Association of residential ambient temperature in childhood with mental disorders from childhood into adulthood: A register-based study

Background

While many environmental exposures in childhood have been associated with later risk of mental disorders, less is known about whether cumulative early-life exposure to ambient temperature could be relevant to later mental health. We combined high-resolution meteorological data with individual-level data from Finnish nationwide registers to investigate associations of childhood ambient temperature exposure with subsequent mental disorders.

Methods

The cohort included 578 067 Finnish individuals born in 1990–1999. For each individual, we calculated average daily exposure to ambient temperature from birth to their 10th birthday based on residential history. The individuals were followed from their 10th birthday until a mental disorder diagnosis, death, emigration, or December 2019. Cox proportional hazards models were used to estimate the associations of childhood temperature exposure with subsequent mental disorders while adjusting for individual-level and area-level confounders.

Findings

Childhood exposure to warmer climatic conditions was monotonically associated with a greater subsequent risk of a mental disorder (compared to the median of the 10-year temperature exposure, HR = 1.10 (95% CI, 1.08–1.12) at the 95th percentile, HR = 0.88 (95% CI, 0.86–0.90) at the 5th percentile). In disorder-specific analyses, the associations were evident for mood and anxiety disorders, and to a lesser extent for sleep and substance use disorders. No consistent evidence was observed with psychotic or eating disorders.

Interpretation

Growing up in warmer climatic conditions was associated with subsequent risk of mental disorders. Further studies in populations residing in different latitudes are needed.