對於第I型雙相症(英语:bipolarIdisease),其(先証者)發病一致率在同卵雙生子(同卵雙胞胎)中約為40%,在異卵雙生子(異卵雙胞胎)中則為0-10%。從第I型雙相症(英语:bipolarIdisease)、第II型雙相症(英语:bipolar II disease)及循環性情感症的總和來看則為42%
D, Bachi B, Moretti F, Riboldi I, Crocamo C, Carrà G. Repurposed drugs as adjunctive treatments for mania and bipolar depression: A meta-review and critical
Kieseppä, Tuula; Härkänen, Tommi. Lifetime Prevalence of Psychotic and BipolarI Disorders in a General Population. Archives of General Psychiatry. 2007-01-01