CLOCK gene variants associated with the discrepancy between subjective and objective severity in bipolar depression

Area of Science:

• Psychiatry
• Genetics
• Chronobiology

Background:

• Discrepancy between subjective and objective depression severity predicts treatment outcomes and suicidal risk.
• Evening-type depressed patients exhibit higher depressive cognitions.
• Genetic factors influencing circadian rhythms may impact depression severity discrepancy.

Purpose of the Study:

• To investigate the association between the CLOCK rs1801260 polymorphism and the discrepancy between self-rated (Beck Depression Inventory: BDI) and observer-rated (Hamilton Depression Rating Scale: HDRS) depression severity.
• To examine the influence of this polymorphism on depressive cognitive distortions.

Main Methods:

• Studied 132 bipolar disorder patients with major depressive episodes.
• Assessed depression severity using BDI and HDRS, calculating the BDI-HDRS discrepancy score.
• Analyzed the effect of the rs1801260 polymorphism on the discrepancy score and cognitive distortions using mediation analysis.

Main Results:

• CLOCK rs1801260*C allele carriers displayed significantly higher BDI-HDRS discrepancy scores compared to T/T homozygotes.
• Depressive cognition of "hopelessness" fully mediated the relationship between the rs1801260 polymorphism and the BDI-HDRS discrepancy.

Conclusions:

• Biological clock-related genetic factors can influence psychopathological features in mood disorders.
• The CLOCK rs1801260 polymorphism's effect on depression severity discrepancy is mediated by hopelessness.
• Further research into other gene polymorphisms is warranted.