Prefrontal correlates of approach preferences for alcohol stimuli in alcohol dependence

Abstract

An approach bias for alcohol stimuli (i.e. faster approach than avoidance reactions) might facilitate relapses in alcohol dependence. Neurobiological models suggest hypersensitivity in the reward system [inter alia nucleus accumbens and orbitofrontal cortex (OFC)] to cause pathologically enhanced approach impulses towards alcohol stimuli. At the same time, in alcohol dependence, these structures are only insufficiently controlled by a hypoactive dorsolateral prefrontal cortex (DLPFC). The present study investigated the cortical aspects of this model with functional near-infrared spectroscopy in 21 alcohol-dependent in-patients and 21 healthy controls (HC; comparable in age, gender and education) during performance of the Approach-Avoidance Task (AAT) for the first time. Complementing previous findings, in reaction times (RTs), patients showed stronger approach preferences for alcohol than non-alcohol stimuli. For non-alcohol stimuli, patients even displayed avoidance preferences. The reversed pattern was found in HC. Group differences in activity of the OFC were identical to those in RTs, revealing patients to assign higher subjective value to approaching alcohol stimuli. In both groups, regulatory activity in the right DLPFC was stronger during avoiding than approaching alcohol pictures. Probable awareness of the behavioural hypotheses due to explicit task instructions and patients' deficient prefrontal function might account for this equally aligned pattern. Results are discussed with regard to recent findings revealing a reduced behavioural approach bias and risk for relapse by applying a retraining version of the AAT. Functional measurements might serve as a method for monitoring the corresponding neurobiological changes and-possibly-predicting the success of such a training.

Addiction and embodiment

“…In the task with explicit instructions, the AAT consists of blocks where participants are asked to push away drug cues and pull neutral cues, and vice versa. For example, Ernst et al (2014) found that alcohol--dependent inpatients are faster in approaching than avoiding alcohol cues on the direct AAT, an effect with a comparable size as found on implicit tasks (e.g., C. E. Wiers et al, 2014). So even though the indirect instruction was initially thought to be advantageous in reducing the controllability of the outcome measure, it does not seem to be a necessary feature for measuring the drug approach bias.…”

“…For example, studies have assessed reactions of avoidance to pictures of spiders , motivational reactions towards pictures of food (Loeber et al, 2011) and drugs (Barkby, Dickson, Roper, & Field, 2012;Ernst et al, 2014), and even implicit attitudes towards race (Stanley, Sokol--Hessner, Banaji, & Phelps, 2011). The tasks that measure these reactions are considered implicit or automatic if the instructions of the task are indirect (i.e., subjects are unaware of what the task measures) or if the outcome measures are reaction times that are fast, goal--independent and not controllable (De Houwer, 2006).…”

“…Though this finding has not been reported in AAT studies, C. E. Wiers et al (2014) found that alcohol craving was correlated with amygdala activations while approaching versus avoiding alcohol cues in alcohol--dependent patients. First insight into neural mechanisms involved in the alcohol approach bias, shows that reward--related brain areas (i.e., the nucleus accumbens, the medial prefrontal cortex and amygdala) were associated with approaching versus avoiding alcohol cues in alcohol--dependence (Ernst et al, 2014;C. E. Wiers et al, 2014).…”

Neural Correlates of Alcohol-Approach Bias in Alcohol Addiction: the Spirit is Willing but the Flesh is Weak for Spirits

“…Recently, activity in the mPFC was shown for the cannabis approach bias in both cannabis users and nonsmoking controls (Cousijn et al, 2012). Moreover, a recent near-infrared spectroscopy study demonstrated that the neighboring orbitofrontal cortex is active when alcoholdependent patients approach alcohol cues (Ernst et al, 2012). Hence, the NAcc and mPFC may have important roles in the drug approach bias.…”

“…Previous research has demonstrated that drug-dependent individuals exhibit an automatically activated tendency to approach rather than to avoid drug cues relative to neutral cues (ie, drug approach bias; Cousijn et al, 2011;Ernst et al, 2012;Wiers et al, 2013;Zhou et al, 2012). The drug approach bias is likely to reflect an embodied motor reaction towards drug cues and has been positively related to subjective rates of drug craving (Wiers et al, 2013).…”