Reduced Dopamine Transporter Availability and Neurocognitive Deficits in Male Patients with Alcohol Dependence

Abstract

Dopamine plays an important role in the development of alcohol dependence, cognitive dysfunction, and is regulated via dopamine transporter activity. Although dopamine transporter activity is critically involved in alcohol dependence, studies observing this relationship are limited. Thus the current study examined whether dopamine transporter availability is associated with developing of alcohol dependence and cognitive dysfunction. Brain imaging with 99mTc-TRODAT-1 as a ligand was used to measure dopamine transporter availability among 26 male patients with pure alcohol dependence and 22 age- and sex- matched healthy volunteers. The Wisconsin Card Sorting Test (WCST) and Tridimensional Personality Questionnaire (TPQ) were administered to assess neurocognitive functioning and personality traits, respectively. Compared to healthy controls, patients with alcohol dependence showed a significant reduction in dopamine transporter availability (p < 0.001), as well as diminished performance on the WCST (p < 0.001). Dopamine transporter availability was negatively correlated with both total and perseverative WCST errors among healthy controls, but only patients with alcohol dependence showed a positive correlation between dopamine transporter availability and a harm avoidance personality profile. Thus, reductions in dopamine transporter availability may play a pathophysiological role in the development of pure alcohol dependence, given its association with neurocognitive deficits. Moreover, personality may influence the development of pure alcohol dependence; however, additional clinical subgroups should be examined to confirm this possibility.

Incongruent reduction of dopamine transporter availability in different subgroups of alcohol dependence

“…3, Table 4). These results are consistent with our previous study [10] and other studies in human, [45,46] which suggest that striatal dopaminergic function may play an important role in performance on cognitive tests.…”

“…Of the different subgroups we examined, this study found that the pure AD group exhibited the lowest DAT availability compared to that in the AD/MD and control groups. Our results are similar to prior neuroimaging studies in patients with AD, [8,10,11] but differ from those of others. [26,27] …”

“…[32,33] Hence, major depression (MD) is one of the confounding factors in the investigation of DAT availability in patients with AD, but previous brain DAT imaging studies could not exclude these confounding factors. [10,11] In order to evaluate the influence of depressive effects on brain DAT activity, the present study recruited patients with AD/MD and pure AD. Thus, the results of incongruent reduction of DAT availability in different subgroups of AD (positive results in pure AD, and negative results in AD/MD, Table 2) may explain previous controversial results.…”

“…[10,24] TRODAT-1 kits were provided by the Institute of Nuclear Energy Research (Lungtan, Taiwan). All subjects consumed a low-protein diet for 24 h before the 99m Tc-TRODAT-1 injection and SPECT measurement.…”

“…Previous brain imaging studies using single-photon emission computed tomography (SPECT) found a reduction in striatal DAT levels in patients with alcohol dependence (AD). [8–10] In addition, studies using postmortem human whole-hemisphere autoradiography also suggest that DAT density is lower in alcoholics. [11] Depression is a common comorbidity in patients with AD.…”