A recent study published in JAMA Psychiatry has provided significant insights into the relationships between sleep, physical activity, and circadian rhythms in individuals with Major Depressive Disorder (MDD). This research utilises accelerometry to assess these domains and their interactions, shedding light on how they collectively influence depression.

Research Objectives and Design

Key Questions

The study aimed to answer the following key questions:

• What is the overlap between accelerometry-assessed sleep, physical activity, and circadian rhythms?
• Can these factors distinguish state and trait in MDD?

Methodology

This cross-sectional study involved 2317 adults from Lausanne, Switzerland, collected during the second wave of a population cohort study. Participants included:

• 1164 adults without MDD
• 185 adults with current MDD
• 968 adults with remitted MDD

Participants wore accelerometers for at least 7 days to gather data on sleep, physical activity, and circadian rhythms. The Joint and Individual Variation Explained (JIVE) method, a multimodal integrative dimension-reduction technique, was used to analyse the data. The statistical analysis was conducted from January 2021 to June 2023.

Main Outcomes and Findings

Demographics

Among the 2317 adults:

• 1261 (54.42%) were female
• Mean age was 61.79 years (SD = 9.97)

Accelerometry Features and Components

The JIVE method reduced 28 accelerometry features to 3 joint components and 6 individual components:

• Joint Components: Explained significant portions of the total variation in sleep (58.5%), physical activity (79.5%), and circadian rhythm domains (54.5%).
• Individual Components: Included 1 sleep component, 2 physical activity components, and 3 circadian rhythm components.

Associations with MDD

Both current and remitted MDD were associated with the first 2 joint components:

• First Joint Component: Distinguished by high-intensity physical activity and the amplitude of circadian rhythm.
• Second Joint Component: Related to the timing of both sleep and physical activity.

Key findings include:

• Individuals with MDD exhibited reduced and more fragmented physical activity.
• MDD was characterised by lower amplitude of circadian rhythm.
• There was later timing of both sleep and the peak of physical activity in individuals with MDD.
• Dampened circadian rhythmicity may serve as a trait marker for MDD.

Implications for Future Research

The study highlights several important points for future research:

• The value of accelerometry as a potential biomarker for subtypes of depression.
• The importance of considering the full 24-hour sleep-wake cycle in studies related to mood disorders.
• Joint influences of physical activity, circadian rhythms, and the timing of sleep and physical activity are crucial in understanding MDD.

Source: JAMA Psychiatry