• Neurologic abnormalities in 21 nonschizophrenic siblings and parents of schizophrenics, 24 DSM-III schizophrenics, and 24 normal "control" subjects were assessed by experienced neurologists blind to the subjects' psychiatric status. Medication artifacts and other neurologic signs likely to be etiologically irrelevant to psychiatric illness were excluded. Psychiatric diagnostic assessments of subjects were made blind to neurologic results. The prevalence of neurologic abnormalities in relatives was significantly greater than in controls, but similar to that among the schizophrenics. Relatives and controls differed even more markedly on signs involving motor system abnormalities of localizing significance. Finally, the relatives showed a suggestive dissociation of psychopathology and neurologic signs. The results appear most consistent with the hypothesis that overt schizophrenia may often result from the combined operation of two independent familial factors—one "psychopathologic," the other "neurologic."
Kinney DK, Woods BT, Yurgelun-Todd D. Neurologic Abnormalities in Schizophrenic Patients and Their FamiliesII. Neurologic and Psychiatric Findings in Relatives. Arch Gen Psychiatry. 1986;43(7):665–668. doi:10.1001/archpsyc.1986.01800070051007