Blue cone electroretinogram amplitudes are related to dopamine function in cocaine-dependent patients

The objective of the study was to examine the relationship between an index of central dopamine function and electroretinographic (ERG) blue cone amplitudes in cocaine-dependent patients. Thus, 17 recently abstinent cocaine-dependent patients had an ERG performed. They also had a lumbar puncture for determination of cerebrospinal (CSF) concentrations of the dopamine metabolite homovanillic acid (HVA). It was found that patients who had reduced ERG blue cone b-wave amplitudes (<0.5 microV) had significantly lower concentrations of CSF HVA than patients who had ERG blue cone b-wave amplitudes greater than 0.5 microV. There was also a significant positive correlation between ERG blue cone amplitudes and CSF HVA concentrations. These results suggest the possibility that ERG blue cone amplitudes may be a neurobiologic marker related to central dopamine function in cocaine-dependent patients.