Improved short-term spatial memory but impaired reversal learning following the dopamine D(2) agonist bromocriptine in human volunteers.
BACKGROUND
Studies in humans of cognitive effects of dopaminergic drugs have largely focused on tasks of working memory, with a few studies also examining executive function.


OBJECTIVE
This study was designed to investigate the effects of 1.25 mg of the dopamine D(2) agonist bromocriptine on spatial working memory, planning and discrimination reversal learning in young healthy volunteers.


METHODS
Twenty volunteers were tested in a double-blind, placebo-controlled, cross-over design. The cognitive assessment included tests taken from the Cambridge Neuropsychological Test Automated Battery (CANTAB) designed to test visuo-spatial recognition memory and spatial working memory. In addition, tests of spatial planning and discrimination reversal learning were used to assess the more general effects of bromocriptine. Tests of subjective feelings and motivation were also incorporated into the battery.


RESULTS
Bromocriptine enhanced the spatial memory span of subjects, whilst impairing their ability to reverse a learned probabilistic discrimination. Tests of recognition memory and planning were unaffected by the drug. The findings were not explained by changes in subjective mood or motivational measures.


CONCLUSIONS
The pattern of findings observed here mirror medication-dependent observations seen in Parkinson's disease. The results are discussed with reference to the different anatomical networks known to subserve performance of the differentially affected tasks.
Mehta
M A
MA
Department of Psychiatry, University of Cambridge, School of Clinical Medicine, Addenbrooke's Hospital, UK. mitul.mehta2@ic.ac.uk
Swainson
R
R
Ogilvie
A D
AD
Sahakian
J
J
Robbins
T W
TW
D000328:Adult; D000704:Analysis of Variance; D001971:Bromocriptine / Q000494:pharmacology*; D018592:Cross-Over Studies; D018491:Dopamine Agonists / Q000494:pharmacology*; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects* / Q000502:physiology; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000819:agonists*; D012193:Reversal Learning / Q000187:drug effects* / Q000502:physiology
D018491:Dopamine Agonists; D017448:Receptors, Dopamine D2; D001971:Bromocriptine