Psychometric schizotypy modulates levodopa effects on lateralized lexical decision performance.
Emergence of psychotic thought has been related to a breakdown in left-hemisphere language dominance. Dopamine (DA) is implicated in both psychotic pathology and modulation of the semantic system. The present study explored whether controlled DA administration modulates basic language functions: (1) in general and/or (2) as a function of schizophrenia-associated thought. Forty healthy men performed a tachistoscopic lexical decision task. Participants' performance was also analyzed as a function of their positive (magical ideation, MI) and negative (physical anhedonia, PHYSAN) schizotypal features. Half of the subjects received 200 mg levodopa, the other half a placebo. Our findings showed that pharmacological treatment per se did not influence task performance, but influenced laterality patterns as a function of participants' schizotypal features. In the placebo, but not in the levodopa group, right hemisphere language contribution increased as a function of increasing MI scores. In the levodopa, but not in the placebo group, superior left hemisphere lexical decision performance was related to increasing PHYSAN scores. The findings from both substance groups suggest that in the healthy brain, a DA agonist restores left-hemispheric dominance for language by reducing right-hemispheric contribution with respect to a positive schizotypal trait and by increasing left-hemispheric specialization with respect to a negative schizotypal trait. We conjecture that the healthy brain compensates through intact neurochemical mechanisms an increased DA concentration, in particular for persons with elevated positive psychotic-like features.
Mohr
Christine
C
Department of Neurology, Functional Brain Mapping Laboratory, University Hospital Geneva, Rue Micheli-du-Crest 24, 1211 Geneva 14, Switzerland. christine.mohr@bristol.ac.uk
Krummenacher
Peter
P
Landis
Theodor
T
Sandor
Peter S
PS
Fathi
Marc
M
Brugger
Peter
P
D000328:Adult; D001921:Brain / Q000378:metabolism / Q000503:physiopathology*; D003072:Cognition Disorders / Q000175:diagnosis; D004298:Dopamine / Q000378:metabolism; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D004311:Double-Blind Method; D007839:Functional Laterality / Q000187:drug effects*; D006801:Humans; D007802:Language; D007980:Levodopa / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D011594:Psychometrics / Q000379:methods*; D012569:Schizotypal Personality Disorder / Q000378:metabolism / Q000503:physiopathology*; D012660:Semantics; D011795:Surveys and Questionnaires; D013850:Thinking
D018491:Dopamine Agonists; D007980:Levodopa; D004298:Dopamine