Six weeks of diazepam treatment in normal women: Effects on psychomotor performance and psychophysiology

Effects of a therapeutic dose of diazepam (15 mg daily), administered over a 6-week period, were assessed in nonanxious female volunteers. no acute effects of the 5-mg dose of diazepam on performance were observed, but two types of effects were observed on physiology: (1) direct changes on some measures (e.g., skin conductance) and (2) an absence or attenuation of changes expected on the basis of data obtained with a placebo group. The latter effect was found for systolic blood pressure both initially and again after 6 weeks of medication. When performance measured in the morning prior to the first 5-mg dose was compared with that of the morning prior to the last 5-mg dose, 6 weeks later, two types of impairment were found in the diazepam group: (1) decrements in performance (e.g., digit span) and (2) a failure to show expected improvement (e.g., DSST). Performance impairment due to reduced motivation was ruled out by a motivational component of the test battery. Performance tended to return to predrug levels 2 weeks after discontinuation of medication. When physiology was measured in the morning prior to the first dose of the day, 6 weeks of treatment produced decreases in skin conductance, diastolic blood pressure, and heart rate. Blood pressure and heart rate, but not skin conductance, returned to predrug levels 2 weeks after discontinuation of medication. Results of this study indicate that the long-term effects of diazepam can differ from the acute effects and that both acute and longterm effects can take at least two forms, depending upon the behavior or physiological process measured.