تأثیر هالوپریدول بر رابطه عملکرد لوب فرونتال با فقر روانشناختی و سندرم تخریب پذیری

The aim of the study was to examine effects of haloperidol on the relationships between neuropsychological measures of frontal lobe functioning and the schizophrenia syndromes of psychomotor poverty and disorganization. Twenty-one participants with schizophrenia were initially evaluated when clinically stable and chronically treated with haloperidol, and 19 were evaluated again after a 3-week haloperidol-free period. Participants were evaluated with the Trail Making Test, the Wisconsin Card Sorting Test, the Purdue Pegboard, and psychiatric rating scales at each evaluation. There were significant correlations between schizophrenia syndromes and the tests sensitive to frontal lobe function when participants were medicated but not when drug-free. No significant changes in symptom severity or motor function occurred from the medication to the medication-free evaluation. The results indicate that haloperidol mediates the relationship between tests sensitive to frontal lobe function and the schizophrenia syndromes of psychomotor poverty and disorganization. This mediation effect was not attributable to changes in overall symptom severity or motor function.

It has been shown that in patients with schizophrenia, disorganization and psychomotor poverty/anergia syndromes (Liddle, 1987 and Liddle and Morris, 1991) are significantly correlated with cognitive tests assessing frontal lobe function (Himmelhoch et al., 1996). Himmelhoch and coworkers examined the impact of antipsychotic medications on these relationships by comparing a group of patients treated with antipsychotics to a group that was unmedicated. The Trail Making Test, Part B, was significantly correlated with psychomotor poverty and disorganization in medicated but not unmedicated patients. The Wisconsin Card Sorting Test (WCST) (Heaton et al., 1993) was significantly correlated with disorganization in medicated patients, but not in unmedicated patients. These findings suggest that antipsychotic medications may mediate relationships between frontal lobe functioning and symptoms of psychomotor poverty and disorganization. It has also been demonstrated using functional imaging (Liddle et al., 1992 and Ebmeier et al., 1993) that syndrome severity is significantly correlated with the function of specific brain regions. Therefore, differences noted in the correlations between syndrome scores and neuropsychological measures that are associated with medication status (medicated vs. medication-free) may simply result from differences in symptom severity between medicated and unmedicated groups. An additional source of variance that could account for these differences in correlations was that the movement disorder often associated with antipsychotic treatments affected performance, particularly on the Trail Making Test, which has a substantial motor component. The present study was designed to examine the impact of the antipsychotic medication haloperidol on the strength of association between neuropsychological tests sensitive to frontal lobe function and syndromes of disorganization and psychomotor poverty, comparing patients while on and off haloperidol. in making this comparison, we accounted for the influences of generalized symptom severity and drug-induced variation in motor function.