Causal links between sedentary behavior, physical activity, and psychiatric disorders: a Mendelian randomization...

Area of Science:

• Genetics
• Psychiatry
• Epidemiology

Background:

• Sedentary behavior and physical inactivity are linked to increased psychiatric disorder risk.
• The exact causal relationship between these behaviors and psychiatric disorders remains unclear.

Purpose of the Study:

• To investigate the potential causal links between sedentary behavior, physical activity, and susceptibility to depression, schizophrenia, and bipolar disorder.
• Utilized a two-sample Mendelian randomization (MR) approach for robust analysis.

Main Methods:

• Identified genetic instruments for sedentary behaviors and physical activity from UK Biobank GWAS data (n=422,218).
• Employed inverse variance weighting (IVW) for primary analysis.
• Conducted sensitivity analyses including Cochran's Q test, MR-Egger intercept, and leave-one-out analysis to ensure result validity.

Main Results:

• Genetically predicted leisure TV watching showed a significant association with increased depression risk (OR=1.027).
• Higher accelerometer-assessed fraction accelerations (>425 milligravities) were linked to decreased depression risk (OR=0.951).
• Leisure TV viewing demonstrated a protective effect against bipolar disorder (OR=0.719), and driving showed a slight protective effect against schizophrenia (OR=0.092).

Conclusions:

• Compelling evidence supports a link between excessive TV watching and depression and bipolar disorder.
• Higher physical activity levels, particularly vigorous exercise, may offer a genetic protective factor against depression.
• Reducing sedentary activities like TV watching and increasing vigorous physical activity are recommended to mitigate psychiatric disorder risk.