Comparatively preserved impulse control in late-onset opiate users.

RATIONALE: A substantial literature indicates that in alcohol addiction aspects of impulsive decision-making are typical of individuals with an early onset of addictive behaviour problems. It is not known whether the same applies to opiate addiction, and this insight has important theoretical and clinical implications.
OBJECTIVES: This study aims to examine the relationship between age at onset of addictive behaviour problems and decision-making in opiate addiction.
METHODS: Ninety-three opiate-dependent, treatment-seeking individuals were divided in three groups, early, late and intermediate onset of problems, and completed impulsivity questionnaires and delay discounting and gambling tasks.
RESULTS: Individuals with a late onset of opiate problems (25 years or above) had lower delay discounting rates than individuals with early (18 years or less) or intermediate onset. There were no differences in performance on the gambling tasks. Late-onset individuals were older and had shorter drug histories, but there was no relationship between either age or length of exposure to opiates and delay discounting rates.
CONCLUSIONS: In keeping with previous studies in alcohol addiction, these findings support the notion of at least two distinct subgroups of opiate-dependent individuals, characterised by a different onset of problems, different propensity to impulsive behaviour and perhaps distinct mechanisms leading to addiction.