A twin study of the neuropsychological consequences of stimulant abuse.
BACKGROUND
Previous studies document neuropsychological deficits associated with stimulant abuse, but findings are inconsistent.


METHODS
We identified 50 twin pairs in which only 1 member had heavy stimulant abuse (cocaine and/or amphetamines) ending at least 1 year before the evaluation. The co-twin control research design controls for familial vulnerability and makes it easier to identify neuropsychological deficits that are consequences of stimulant abuse. Subjects were administered an extensive neuropsychological test battery organized into the following 5 functions: attention, executive functioning, motor skills, intelligence, and memory.


RESULTS
Multivariate tests showed that abusers performed significantly worse than nonabusers on functions of attention and motor skills. Within each of these functions, univariate tests showed that abusers performed significantly worse on certain tests of motor skills and attention. In contrast, abusers performed significantly better on one test of attention measuring visual vigilance. Within the abuser group, higher levels of stimulant use were largely uncorrelated with neuropsychological test scores, although a few significant correlations indicated better functioning with more stimulant use.


CONCLUSIONS
With ideal controls, this study demonstrates that deficits in attention and motor skills persist after 1 year of abstinence from stimulant use and raises hypotheses regarding relative strengths on a vigilance task among abusers.
Toomey
Rosemary
R
Department of Psychiatry, Massachusetts Mental Health Center, Harvard Medical School, 02129, USA. rosemary_toomey@hms.harvard.edu
Lyons
Michael J
MJ
Eisen
Seth A
SA
Xian
Hong
H
Chantarujikapong
Sunanta
S
Seidman
Larry J
LJ
Faraone
Stephen V
SV
Tsuang
Ming T
MT
D000328:Adult; D019969:Amphetamine-Related Disorders / Q000175:diagnosis* / Q000235:genetics; D000697:Central Nervous System Stimulants; D019970:Cocaine-Related Disorders / Q000175:diagnosis* / Q000235:genetics; D015897:Comorbidity; D004200:Diseases in Twins / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D011597:Psychomotor Performance; D019966:Substance-Related Disorders / Q000175:diagnosis* / Q000453:epidemiology; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
D000697:Central Nervous System Stimulants