Personality and reactivity to stimulants and depressants.

Abstract

Thirty-one nonpatient male volunteers with four distinct Minnesota Multiphasic Personality Inventory patterns (neurotic triad pattern, psychotic tetrad pattern, elevated Ma and Pd scales, and normal patterns) were selected in order to investigate the differential effect of stimulants and depressants on different personality types. Two stimulants, caffeine sodium benzoate and methylphenidate hydrochloride, and two depressants, secobarbital sodium and amobarbital sodium, were given to various combinations of the four types of subjects in groups seven to ten men. The subject's scores on two cognitive and one motor test following drugs administration were compared. Several significant intergroup differences are reported. The group with the psychotic tetrad pattern was found to be relatively unresponsive to stimulants and sensitive to depressants. Those subjects with the elevated Ma and Pd pattern were generally very responsive to stimulants and more sensitive to depressants than the normal group and the group with the neurotic triad pattern. The group with the neurotic triad pattern was relatively responsive to stimulants, but less sensitive to depressants than subjects with the psychotic tetrad or the elevated Ma and Pd pattern. The results are discussed in terms of Eysenck's theory of drug response based on an extroversion-introversion dimension. The group of subjects with the elevated Ma and Pd profile had personality scores on the MMPI, the CPI and the Maudsley Personality Inventory most suggestive of extroversion. The response of this group to both stimulants and depressants was consistent with Eysenck's predictions. No group appeared to have personality scores suggesting introversion so that complete confirmation of Eysenck's theory could not be made.