When Do Mental Disorders Typically Begin? A Global Look at Age of Onset

What you need to know

• Mental disorders often first appear during childhood, adolescence and young adulthood, with over 60% beginning before age 25
• Different types of disorders tend to emerge at different ages, from early childhood for conditions like ADHD to early adulthood for psychotic disorders
• Understanding these typical onset patterns can help guide mental health prevention efforts and early intervention programs
• The current separation between child/adolescent and adult mental health services at age 18 does not align with the actual onset patterns of most disorders

The importance of early intervention for mental health

Mental health conditions can have a major impact on people’s lives, reducing life expectancy by 10-15 years on average compared to the general population. However, early intervention when mental health problems first emerge can significantly improve outcomes. Prevention and early treatment have the potential to alter the course of a disorder and lead to better long-term results.

To provide the most effective early intervention and prevention, it’s crucial to understand when different mental health conditions typically first appear. While some previous research has looked at this, the findings have often been inconsistent or limited to specific disorders or populations.

This new study aimed to provide a comprehensive, global picture of the typical age of onset for a wide range of mental disorders. The researchers conducted a large meta-analysis, combining data from 192 high-quality epidemiological studies from around the world. This allowed them to estimate onset patterns across different types of mental health conditions.

Key findings on mental disorder onset

The meta-analysis revealed several important patterns in when mental disorders tend to first emerge:

• Overall, any mental disorder had emerged by age 14 in 34.6% of people, by age 18 in 48.4%, and by age 25 in 62.5%.

• The peak age for onset of any mental disorder was 14.5 years old.

• Different categories of disorders showed distinct onset patterns:

  • Neurodevelopmental disorders (like ADHD and autism) had the earliest onset, with 61.5% emerging by age 14.

  • Anxiety disorders also tended to appear early, with 38.1% onset by age 14.

  • Eating disorders often emerged in adolescence, with 48.1% onset by age 18.

  • Psychotic disorders and personality disorders typically appeared later, with only about 12% onset by age 18 but close to 50% by age 25.

  • Mood disorders like depression had the latest typical onset, with only 34.5% emerging by age 25.

• For specific conditions, the median age of onset ranged from 8-13 years old for phobias, separation anxiety, autism and ADHD, to 30-35 years old for post-traumatic stress disorder, depression, generalized anxiety disorder, bipolar disorder and acute psychotic disorders.

• There were no major differences in onset patterns between males and females for most disorders. Some substance use disorders and mood disorders showed a trend toward slightly earlier onset in males.

Implications for mental health care

These findings have important implications for how mental health services are structured and delivered:

Rethinking the child/adult divide

Currently, in many countries, mental health services are divided between child/adolescent services and adult services, with the split typically occurring at age 18. However, this artificial divide does not align well with the actual onset patterns of most mental disorders.

The peak age of onset for mental disorders overall was 14.5 years, with nearly half of all conditions emerging by age 18. Many disorders that are often considered “adult” conditions, like psychosis and personality disorders, frequently begin in the late teens and early 20s. This suggests a need for mental health services that can provide continuous care across the transition from adolescence to adulthood.

Targeting prevention and early intervention

Understanding the typical onset ages for different disorders can help guide when and how to target prevention and early intervention efforts:

• For neurodevelopmental and anxiety disorders, preventive approaches may need to start in early childhood, potentially involving parents, preschools and primary schools.

• Eating disorder prevention could focus on the pre-teen and early teen years.

• For psychotic disorders, personality disorders, and mood disorders, high schools and colleges may be key settings for prevention and early detection programs.

• General health services for young people, like pediatricians and school health services, could play an important role in early detection across multiple disorder types.

Promoting good mental health

Beyond just preventing and treating disorders, there’s also a need to promote positive mental health and wellbeing starting from an early age. Programs to build resilience, emotional skills, and healthy coping mechanisms could be valuable throughout childhood and adolescence.

Conclusions

• Mental disorders often emerge early in life, with over 60% beginning before age 25. This highlights the need for mental health services and support aimed at children, adolescents and young adults.

• Different types of disorders tend to appear at different ages. Prevention and early intervention efforts should be timed and targeted accordingly.

• The current separation between child/adolescent and adult mental health services at age 18 does not match the actual onset patterns of most disorders. More integrated services spanning adolescence and young adulthood may be beneficial.

• Schools, colleges, pediatricians, and general health services could play key roles in mental health promotion, prevention, and early detection for young people.

This comprehensive look at the global patterns of mental disorder onset provides valuable guidance for improving mental health care systems. By aligning services and interventions with the actual timing of when problems tend to emerge, we may be able to prevent or mitigate many mental health conditions before they become severe and chronic.