Familial psychosis and vulnerability to tardive dyskinesia.

The demography, course of illness, cognitive dysfunction and neurological consequences of long term treatment of 11 family pairs with long history of chronic schizophrenic illness were studied. There was concordance for the presence of tardive dyskinesia in 6 pairs; each of 2 brother-brother pairs; 3 brother-sister pairs and one of mother-daughter pair. There was concordance for the absence of tardive dyskinesia in 5 pairs, each of 3 father-son pairs and 2 brother-sister pairs. In schizophrenic patients the presence or absence of tardive dyskinesia in one member of the family is a risk factor for the development of the syndrome in another member with the same psychotic illness. Those pairs with tardive dyskinesia were characterized by negative symptoms of schizophrenia and evidence of intellectual deterioration.