Aim: The aim was to investigate causes of affective disorders. Evaluation of published medical research revealed that it is still believed that they are largely caused by genes with some environmental input even though there is no evidence to support such beliefs. Psychological research revealed that there are several relevant hypotheses regarding environmental cause.

Hypothesis: Affective disorders are environmentally caused in the physically normal human. Cause is also multifactirial.

Data: Original evidence consisted of three case studies of people known to the author who had already been diagnosed by independent medical personnel as having some type of affective disorder (bipolar and unipolar). Data collection consisted of using qualitative methods including observation and conversation analysis.

Results: Although evidence was limited there is sufficient to conclude that it is likely that affective disorders are caused by the presence of negative social learning (observation) and or conditioning that prevent essential psychosocial need provision and lead to the development of dysfunctional negative schema. The consequence is development of affective disorder behaviours.

Conclusions: More research is needed into psychosocial need provision and schema development that provides enough detail for more definite answers. There is sufficient evidence to make a general finding that all affective disorder cause is environmental and multifactorial.