Comorbidity within mental disorders: a comprehensive analysis based on 145 990 survey respondents from 27 countries

Area of Science:

• Psychiatry and Epidemiology
• Mental Health Research
• Public Health

Background:

• Epidemiological data suggests a link between the presence of one mental disorder and an increased likelihood of developing others.
• Understanding the patterns and risks of mental disorder comorbidity is crucial for effective public health interventions.

Purpose of the Study:

• To conduct a comprehensive analysis of lifetime pair-wise comorbidity among common mental disorders.
• To investigate the temporal associations and risks of developing secondary mental disorders following an initial diagnosis.

Main Methods:

• Utilized data from the WHO World Mental Health (WMH) surveys, encompassing 145,990 adult respondents across 27 countries.
• Analyzed 548 temporally-ordered disorder pairs based on retrospectively reported age-of-onset for 24 DSM-IV mental disorders.
• Employed Cox proportional hazards models to calculate hazard ratios (HRs) and product-limit methods for absolute risk estimation.

Main Results:

• A significant association was found between every prior lifetime mental disorder and an increased risk of subsequent first onset of other disorders.
• The median hazard ratio (HR) for developing a secondary disorder was 12.1, with risks most pronounced between closely related disorders and within the first 1-2 years.
• Elevated comorbidity risk persisted for at least 15 years, with appreciable absolute risks of secondary disorders observed over time.

Conclusions:

• This large-scale, multi-country study confirms the high prevalence of mental disorder comorbidity.
• Findings underscore the importance of understanding temporal risks for developing effective primary prevention programs targeting secondary mental disorders.