Even schizophrenics fear Alzheimer's disease

Abstract

The term dementia dates back to 50 BC, when Lucretius used it to mean “being out of one's mind.” Over time, dementia has become synonymous with Alzheimer's disease (AD), characterized by impaired memory. In the late nineteenth century, Emil Kraepelin's description of dementia praecox—later reclassified as schizophrenia—often included end-stage confusion and memory loss, suggesting a clinical overlap with what is now recognized as AD. Kraepelin's contemporary, Alois Alzheimer, described “presenile dementia” in Auguste Deter, whose history of paranoia and progressive cognitive decline may represent a schizophrenia-to-AD trajectory. The author reports a rare single modern case of a woman with lifelong untreated schizophrenia who developed AD-like dementia in her late 50 s, supporting the speculative hypothesis that AD was once a frequent terminal stage in the natural history of schizophrenia prior to the advent of antipsychotic therapy in the 1950s. Epidemiologic data show substantially elevated dementia prevalence in elderly schizophrenics. Emerging evidence links schizophrenia and AD through shared neurobiological mechanisms, including neuroinflammation and structural brain changes. The author proposes and speculates that long-term antipsychotic use may prevent AD progression via enhanced adult neurogenesis, as dopamine blockade alleviates the neurogenesis-suppressing effects of hyperdopaminergia. This hypothesis, that neurogenesis stimulated by chronic antipsychotic therapy mitigates neurodegeneration, offers a unifying model for the decline in dementia incidence among treated schizophrenics and reframes adherence motivation: treating schizophrenia may not only control psychosis but also protect against AD, a condition even schizophrenic patients fear.