Seasonal variation in specific depressive symptoms: A population based study

Area of Science:

• Mental Health Research
• Epidemiology
• Psychiatry

Background:

• Depression symptoms can fluctuate with seasons, particularly in younger populations.
• Understanding specific symptom variations is crucial for accurate diagnosis and treatment.
• Previous research suggests seasonal patterns in mood disorders, but symptom-specific data in youth is limited.

Purpose of the Study:

• To investigate which specific symptoms of depression exhibit seasonal variation in Canadian youth and adults.
• To compare the seasonal symptom profiles between adolescent and adult populations.
• To identify potential differences in seasonal affective disorder (SAD) symptom presentation across age groups.

Main Methods:

• Cross-sectional analysis of the 2015/2016 Canadian Community Health Survey data (n≈53,000).
• Utilized the Patient Health Questionnaire-9 (PHQ-9) to assess depressive symptoms throughout the year.
• Employed logistic regression with quadratic terms to identify seasonal effects, stratified by age (youth 12-24, adults 25+).

Main Results:

• In youth, 8 PHQ-9 symptoms varied seasonally, including anhedonia, depressed mood, sleep disturbances, fatigue, appetite changes, guilt, psychomotor changes, and concentration difficulties.
• Adults showed seasonal variation only in sleep and appetite symptoms.
• Crucially, symptoms related to self-harm or suicidal ideation did not exhibit seasonality in either age group.

Conclusions:

• A broad range of depressive symptoms demonstrate seasonal patterns in Canadian youth.
• In contrast, seasonal influences on depression in adults appear more restricted to sleep and appetite.
• These findings highlight age-specific differences in the manifestation of seasonal depression symptoms.