Alzheimer's disease

Alzheimer's disease (AD) or senile dementia of Alzheimer's type is a disorder of loss of mental functions resulting from brain tissue changes; the causes are yet to be fully elucidated (at least two genes predisposing to AD have been identified). The main characteristic of AD is memory loss. Alzheimer's disease is also manifested in behavorial changes, which may even include sudden periods of defiance, abusive behavior, violence, etc. in people who have no previous history of such behavior (rarely, an affected person experiences euphoria). Thus, Alzheimer's disease presents a problem in patient management, as well. The symptoms of the disease as a distinct nosologic entity were first identified by Emil Kraepelin, and the characteristic neuropathology was first observed by Alois Alzheimer in 1906. In this sense, the disease was co-discovered by Kraepelin and Alzheimer, who worked in Kraepelin's laboratory. Because of the overwhelming importance Kraepelin attached to finding the neuropathological basis of psychiatric disorders, Kraepelin made the generous decision that the disease would bear the name of Alzheimer (J. Psychiat. Res., 1997, Vol 31, No. 6, pp. 635-643).

These changes include loss of brain tissue cells (with a typical upward progression through memory centers such as the entorhinal cortex and the hippocampus) and collection of specific inclusions such as neurofibrillary tangles and senile plaques. It is not yet certain whether these changes are primary (the cause of the disease) or secondary (the result of the disintegration of brain tissue). Alzheimer's disease is the most frequent reason for dementia in the elderly and affects almost half of all patients with dementia. There is no known definitive treatment, although there are drugs which enhance neutrotransmitter transmission which delay the memory loss associated with the disease.

The disease was thought to be uncommon, until the 1960s when it was realized that much of what had been regarded as the normal process of aging was actually the result of this disease. Alzheimer's is considered to be a major public health challenge as a result of the aging population. Typically only 3% of persons aged 65 show signs of the disease while 50% of persons aged 85 have symptoms of Alzheimer's. However the proportion of persons with Alzheimer's begins to decrease after age 85 because of the increased mortality due to the disease, and relatively few people over the age of 100 have the disease.

There are ongoing tests of Alzheimer's disease vaccine. Initial results in animals were promising. However when the first vaccines were used in humans, brain inflammation resulted and the trials were stopped. It is hoped that research will provide a better formulation and that in the future it can be of use in families with history of Alzheimer's Disease.

Unfortunately, a definitive diagnosis of Alzheimer's disease must await an autopsy, at present. However, many increasingly sophisticated diagnostic tests have been proposed (including: brain scans, behavioral tests and testing for genetic predisposition).

Psychological testing generally focuses on memory, attention, abstract thinking, the ability to name objects, and other cognitive functions. However, results of psychological tests do not easily distinguish between Alzheimers Disease and other types of dementia. Psychological testing can be helpful in establishing the presence of and severity of dementia. It can also be useful in distinguishing true dementia from temporary (and more treatable) cognitive impairment due to depression or psychosis, which has sometimes been termed pseudodementia.