Comorbid alcohol dependence disorder may be related to aldehyde dehydrogenase 2 ( ALDH 2 ) and alcohol dehydrogenase 1B ( ADH 1B ) in bipolar II disorder, but only to ALDH 2 in bipolar I disorder, in Han Chinese

Objectives A high prevalence rate of bipolar disorder ( BP ) comorbid with alcohol dependence ( AD ) ( BP + AD ) in Western patients with BP has been reported, but whether this is true for Han Chinese with BP is uncertain. We explored the prevalence of BP + AD in a Han Chinese population with BP , and investigated the effect of alcohol‐metabolizing genotypes on bipolar I disorder ( BP ‐I) + AD and bipolar II disorder ( BP ‐ II ) + AD . Methods Healthy controls ( HC s) (n = 672) and 18‐ to 65‐year‐old patients with BP ( BP ‐I: n = 530; BP ‐ II : n = 788) were recruited. Patients with any other major or minor mental illnesses, neurological disorders, or organic mental disorders were excluded. A polymerase chain reaction and restriction fragment length polymorphism analysis was used to determine genotypes for alcohol dehydrogenase 1B ( ADH 1B) and aldehyde dehydrogenase 2 ( ALDH 2), two alcohol‐metabolizing enzymes. Results AD comorbidity rates were 11.7% with BP ‐I and 17.1% with BP ‐ II . Significantly fewer patients with BP not comorbid with AD ( BP – AD ) carried the AHD 1B*1 allele than did the HC s. Logistic regression analysis showed a main effect of ALDH 2*1/*1 only in the BP ‐I– AD group. In BP + AD patients, logistic regression analysis showed main effects of ALDH 2*1/*1 and ADH 1B*1/*1 only in the BP ‐ II + AD group. Conclusions Having BP ‐ II + AD may be related to ALDH 2 and ADH 1B , but having BP ‐I+ AD may be related only to ALDH 2 . We conclude that ALDH 2 and ADH 1B have different effects in Han Chinese patients with BP ‐I+ AD and BP ‐ II + AD .