Influence of personality traits on neuropsychological test performance in toxic encephalopathy cases and healthy referent subjects

The relationship between personality traits and cognitive performance was s tudied in two groups: men with symptoms and neuropsychological test results compatible with toxic encephalopathy (TE) and demographically similar heal thy men (N=57 per group). Personality traits were assessed with the Karolin ska Scales of Personality (KSP). The neuropsychological examination include d 13 tests covering various functional domains. The TE group displayed elev ated scores on all three KSP anxiety scales as well as an elevated impulsiv eness score. Furthermore, the TE group had a lower score on the socializati on scale than did the referent group Different relationships between person ality dispositions and cognitive functioning emerged in the two groups. Wit hin the referent group the highest correlations were observed between KSP a nxiety and socialization scale scores and reaction times measures. This pat tern did not appear in the TE group; instead, divergent and a few weak rela tionships emerged. These relationships involved correlations between the KS P monotony avoidance score and some motor speed scores. By dividing the ref erent group into low anxiety and high anxiety subgroups on the basis of the multi-component anxiety scale score, it was shown that the test scores in the high anxiety subgroup mostly were indistinguishable from the scores in the TE group. In contrast, the low anxiety group had higher test scores tha n the TE group in 8 of the 13 tests. In conclusion, the expected relationsh ip between anxiety and cognitive vigilance is absent in TE cases. This indi cates that the neuropsychological performance decrement in TE cases is not primarily related to elevated mental distress, but is probably dominated by the effects of organic brain impairment. Thus, in TE cases low neuropsycho logical test scores should not be regarded as a consequence of emotional sy mptoms. Furthermore, personality traits may be considered as potential conf ounders even if traditional matching by demographic criteria has been succe ssfully implemented. (C) 2000 Inter Press, Inc.