Impairment of Cognitive Abilities and Decision Making after Chronic Use of Alcohol: The Impact of Multiple Detoxifications

Sabine Loeber; Theodora Duka; Helga Welzel; Helmut Nakovics; Andreas Heinz; Herta Flor; Karl Mann

Disclosures

Alcohol Alcohol. 2009;44(4):372-381. 

In This Article

Abstract and Introduction

Abstract

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.

Introduction

Severe chronic use of alcohol has been consistently associated with neuropsychological impairments with respect to cognitive flexibility, problem solving, decision making, risky behaviour and further aspects of cognitive function (for a review, see Moselhy et al., 2001; more recent studies, for example, by Bechara et al., 2001; Fein et al., 2004; Davies et al., 2005; Noël et al., 2007; Glass et al., 2009). In addition, an association between drinking-related variables (e.g. the frequency and duration of alcohol consumption) and a decline of frontal lobe function of alcohol-dependent patients (e.g. Fein et al., 1990) as well as an association of cognitive impairment with frontal lobe function (Noël et al., 2001; Chanraud et al., 2007) has been reported. Although cognitive deficits may also be a risk factor for the development of drug and alcohol dependence, a longitudinal study by Tapert and Brown (1999) suggested that continued substance involvement in adolescence leads to greater neurocognitive difficulties. Taken together, these findings suggest that chronic alcohol use induces neurotoxicity (Moselhy et al., 2001).

Although a large number of studies have demonstrated cognitive impairment in alcohol-dependent patients, only few studies have assessed the influence of repeated withdrawal from alcohol on cognitive function. With regard to animal studies demonstrating an impairment of cognitive abilities and learning after repeated withdrawal (e.g. Stephens et al., 2001; Borlikova et al., 2006), it is reasonable to suggest that an association between the number of previous detoxifications and cognitive impairment in alcoholic patients should exist. In a recent review, Stephens and Duka (2008) have presented cumulative evidence from animal and human studies for altered function of prefrontal cortex and amygdala as the result of aberrant plasticity induced by repeated periods of alcohol exposure.

While the acute administration of alcohol disrupts glutamatergic neurotransmission by reducing the sensitivity of the NMDA receptor (Lovinger, 1993), the prolonged inhibition of NMDA receptors by ethanol leads to an increase in glutamate release. The cessation of chronic alcohol consumption in combination with glutamate release can result in acute excitotoxicity (Tsai and Coyle, 1998). As the frontal lobes are particularly rich in glutamatergic pathways (Kril et al., 1997), this glutamate-mediated excitotoxicity induced by the withdrawal from alcohol may especially affect frontal lobe function. However, only a few studies have assessed the influence of repeated withdrawal from alcohol on cognitive function. In 1989, Glenn et al. demonstrated that the number of withdrawals (defined as the number of 24-h periods of abstinence following a drinking day in the last year) was affecting both immediate and delayed semantic and figural memory in alcohol-dependent patients. More recently, Duka et al. (2003) provided evidence that the repeated experience of withdrawal (i.e. periods of abstinence under medical supervision) is associated with impaired cognitive function in alcohol-dependent patients in a reward delay task, a Porteus maze task and a vigilance task. The fact that these effects were confounded with the age of starting heavy drinking and the years of problem drinking suggests that susceptibility to cognitive impairment associated with multiple detoxifications increases with an earlier start of regular alcohol use. Further evidence for the impact of withdrawal on cognitive functioning can be derived from a small literature on human adolescents (see Tapert et al., 1999, 2002; Brown et al. 2000) relating recent and lifetime alcohol withdrawal symptoms assessed with the lifetime version of the Customary Drinking and Drug Use Record (Brown et al., 1998) to cognitive deficits especially with regard to performance in tests of visual motor integration, visuoperception and retrieval of verbal and nonverbal information (Brown et al. 2000).

In the present study, the effect of previous detoxifications on cognitive function including performance in a gambling task was examined in order to enhance our knowledge on the impact of withdrawal on cognitive impairment. As not all alcohol-dependent individuals may manifest cognitive impairment depending for example on the severity and chronicity of their dependence (e.g. Fein et al., 1990), we initially compared cognitive functioning of our alcohol-dependent patient group with a sample of healthy controls matched for age, gender and demographic variables. We administered a battery of cognitive tasks sensitive to cognitive abilities related to frontal lobe function including performance in a gambling task (Bechara et al., 2001), general cognitive abilities and memory function. Then we divided the patient group according to the findings of Duka et al. (2003) into a group of patients with two or more previous detoxifications (HI-detox group) and a group of patients with fewer than two previous detoxifications (LO-detox group) and compared performance of these two patient groups. Furthermore, we examined whether cognitive performance improves in early abstinence as described by a number of studies (e.g., Mann et al., 1999; Sullivan et al., 2000; Fein et al., 2006) to provide a further understanding of the time course of recovery of cognitive deficits. In addition, findings from a recent study (Noël et al., 2007) have suggested that impairment in a gambling task might recover under continued abstinence.

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