Mol Psychiatr：长期服用可卡因加速大脑老化

近日有研究表明，长期使用者的大脑年龄大大快于未接触可卡因的人。

英国剑桥大学的科学家的新研究表明：长期滥用可卡因会加速大脑衰老过程。相关研究论文发表在4月25日的Molecular Psychiatry杂志上，该研究发现与健康人群相比，可卡因会让年龄有关的大脑中的灰质损失得更严重。

在这项研究中，研究人员扫描了年龄相近、性别一致以及智商相似的120人的大脑。有一半人依赖可卡因，而其他60人没有药品滥用历史。

研究人员发现，可卡因依赖的人大脑中与年龄有关的灰质的损失率显着高于健康志愿者。可卡因使用者每年失去约3.08毫升的脑容量，这几乎是健康志愿者（只失去了每年约1.69毫升）的两倍。可卡因加速额叶和颞叶皮层中年龄相关的脑容量下降最为突出。

以往的研究表明老年认知功能减退、脑萎缩和免疫相关的心理和生理上的变化与可卡因有关。然而这是第一次证实长期滥用可卡因与大脑过早老化也相关。

英国剑桥大学行为和临床神经科学研究所（BCNI）Karen Ersche医生说：随着年龄的增长，我们都会失去灰质，然而我们所看到的是可卡因长期使用者失去灰质比正常人更显著。灰质损失更快可能是一个过早衰老的迹象。

doi:10.1038/mp.2011.86
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Decreased dopamine activity predicts relapse in methamphetamine abusers

G J Wang, L Smith, N D Volkow, F Telang, J Logan, D Tomasi, C T Wong, W Hoffman, M Jayne, N Alia-Klein, P Thanos and J S Fowler

Studies in methamphetamine (METH) abusers showed that the decreases in brain dopamine (DA) function might recover with protracted detoxification. However, the extent to which striatal DA function in METH predicts recovery has not been evaluated. Here we assessed whether striatal DA activity in METH abusers is associated with clinical outcomes. Brain DA D2 receptor (D2R) availability was measured with positron emission tomography and [11C]raclopride in 16 METH abusers, both after placebo and after challenge with 60?mg oral methylphenidate (MPH) (to measure DA release) to assess whether it predicted clinical outcomes. For this purpose, METH abusers were tested within 6 months of last METH use and then followed up for 9 months of abstinence. In parallel, 15 healthy controls were tested. METH abusers had lower D2R availability in caudate than in controls. Both METH abusers and controls showed decreased striatal D2R availability after MPH and these decreases were smaller in METH than in controls in left putamen. The six METH abusers who relapsed during the follow-up period had lower D2R availability in dorsal striatum than in controls, and had no D2R changes after MPH challenge. The 10 METH abusers who completed detoxification did not differ from controls neither in striatal D2R availability nor in MPH-induced striatal DA changes. These results provide preliminary evidence that low striatal DA function in METH abusers is associated with a greater likelihood of relapse during treatment. Detection of the extent of DA dysfunction may be helpful in predicting therapeutic outcomes.