Diazepam produces disinhibitory cognitive effects in male volunteers.
BACKGROUND
Diazepam has well known amnestic and sedative effects but effects on fronto-executive function remain largely uninvestigated, especially on neuropsychologically validated tests of risk taking and orbitofrontal cortex function.


OBJECTIVE
We aimed to determine the impact of diazepam on a variety of executive tasks.


METHODS
The effects of 5, 10 and 20 mg of diazepam on a battery of neuropsychological tests were investigated using a randomised, double blind, placebo-controlled design. Seventy-five adult men were recruited. The Rogers et al. (1999b) test of risk-taking was given along with tasks from the CANTAB battery.


RESULTS
Diazepam impaired performance on the Tower of London test of planning, without influencing visual pattern recognition memory. Subjects who had taken diazepam made more risky choices on the risk-taking task. On two speeded reaction time tasks diazepam impaired discrimination sensitivity and increased the bias to respond.


CONCLUSIONS
In contrast to the well-known sedative effects of diazepam, we demonstrate disinhibitory effects on two speeded reaction time tasks. Our results show that diazepam can impair performance on reaction time tasks both by impairing sensitivity and by increasing the bias to respond. Furthermore diazepam impaired performance on tests of planning and risky decision making that depend predominantly on dorsolateral and orbitofrontal regions of the prefrontal cortex, respectively.
Deakin
J B
JB
University of Cambridge School of Clinical Medicine, Department of Psychiatry, Addenbrooke's Hospital, Box 189, Cambridge, CB2 2QQ, UK.
Aitken
M R F
MR
Dowson
J H
JH
Robbins
T W
TW
Sahakian
B J
BJ
D000328:Adult; D014151:Anti-Anxiety Agents / Q000009:adverse effects / Q000494:pharmacology*; D001288:Attention / Q000187:drug effects; D003071:Cognition / Q000187:drug effects*; D003657:Decision Making / Q000187:drug effects; D003975:Diazepam / Q000009:adverse effects / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010364:Pattern Recognition, Visual / Q000187:drug effects; D011340:Problem Solving / Q000187:drug effects; D011597:Psychomotor Performance / Q000187:drug effects; D011930:Reaction Time / Q000187:drug effects
D014151:Anti-Anxiety Agents; D003975:Diazepam