Alzheimer’s disease
a progressive neurodegenerative disease characterized by cortical atrophy, neuronal death, synapse loss, and accumulation of amyloid plaques and neurofibrillary tangles, causing dementia and a significant decline in functioning. Early features include deficits in memory (e.g., rapid forgetting of new information, impaired recall and recognition), anomia, executive dysfunction, depressive symptoms, and subtle personality changes such as decreased energy, social withdrawal, indifference, and impulsivity. As the disease progresses, there is global deterioration of cognitive capacities with intellectual decline, aphasia, agnosia, and apraxia as well as behavioral features, including apathy, emotional blunting, mood-dependent delusions, decreased sleep and appetite, and increased motor activity (e.g., restlessness, wandering). Major risk factors for Alzheimer’s disease include advanced age (it typically
occurs after age 70), a family history of the disease, and genetic factors, particularly the presence of the ApoE4 allele (see apolipoprotein E) on chromosome 19. In a small minority (＜10%) of cases, referred to as having early-onset Alzheimer’s disease, a diagnosis is made between the ages of 30 and 65 and is usually attributed to genetic causes. [first described in 1907 by Alois Alzheimer (1864–1915), German neurologist]