Alzheimer's Disease and Other Dementias
Alzheimer's disease is the most common form of dementia. It produces a gradual but continuous decline in memory and intellectual abilities. Victims have trouble performing once familiar tasks, learning new things, paying attention, and generally understanding events.
Alzheimer's disease is linked to the appearance of dense, plaque-like material in the brain, tangles of cellular proteins, and the death of neurons in parts of the cerebral cortex responsible for higher mental functions.
Although patients with this form of dementia may show psychotic symptoms, Alzheimer's disease is distinguished from schizophrenia by loss of memory and other basic brain functions. These losses follow a very evident decline in short-term memory over a span of several months. Furthermore, it is a disease that occurs after the age of sixty-five in the vast majority of patients.
Besides memory loss and confusion, people with Alzheimer's disease may also develop paranoia, other delusions, or hallucinations and behavioral changes. When these changes result in disorganized behavior, they appear similar to some of the behaviors that are seen in schizophrenia.
Dementia can also be caused by hardening of the arteries in the brain (cerebral arteriosclerosis) and repeated mini-strokes, both of which deprive key brain regions of their essential blood supply. In some patients, this damage can produce psychotic-like symptoms.
It is not unusual for patients who suffer from Huntington disease, an inherited, neurological condition characterized by involuntary muscle movements, to be mistakenly diagnosed first with schizophrenia. The mental deterioration and psychotic behavior that can accompany Huntington disease is responsible for the confusion.