PubMed2001
Neurological consequences of chronic heroin exposure are poorly known. 38 male patients with current heroin abuse or dependence were examined in withdrawal period that lasted more than 10 days, and were compared with 19 healthy controls. Wisconsin Card Sorting Test (WCST), "Delayed Alternation" Test (DAT), "Tower of London" Test (TLT), Russian version of WAIS (1995) were used. Patients were medicated and medication status was evaluated by psychomotor speed level. Patients with the duration of daily heroin abuse more than 1.5 years performed significantly less effectively TLT solutions as compared with the healthy controls (after Bonferroni correction, p = 0001). Patients with shorter duration of daily heroin abuse had a trend to perform TLT solutions poorer as compared to healthy controls and better than group with longer duration (after Bonferroni correction, p = 0.07 and 0.08). Three groups did not differ by WCST and DAT significantly, and general intelligence was in normal range in three groups. Multiple regression analysis confirmed significant influence of daily heroin abuse duration on TLT performance efficiency in our population (beta = -0.426, p < 0.05) without effect of age, education, IQ, dosage of heroin per day, withdrawal duration and current medication status (psychomotor speed level). Perseverative responses on DAT were significantly related to daily heroin dosages before treatment (beta = 0.405, p < 0.05) and negatively correlated with the withdrawal duration. These data give grounds to suppose, that chronic heroin exposure impairs planning functions of prefrontal cortex (TLT), that can be explained by cumulative neuronal damages of prefrontal cortex and VTA dopamine neurons. That was demonstrated in experimental and morphological studies of opiate addicts who died after opiate overdose. Large doses of heroin can induce more extensive functional impairment with possible involvement of orbit frontal cortex. The latter deficit may be partially reversible during short-term withdrawal.