Seasonal trends in antidepressant prescribing, depression, anxiety, and self-harm in adolescents and young adults: an open cohort study using UK primary care data

Problem

Weather and seasons, or stressful periods associated with their education could affect young people’s mental health. Members of a Young Person’s Advisory Group asked us to investigate whether there are particular periods in the year when adolescents have more mental health issues. We aimed to examine whether there are different seasonal trends in primary care antidepressant prescribing, depression, anxiety, and self-harm in adolescents compared with young adults in England.

Approach

We used information about antidepressant prescribing and mental health events between 2006 and 2019 from the QResearch database, which contains anonymised primary care electronic health records. We studied males and females in three age groups: 14-18 years (adolescents), 19-23 years and 24-28 years. We calculated monthly incidence rates and incidence rate ratios of prescriptions for the most commonly prescribed antidepressants (selective serotonin reuptake inhibitors) and records of depression, anxiety and self-harm. Incidence rate ratios were adjusted for year, region, deprivation, ethnic group and number of working days in a month.

Findings

The study included 5,081,263 people over 17.9 million person-years. Antidepressant prescribing, depression and anxiety incidence rates were higher in autumn months for male and female adolescents, but not for the older age groups. For female adolescents, the highest incidence rate ratios compared with January were in November for SSRI prescribing (1.75, 95% confidence interval: 1.67-1.83, p<0.001), depression (1.29, 1.25-1.33, p<0.001) and anxiety (1.17, 1.13-1.22, p<0.001). For male adolescents, the highest incidence rate ratios were also in November for SSRI prescribing (1.72, 1.61-1.84, p<0.001) and depression (1.29, 1.23-1.35, p<0.001), and in September for anxiety (1.19, 1.12-1.27, p<0.001). Self-harm was lowest in August for adolescents, lower in July-December for 19-23-year-old females and stable throughout the year for other groups.

Consequences

There were higher rates of antidepressant prescribing, depression and anxiety at the start of the school year in adolescents. Support around mental health issues from GPs and schools should be focussed during this period. Future studies should examine whether these results apply to younger children and develop interventions to lessen their impacts on adolescents.