Although often confused, dementia and schizophrenia are two distinct illnesses, with different causes and symptoms. Schizophrenia usually emerges during adolescence or young adulthood, while dementia often begins in old age. Both conditions may be associated with cognitive deficits (impairments in thinking, memory, and other brain functions), but such problems in schizophrenia are typically less severe.
Some of the confusion may have originated with a term used by a 19th century scientist. According to E. Fuller Torrey, M.D., in “Surviving Schizophrenia,” Emil Kraepelin assigned the name “dementia praecox” to the syndrome now called “schizophrenia.” The term means “dementia of early life.”
Schizophrenia is a severe, chronic psychiatric disorder marked by “positive” and “negative” symptoms. Positive symptoms, such as hallucinations and delusions, are distortions of reality that should not be present, but are. Negative symptoms, including apathy and social withdrawal, represent characteristics that should be present, but are not.
Dementia is characterized by multiple cognitive problems that arise as a direct physiological result of an illness or substance. According to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), the incidence of dementia from Alzheimer’s disease increases with age, especially after age 75. Twenty percent of people 85 years old and over have dementia from Alzheimer’s. However, the National Institute on Aging notes that some decline in memory can be a normal part of the aging process; this expected decline is not dementia.
Non-Alzheimer’s dementia can arise from a variety of diseases and conditions, including head trauma, Parkinson’s disease, and Huntington’s disease. It can also be induced by use or abuse of substances. Schizophrenia is not caused by a specific medical condition or substance.
Neuroleptics (antipsychotic medications) are used in both schizophrenia and dementia. For people with schizophrenia, the medications can help ease paranoia, voices, and other symptoms. For those with dementia, antipsychotics might be used to calm aggression or delirium.