Journal Article

Stimulant-induced dopamine increases are markedly blunted in active cocaine abusers

Tomasi, D, Wang, G-J, Volkow, N D, Fowler, J S, Alexoff, D L, Yin, P, Jayne, M, Du, C, Wong, C, Logan, J

2014

Overview

Dopamine signaling in nucleus accumbens is essential for cocaine reward. Interestingly, imaging studies have reported blunted dopamine increases in striatum (assessed as reduced binding of [ 11 C]raclopride to D 2 /D 3 receptors) in detoxified cocaine abusers. Here, we evaluate whether the blunted dopamine response reflected the effects of detoxification and the lack of cocaine-cues during stimulant exposure. For this purpose we studied 62 participants (43 non-detoxified cocaine abusers and 19 controls) using positron emission tomography and [ 11 C]raclopride (radioligand sensitive to endogenous dopamine) to measure dopamine increases induced by intravenous methylphenidate and in 24 of the cocaine abusers, we also compared dopamine increases when methylphenidate was administered concomitantly with a cocaine cue-video versus a neutral-video. In controls, methylphenidate increased dopamine in dorsal (effect size 1.4; P <0.001) and ventral striatum (location of accumbens) (effect size 0.89; P <0.001), but in cocaine abusers methylphenidate’s effects did not differ from placebo and were similar whether cocaine-cues were present or not. In cocaine abusers despite the markedly attenuated dopaminergic effects, the methylphenidate-induced changes in ventral striatum were associated with intense drug craving. Our findings are consistent with markedly reduced signaling through D 2 receptors during intoxication in active cocaine abusers regardless of cues exposure, which might contribute to compulsive drug use.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 692/699/476/5 / Addictions / Alcoholism / Behavioral Sciences / Biological Psychology / Brain - diagnostic imaging / Brain - drug effects / Brain - metabolism / Brain Mapping / Central Nervous System Stimulants - pharmacology / Cocaine / Cocaine - administration & dosage / Cocaine abuse / Cocaine-Related Disorders - diagnostic imaging / Cocaine-Related Disorders - metabolism / Cohort Studies / Control / Craving - drug effects / Craving - physiology / Cues / Detoxification / Dopamine / Dopamine - metabolism / Dopamine D2 receptors / Dopamine D3 receptors / Dopamine Uptake Inhibitors - administration & dosage / Drug addiction / Humans / Intoxication / Intravenous administration / Male / Medicine / Medicine & Public Health / Methylphenidate / Methylphenidate - pharmacology / Middle Aged / Neostriatum / Neurosciences / Nucleus accumbens / original-article / PET imaging / Pharmacotherapy / Positron emission tomography / Psychiatry / Raclopride / Radiopharmaceuticals / Reinforcement / Tomography / Visual Perception - drug effects / Visual Perception - physiology