Circadian clock gene polymorphisms may be associated with bipolar disorder and comorbid alcohol abuse or dependence in men, according to the results of a study published in the Journal of Affective Disorders.
Researchers investigated the relationship between the shared genetics of bipolar disorder and alcohol abuse or dependence and the circadian clock gene pathway. The case-control study included 436 people with bipolar disorder, of whom 17% had comorbid alcohol abuse or dependence. The control group was comprised of 417 healthy individuals who had no history of mental illness or substance abuse. Analyses were conducted on 44 single nucleotide polymorphisms of 4 key pathway genes.
After correlation analysis, researchers found the clock polymorphisms ARNTL (rs11600996) and PER3 (rs228642) were associated with an increased risk for bipolar disorder and alcohol abuse or dependence in one group of male patients (odds ratio 1.56; 95% CI, 1.07-2.27; P =.03). In addition, the investigators reported an association between 2 PER3 polymorphisms, rs228682 (P =.03) and rs2640909 (P =.03), and having a family history of an affective disorder.
Primary study limitations included the small sample size and gender disproportion in patient groups.
“We confirmed the existence of the direct link between the clock genes and  comorbid diseases as well as the genetic predisposition for [alcohol abuse or dependence] depending on the gender,” the researchers wrote. “Moreover, [these findings] could be helpful in determining high-risk patients with comorbid alcohol abuse and [help] prepare [an] appropriate prevention program.”
Further studies are needed to fully investigate the possible link among circadian clock gene polymorphisms, bipolar disorder, and alcohol abuse or dependence.
Banach E, Pawlak J, Kapelski P, et al. Clock genes polymorphisms in male bipolar patients with comorbid alcohol abuse. J Affect Disord. 2018;241:142-146.