To better understand the developmental course of personality disorders and the scope of diagnosis and treatment in specialist health care, we estimate incidence rates of specialist health care personality disorder diagnosis by age, gender, and calendar time, as well as lifetime risks, in the whole population of Norway. The measures provided are foundational for developmental theories of personality disorders, for treatment planning, and for later epidemiological studies. We studied every person born 1940 or later and resident and at risk in Norway between January 1st, 2010 and December 31st, 2022 (n = 6,040,689). We used Poisson regression with penalized cubic splines to model incidences of personality disorder diagnosis across age, gender, and calendar time, and calculated lifetime risks while accounting for competing risks of death and emigration. Across specific disorders, incidence was highest in young adulthood. The lifetime risk of any personality disorder diagnosis in specialist health care was 5.4%. The two most incident specific diagnoses were borderline and avoidant personality disorders. Generally, incidence increased through the study period, with an incidence rate ratio (IRR) of 1.21 between 2022 and 2010 – this trend was largely due to borderline (IRR = 1.40) and avoidant (IRR = 1.66) personality disorder becoming more common. Lifetime risk of any personality disorder diagnosis was higher among women (cumulative incidence = 6.7%) than among men (cumulative incidence = 4.1%), and increased more through the study period among women (IRR = 1.34) than among men (IRR = 1.03). Personality disorders are common in the Norwegian population, often first identified in specialist health care during early adulthood.
Valstad et al. (Tue,) studied this question.