Mary Jo Fitz-Gerald

Auditory and visual P300 event related potentials are not altered in medically and psychiatrically normal chronic marihuana users

Attempts to use Event Related Potentials, particularly the cognitive or P300 evoked potential, as measures of CNS effects of THC use have been infrequent and have produced inconsistent results. We published a pilot study in which psychiatric patient THC users had significantly prolonged auditory P300 latencies and reduced amplitudes as contrasted with non-users. Because psychiatric diagnoses and medication effects could not be controlled, we repeated the study with medically and psychiatrically normal subjects selected with extremely stringent exclusion criteria and screening procedures. P300 latency differences between THC users and controls were not detected. Using all subjects, THC users displayed reduced auditory and visual P300 amplitudes. However, when age differences between THC users and controls were removed, all significant P300 amplitude differences were removed as well. The contaminating effect of using psychiatric patients in THC research is discussed and the importance of using carefully screened normal subjects in studies of neurophysiological abuse drug effects is stressed.

Early and Middle Latency Evoked Potentials in Medically and Psychiatrically Normal Daily Marihuana Users: A Paucity of Significant Findings

The use of evoked potentials to study CNS effects of marihuana (THC) have produced inconsistent findings. Our previous pilot studies suggested that auditory P300 latencies and amplitudes, auditory P50 and somatosensory P30 amplitudes and brainstem auditory evoked potential latencies were altered in THC users. Because these findings were flawed by uncontrolled psychiatric diagnostic and medication variables, we undertook a controlled investigation of screened medically and psychiatrically normal THC users and controls. When age effects were controlled, THC related alterations of brain stem and both auditory and visual P300 responses could not be seen. This report extends our analyses to other auditory, somatosensory and visual evoked potentials. With the possible exception of an elevated auditory P50 amplitude, significant evoked potential correlates to daily THC use were not seen when normals were studied and age effects controlled.

Wernicke's Encephalopathy in a Patient with Hyperemesis Gravidarum

The features of Wernicke’s encephelopathy have been described for over a century, usually a combination of confusion, ocular abnormalities, and ataxia. However, over the years, the vulnerable population to this disorder has been overwhelmingly described as poorly nourished alcohol dependent patients, and this has even lead to automatic thiamine administration to such patients in emergency settings. Unfortunately, this narrowed view of the at-risk patient often leads to a missed diagnosis, as evidenced in this patient who exhibited this syndrome secondary to hyperemesis gravidarum. We hope to remind providers that the disorder is secondary to a nutrional deficiency, and therefore, today’s at-risk population needs to be expanded.