Premorbid and current neuropsychological function in opiate abusers receiving treatment.

BACKGROUND: There is an established corpus of evidence linking substance abuse with neuropsychological impairment, particularly implicating frontal lobe functions. These could potentially be premorbid to, rather than consequences of, direct effects of substance abuse.
METHODS: A matched pairs design was employed in which currently abstinent opiate abusers in treatment were matched to 22 healthy control individuals. These were compared for premorbid and current neurobehavioral abnormalities with the self-report Frontal Systems Behavior Scale (FrSBe). Estimated premorbid and current IQ scores were also ascertained.
RESULTS: There was no difference between the groups regarding socioeconomic background. There was no evidence for an alteration in cognitive function as measured by current IQ associated with opiate abuse, nor evidence of premorbidly lower IQ. However, with the FrSBe, the opiate abusers reported overall higher levels of apathy. They also had raised FrSBe total scores, indicating the presence of neurobehavioral features associated with frontal lobe impairment. Furthermore, the opiate abusers reported higher levels of these neurobehavioral abnormalities compared to their matched controls, even in the period preceding substance abuse.
CONCLUSIONS: The results suggest that some substance abusing individuals in treatment demonstrate raised levels of neurobehavioral abnormalities, independently of general intellectual functioning. Furthermore, the results imply that these abnormalities may have already been present prior to the effects on the nervous system of substance abuse.