ADHD and depression: investigating a causal explanation

Summary & key facts

The paper used two different approaches to test whether ADHD raises the risk of later depression. In a UK birth cohort of 8,310 people, childhood ADHD at about age 7 was linked to higher risk of recurrent depression between ages 18 and 25 (OR 1.35, 95% CI 1.05–1.73). Genetic analyses (Mendelian randomization) suggested that genetic liability for ADHD increases risk of major depression (OR 1.21, 95% CI 1.12–1.31) and has a smaller effect on a broader depression measure (OR 1.07, 95% CI 1.02–1.13). The authors say these results are consistent with a possible causal effect for some definitions of depression, but results vary by how depression is defined and are not definitive.

Key facts:

• In the ALSPAC cohort (N = 8,310) childhood ADHD measured at about age 7 was associated with recurrent young-adult depression (odds ratio 1.35, 95% CI 1.05–1.73).
• Childhood ADHD in the cohort was measured with the parent-rated SDQ ADHD subscale and coded as ‘ADHD’ using the recommended cut-point (>7).
• Recurrent depression in young adulthood was defined as scoring >11 on the self-rated Short Mood and Feelings Questionnaire (sMFQ) at least twice between ages 18 and 25.
• Mendelian randomization (MR) analyses using published GWAS data found that genetic liability for ADHD was associated with major depression (OR 1.21, 95% CI 1.12–1.31).
• MR analyses using a broader definition of depression showed a smaller association (OR 1.07, 95% CI 1.02–1.13), indicating results depend on how depression is defined.
• The authors note that shared genetic factors, overlapping symptoms (for example concentration problems), or other confounding could also explain associations, and that MR depends on specific assumptions and is not conclusive on its own.

Abstract

Our findings suggest that ADHD increases the risk of depression later in life and are consistent with a causal effect of ADHD genetic liability on subsequent major depression. However, findings were different for more broadly defined depression.

Topics

Attention Deficit Hyperactivity Disorder Functional Brain Connectivity Studies Health, Environment, Cognitive Aging

Categories

Health Sciences Medicine Psychiatry and Mental health

Tags

Causal model Causality (physics) Clinical psychology Cognition Cognitive psychology Depression (economics) Developmental psychology Liability MEDLINE Psychiatry Psychology

Conditions & symptoms

ADHD Depression Difficulty focusing Sadness or low mood