Smooth pursuit eye movement dysfunction in abstinent cocaine abusers: effects of a paternal history of alcoholism

The present study evaluated smooth pursuit eye movement (SPEM) function in 36 cocaine-dependent patients, with or without a paternal history of alcoholism, and 12 nondrug-dependent normal volunteers. None of the subjects in either group met DSM-III-R diagnostic criteria for schizophrenia, or delusional, major affective, or schizotypal personality disorders. None possessed a history of seizures, significant head injury, HIV-1 infection, or regular medication use. SPEMs were elicited by a pendulum, oscillated at 0.5 Hz, and recorded using electro-oculographic techniques. Tracking accuracy was estimated by the power of the horizontal electro-oculograph at the stimulus oscillation frequency. Analyses revealed that the SPEM tracking accuracy of cocaine-dependent patients without a paternal history of alcoholism was superior to that of the normal control group. SPEM tracking in these patients correlated positively with years of cocaine and polysubstance abuse. In contrast, patients with a paternal history of alcoholism exhibited subnormal SPEM tracking performance. These differences could not be explained by other family history, demographic, or drug use variables.