DEMENTIA

Dementia, commonly referred to in everyday language as “senility” or “memory loss,” can be briefly defined as the loss of intellectual functions to a degree that interferes with daily living activities. The term dementia originates from Greek, derived from de-mense, meaning “loss of the mind.” It is used to describe the gradual deterioration and loss of mental and cognitive functions over time. Dementia is not the name of a single disease; rather, it is a general term encompassing all conditions characterized by impairment of memory and other cognitive abilities.

Excluding cognitive decline disorders seen in childhood, dementia in adults generally emerges in older age groups. Because of this characteristic, for many years cognitive slowing and intellectual decline observed in elderly individuals were attributed to the physiological aging process of the brain (senility). However, clinical observations and supporting studies have demonstrated that dementia is distinct from normal physiological aging. Indeed, the presence of individuals in their eighties or nineties who retain normal cognitive functions clearly supports the view that aging alone is not the cause of dementia.

In reality, dementia is a clinical syndrome that arises as a result of different pathological processes. In this respect, similar to epilepsy, the term dementia merely describes a clinical presentation. Nevertheless, there are significant differences in the frequency of dementias caused by various etiological factors. With the extension of human life expectancy, there has been a marked increase in the proportion of the elderly population, accompanied by a parallel rise in the number of patients with dementia. This situation has accelerated research on dementia, and neuropathological studies have revealed an important reality.

Histopathological examination of the brains of individuals over the age of sixty-five, both with and without dementia, has shown that approximately 50% of patients with dementia exhibit findings characteristic of Alzheimer’s disease, which was first defined as a distinct clinical and pathological entity in 1907. In about 15% of cases, dementia has been found to be due to vascular disorders; this condition is referred to as vascular dementia. In 14% to 25% of autopsy cases, features of both Alzheimer’s disease and vascular pathology coexist, a condition known as mixed dementia.

As these figures indicate, Alzheimer’s disease accounts for nearly half of the causes of dementia in the elderly population. When dementias associated with other neurodegenerative diseases (such as Lewy body dementia and Parkinson’s disease) are included, this rate rises to nearly 99%. Dementias related to toxic, metabolic, and endocrine causes, as well as those associated with brain tumors and other neurological diseases, constitute only a very small proportion.

An increasing prevalence is observed in Alzheimer’s disease and many other disorders affecting the brain. With the identification of their causes, elimination of risk factors, and the development of new treatment options, the process of aging will become more favorable and healthier.