Complaints of declining memory are common with advancing age. Memory disorders are associated with difficulty in learning and retaining new information. Dementia is defined as an insidious decline in a number of mental functions resulting in the loss of personal and social independence in a previously competent individual. Even though the most common component of dementia is memory loss, isolated defects in memory or in language do not qualify as dementia, which is usually associated with defective reasoning, decision making and judgment.
Dementia occurs when several of the cerebral systems that support learning, memory, language, emotion and reason are dysfunctional. Dementia can be self-limited (e.g., damage from head trauma or cardiac arrest) or progressive (e.g., dementia associated with Alzheimer's Disease).
Epidemiological studies indicate that approximately 15% of patients greater than 65 years old suffer from some form of dementia, while the incidence increases to 23% in patients 75 to 84 years old and 48% in patients greater than 85 years old. Objective assessment of memory loss and cognitive impairment is done by using neuropsychological testing