoms, but tests including blood tests and CT scanning or MRI (techniques that produce cross-sectional or three-dimensional images) of the brain may be needed to exclude other causes of dementia.
The most important aspect of treatment for Alzheimer’s disease is the provision of suitable nursing and social care for sufferers and support for their relatives. Tranquillizer drugs can often improve difficult behaviour and to help with sleep. Treatment with acetylcholinesterase inhibitors, such as rivastigmine and donepezil, may slow the progress of the disease for a time, but will not improve mental ability. Side effects such as nausea and dizziness may occur.