Objective: To examine the 1-year prevalence of psychotic symptoms and schizophrenia in nondemented 95-year-olds, and to examine the relation between psychotic symptoms and other psychiatric symptoms, sensory impairments, and cognitive functioning.
Participants: The representative sample was 95-year-olds living in Göteborg, Sweden (N = 338). Individuals with dementia were excluded (N = 175), leaving 163 subjects for this study.
Design: This was a cross-sectional population study, including psychiatric and physical examinations, cognitive tests, and interviews with close informants.
Measurements: Diagnosis of schizophrenia, psychotic symptoms, paranoid ideation and dementia according to Diagnostic and Statistical Manual of Mental Disorders, Third Revision (DSM-III) were measured. Cognitive function was tested with the Mini-Mental State Exam. Other psychiatric symptoms were measured by the Comprehensive Psychopathological Rating Scale.
Results: The one-year prevalence of any psychotic symptom was 7.4% (95% confidence interval [CI] 3.8-12.5); including hallucinations 6.7% (95% CI 3.4-11.8) and delusions 0.6% (95% CI 0.0-3.4). Four (2.4%) individuals fulfilled DSM-III-R criteria for schizophrenia. Individuals with psychotic symptoms or paranoid ideation did not differ regarding cognitive functioning compared with individuals without these symptoms. Individuals with hallucinations and paranoid ideation had an increased frequency of previous paranoid personality traits compared with individuals without psychotic symptoms and paranoid ideation. No individuals with psychotic symptoms had a formal thought disorder, incoherence of speech, or flat affect.
Conclusion: The authors found a high prevalence of psychotic symptoms, paranoid ideation, and schizophrenia in the very old. Most of the symptoms were elucidated by information from key informants, illustrating the importance of including relatives in the evaluation of elderly persons.