ABSTRACT
RATIONALE: There is considerable literature showing that opiate use is associated with a range of neurocognitive deficits, including deficits in executive control and episodic memory. However, no study to date has assessed whether these neurocognitive difficulties extend to the ability to mentally time travel into one's personal future. This is a surprising omission given that executive control and episodic memory are considered to be critical for episodic foresight. In addition, opiate-related brain changes have been identified in the neural regions that underlie the capacity for episodic foresight. OBJECTIVE: In the present study, we assessed how episodic foresight is affected in the context of chronic opiate use, as well as the degree to which any deficits are related to difficulties with executive control and episodic memory. METHODS AND RESULTS: Forty-eight long-term heroin users enrolled in an opiate substitution program and 48 controls were tested. The results showed that, relative to controls, the clinical group exhibited significant impairment in episodic foresight but not episodic memory (as indexed by an adapted version of the Autobiographical Interview). For executive function, the clinical group was impaired on only one of three measures (Inhibition). CONCLUSIONS: These data provide important preliminary evidence that episodic foresight might be particularly susceptible to the neurocognitive effects of opiate use, as the difficulties identified were not secondary to more general executive control or episodic memory impairment. Because a number of widely used relapse prevention protocols require the ability to mentally project into the future, these data have potentially important practical implications in relation to the treatment of substance dependence disorders.
Subject(s)
Drug Users , Memory Disorders/diagnosis , Memory Disorders/etiology , Memory, Episodic , Opioid-Related Disorders/complications , Opioid-Related Disorders/diagnosis , Adult , Drug Users/psychology , Executive Function/drug effects , Executive Function/physiology , Female , Humans , Male , Memory Disorders/psychology , Middle Aged , Opioid-Related Disorders/psychology , Time FactorsABSTRACT
BACKGROUND: The compound 3,4-methylenedioxymethamphetamine (MDMA) is a potent monoamine releaser that produces an acute euphoria in most individuals. METHODS: In a double-blind, placebo-controlled, balanced-order study, MDMA was orally administered to 25 physically and mentally healthy individuals. Arterial spin labeling and seed-based resting state functional connectivity (RSFC) were used to produce spatial maps displaying changes in cerebral blood flow (CBF) and RSFC after MDMA administration. Participants underwent two arterial spin labeling and two blood oxygen level-dependent scans in a 90-minute scan session; MDMA and placebo study days were separated by 1 week. RESULTS: Marked increases in positive mood were produced by MDMA. Decreased CBF only was observed after MDMA, and this was localized to the right medial temporal lobe (MTL), thalamus, inferior visual cortex, and the somatosensory cortex. Decreased CBF in the right amygdala and hippocampus correlated with ratings of the intensity of global subjective effects of MDMA. The RSFC results complemented the CBF results, with decreases in RSFC between midline cortical regions, the medial prefrontal cortex, and MTL regions, and increases between the amygdala and hippocampus. There were trend-level correlations between these effects and ratings of intense and positive subjective effects. CONCLUSIONS: The MTLs appear to be specifically implicated in the mechanism of action of MDMA, but further work is required to elucidate how the drug's characteristic subjective effects arise from its modulation of spontaneous brain activity.
