Circadian phenotype in patients with the co-morbid alcohol use and bipolar disorders.

AIMS Alcohol misuse is associated with bipolar disorder. Abnormalities in the circadian clockwork play a role in the pathogenesis of bipolar disorder. Alcohol intake is likely to affect the circadian phenotype. We aimed at analysing the behavioural trait of the preference to morning or evening hours for the daily activities in bipolar disorder patients with or without the co-morbid alcohol use. METHODS Our nationwide sample of families included patients with bipolar disorder born during 1940-1969 having at least one hospitalization due to bipolar disorder during 1969-1991 and their first-degree relatives. All the 148 participants were interviewed using the Structured Clinical Interview for DSM-IV Axis I Disorders and assessed using the Morningness-Eveningness Questionnaire whose factor matrix applying for the maximum likelihood principle was calculated for the first time. RESULTS Patients with the co-morbid alcohol use disorder were more of the morning type as compared with patients with bipolar disorder only. CONCLUSIONS Co-morbid patients preferred more the morning hours for their daily activities, indicative of alcohol consumption having an effect on the circadian clock.