Neuropsychological correlates of platelet monoamine oxidase (MAO) activity in female and male subjects.

Platelet monoamine oxidase (MAO) activity has been found to have behavioral (psychiatric and personality) correlates and is assumed to be linked to central transmitter systems and thus presumably to neuropsychological processes. In the present study, computerized neuropsychological tests, a reaction time (RT) test and a visuo-spatial problem solving test, the Perceptual Maze Test (PMT), were given to 32 female and 29 male students, each sex group divided into three subgroups on the basis of platelet MAO activity. The tests yield measures of laterality (reaction time for left- versus right-sided stimuli) and different aspects of cognitive strategy and skill, e.g. time used for inspection of the maze, for processing the stimulus pattern, and for checking the correctness of solutions. Low MAO female subjects had shorter RTs, pronounced for left-sided stimuli, and shorter inspection times in the PMT compared to other female subjects. Low and high MAO males had difficulties in inhibiting responses, when required, and low MAO males were more rapidly prepared to respond to new stimuli after short intervals than other males. In the PMT, high MAO male subjects spent a smaller part of the total time on inspection in relation to other male groups and had more rubouts than low MAO males, whose maze solving behavior indicated higher visuo-spatial ability. The results are discussed in terms of possible neurochemical bases of impulsivity and psychopathy, and of spatial skill.