Associations between circadian activity rhythms and functional brain abnormalities among euthymic bipolar patients: a...

Area of Science:

• Neuroscience
• Psychiatry
• Sleep Medicine

Background:

• Euthymic bipolar disorder (BD) patients exhibit working memory deficits and brain abnormalities, with significant heterogeneity.
• Sleep and circadian rhythm disturbances are considered core features of BD, potentially explaining functional heterogeneity.

Purpose of the Study:

• To investigate the association between sleep/circadian rhythm abnormalities and functional brain responses during a working memory task in BD patients.
• To explore how sleep and circadian patterns relate to brain activity variations in individuals with BD.

Main Methods:

• 14 euthymic BD patients underwent 7-day actigraphy and functional magnetic resonance imaging (fMRI) during a working memory task.
• Sleep/circadian variables were compared between BD patients and two healthy comparison (HC) groups.
• Associations between significant sleep/circadian variables and fMRI brain response were analyzed.

Main Results:

• BD patients displayed significantly abnormal sleep efficiency, rhythm robustness, mesor, and amplitude-to-width ratio.
• Variability in these sleep/circadian measures correlated with abnormal brain responses in the dorsolateral prefrontal cortex and supramarginal gyri.

Conclusions:

• Abnormal activity rhythms and sleep efficiency in BD patients are linked to altered working memory brain responses.
• These preliminary results suggest the sleep/circadian system is crucial for understanding functional brain deficits in BD.