Sabine Loeber

Aims: Several authors suggest that withdrawal from alcohol could cause neurotoxic lesions in the frontal lobe and thereby affect cognitive function. In line with this, previous studies have demonstrated greater cognitive impairment of alcohol-dependent patients with two or more previous detoxifications (Hi-detox) compared with patients with less than two detoxifications (Lo-detox). The aim of the present study was to investigate whether repeated withdrawal from alcohol affects recovery of cognitive function and is related to relapse. Methods: Forty-eight alcohol-dependent patients (Hi-detox: n = 31, Lo-detox: n = 17) and 36 healthy controls underwent a comprehensive neuropsychological test-battery. Patients were tested after completion of detoxification (T1) and 3 (T2, n = 35) and 6 (T3, n = 28) months after discharge. Healthy controls were tested at T1 (n = 36) and T2 (n = 16). Drinking behaviour was assessed at all times. Results: Patients performed significantly worse than controls at T1 as well as T2 with regard to attention/executive function. Recovery of attention/executive function was observed within the second 3 months after discharge, but the Hi-detox group performed worse than the Lo-detox group. No association with relapse was observed. Conclusion: This study provides first evidence, that repeated withdrawal from alcohol might be associated with reduced brain plasticity as indicated by a delay of recovery from impairment of attention/executive function. However, little evidence was found for a direct influence of cognitive impairment on treatment success.

Aims: In the present study, the effect of previous detoxifications on prefrontal function and decision making was examined in alcohol-dependent patients. Further, we examined whether the length of abstinence affects cognitive function. Methods: Forty-eight alcohol-dependent patients were recruited from an inpatient detoxification treatment facility and cognitive function was compared to a control group of 36 healthy controls. The patient population was then divided into a group of patients with less than two previous detoxifications (LO-detox group, n = 27) and a group of patients with two or more previous detoxifications (HI-detox group, n = 21) and cognitive function was compared. In addition, cognitive function of recently (i.e. less than 16 days; median split) and longer abstinent patients was compared. We assessed prefrontal function, memory function and intelligence. Results: Alcoholics, when compared to healthy controls, performed worse with regard to the performance index Attention/Executive function. Cognitive impairment in these tasks was pronounced in recently abstinent patients. We found no significant differences between HI-detox and LO-detox patients with regard to the Attention/Executive function. However, in the IOWA gambling Task, the HI-detox group seemed to be less able to learn to choose cards from the more advantageous decks over time. Conclusions: Our results provide additional evidence for cognitive impairment of alcohol-dependent patients with regard to tasks sensitive to frontal lobe function and underline the importance of abstinence for these impairments to recover. We found only little evidence for the impairing effects of repeated withdrawal on prefrontal function and we suggest that executive function is affected earlier in dependence.

Recent studies demonstrated that alcohol impairs inhibitory control of behavioural responses. We questioned whether alcohol via its disinhibiting effects would also impair the inhibition of an instrumental avoidance response in the presence of a safety signal. Thirty-six moderate social drinkers were randomly allocated to receiving either alcohol (0.8 g/kg) or placebo before performing an instrumental avoidance procedure. White noise of 102 db was used as aversive outcome presented at a variable interval schedule in S+ trials, while no noise was presented in S− trials. An instrumental response (repeated space bar presses to avoid the noise presented at a variable interval) abolished the noise. The Stop Signal task and the affective Go/No-Go task were administered as inhibitory control tasks. Alcohol did not change the avoidance response rate in the presence of S− (safety signal). However, participants under alcohol performed the avoidance response to a lower extent than placebo subjects in S+ trials. Alcohol impaired performance in the Stop Signal task and increased the number of commission errors in the affective Go/No-Go task. Conditioned attentional and emotional responses to the S+ as well as knowledge of stimulus–response outcome contingencies were not affected by alcohol. Acute alcohol may decrease the motivation to avoid negative consequences and thus might contribute to risky behaviour and binge drinking.

It has been suggested that the attention towards alcohol‐related stimuli increases with the duration of drinking and alcohol dependence. The present study aimed to assess whether an attentional bias was present in detoxified alcohol‐dependent patients, and if the magnitude of the attentional bias depended on the subject's drinking history and variables of executive functioning. Attentional bias was assessed in 30 alcohol‐dependent patients using a visual dot‐probe task with a picture presentation time of 50 ms. In addition, patients completed a variety of different cognitive tasks such as attention, continuous performance, working memory, set shifting and inhibitory control tests. Based on correlation analysis we split the patient sample on the median with regard to the duration of alcohol dependence and our results indicated a significant attentional bias towards alcohol‐associated pictures in patients dependent for less than 9 years, but not in patients with a longer duration of dependence. The two patient samples differed significantly with regard to attention and working memory functioning with patients who were dependent for more than 9 years showing a greater impairment. When impairment of attention and working memory were controlled for, the group differences in attentional bias were no longer significant. Our results indicate that differences with regard to drinking‐related variables as well as cognitive functioning seem to modulate attentional bias and need to be taken into account in models of drinking maintenance.