The Incidence of Schizophrenia Across the Lifespan: A Longitudinal Register Study in an Urban Population.

Abstract

Objectives: The idea that schizophrenia manifests before age 40 has shaped research and clinical practice. We aimed to estimate the incidence rate (IR) and lifetime morbidity risk (LMR) and age of onset of schizophrenia over a much wider age range.

Methods: Age- and sex-stratified incidence rates and lifetime morbidity risk for schizophrenia over ages 20-79 years in the city of The Hague in The Netherlands during a 15-year study period were estimated. A register covering all psychiatric services with clinical diagnoses was used, with a cumulative time frame.

Results: The pooled incidence of schizophrenia was 47 (95% confidence interval (CI) 45-49) per 100.000 person-years over the age range 20-79 years. The incidence decreased from 67 (95% CI: 63-71) in the early onset age range between 20-39 years, 45 (95% CI: 42-49) in the late onset age range between 40-59 years, and 19 (95% CI: 16-22) in the very-late onset age range of over 60 years. The lifetime morbidity risk (LMR) up to age 79 was 3.7% for males and 2.3% for females. At least 5 out of 6 (84%) of schizophrenia cases were diagnosed after the age of 30 years, and nearly half (46%) after the age of 40 years.

Conclusions: Despite higher incidence rates in the youngest cases, particularly for males, onset after age 30 years of age is the norm, not the exception. Case finding should extend across the lifespan.