Our results do not strongly support the prediction that psychiatric “diseases” are more heritable than behavioral disorders. On the one hand, Alzheimer’s Disease and two disease-like conditions, schizophrenia and bipolar disorder, have very high heritabilities. On the other hand, panic, major depressive, and generalized anxiety disorders have substantially lower heritabilities, lower than those of most of the behavioral disorders examined. Thus, there does not appear to be a systematic relationship between the disease-like character of a psychiatric disorder and its heritability. Indeed, idiopathic Parkinson’s Disease, another neuropsychiatric condition with a known histopathology, does not appear particularly heritable (Wirdefeldt et al., 2004).
