Objective: Familial occurrence of tardive dyskinesia (TD) and schizophrenia has been hypothesized to confer risk to the development of TD. We investigated these hypotheses in a large patient sample applying standardized methods for phenotype characterization.
Method: Two hundred and twenty-two patients with a diagnosis of schizophrenia or schizoaffective disorder were assessed for TD and for family history of schizophrenia or schizoaffective disorder. Thirty-nine patients had 40 affected first-degree family members, one patient having two first-degree relatives. Of these, 17 pairs and one triplet were personally examined.
Results: 1) There was a tendency for TD in the affected relatives to be associated with the TD status of the index-patient; this finding was unrelated to age and doses of neuroleptic medication. 2) No association between a family history of schizophrenia or schizoaffective disorder and TD was found.
Conclusion: A family history of TD might represent a risk factor for TD, whereas a family history of schizophrenia does not.