Working memory capacity and addiction treatment outcomes in adolescents

Age-related cognitive decline is accelerated in alcohol use disorder

This study aimed to examine potential cognitive impairments in patients with alcohol use disorder (AUD), and explore the factors affecting them. We recruited 97 inpatients with AUD, showing superficially normal cognitive function (mini-mental state examination score ≥24) for this study. We assessed cognitive function after a 4-week post-abstinence period using the Brief Assessment of Cognition in Schizophrenia-Japanese version (BACS-J). Relationships between BACS-J subcategory/composite raw scores and Z-scores (deviation from standard data in healthy Japanese) and background factors such as age, sex, education, smoking status, mini-mental state examination score, body mass index, systolic blood pressure, severity of depression, alcohol consumption, and laboratory findings were analyzed. Multiple regression analysis showed that the age (p < 0.001) and total bilirubin level (p = 0.014) were worsening factors for the BACS-J composite raw score, whereas education (p < 0.001) was a protective factor. An inverse correlation was apparent between the age and the composite Z-score of the BACS-J (r = -0.431, p < 0.001). Receiver operating characteristic (ROC) analysis identified 53 years as the cutoff age for predicting more than -2SD cognitive decline from the normal standard, with a high negative predictive value (95%). Patients with AUD aged ≥53 years showed more pronounced impairments in verbal memory, working memory, verbal fluency, and attention than those younger than 53 years (p < 0.05). These findings clearly demonstrate accelerated age-related cognitive decline in patients with AUD, especially those aged ≥53 years, suggesting the necessity of early intervention in patients with AUD to prevent progressive cognitive impairment and preserve their quality of life.

Effects of working memory on naturally occurring cravings

Elaborated Intrusion (EI) theory posits a key role for visuospatial working memory (WM) in craving. In line with the predictions of EI theory, several studies have found that WM and craving show mutually interfering effects - for example, performance of visuospatial WM tasks has been found to attenuate naturally occurring cravings. However, the extent to which these effects are driven specifically by visuospatial processing remains unclear. We conducted two experiments to investigate the effects of WM on naturally occurring cravings in more detail. In experiment 1, we examined whether such effects are driven specifically by visuospatial WM processes or can also be induced by a verbal WM task. Subjective craving ratings were attenuated equally by performance of visuospatial and verbal WM tasks, suggesting that craving is not dependent specifically on visuospatial processing. In experiment 2, we examined whether effects of visuospatial WM on craving could be driven by simple distraction. Naturally occurring cravings were attenuated in a control condition with minimal WM demands (watching a video). However, the magnitude of attenuation was significantly greater in a visuospatial WM condition. Taken together, these findings highlight a key role for WM in the attenuation of naturally occurring craving, but do not support the hypothesis that such effects are dependent specifically on visuospatial processing.

Alcohol Consumption during Adolescence in a Mouse Model of Binge Drinking Alters the Intrinsic Excitability and Function of the Prefrontal Cortex through a Reduction in the Hyperpolarization-Activated Cation Current

Periodic episodes of excessive alcohol consumption ("binge drinking") occur frequently among adolescents, and early binge drinking is associated with an increased risk of alcohol use disorders later in life. The PFC undergoes significant development during adolescence and hence may be especially susceptible to the effects of binge drinking. In humans and in animal models, adolescent alcohol exposure is known to alter PFC neuronal activity and produce deficits in PFC-dependent behaviors, such as decision making, response inhibition, and working memory. Using a voluntary intermittent access to alcohol (IA EtOH) procedure in male mice, we demonstrate that binge-level alcohol consumption during adolescence leads to altered drinking patterns and working memory deficits in young adulthood, two outcomes that suggest medial PFC dysfunction. We recorded from pyramidal neurons (PNs) in the prelimbic subregion of the medial PFC in slices obtained from mice that had IA EtOH and found that they display altered excitability, including a hyperpolarization of the resting membrane potential and reductions in the hyperpolarization-activated cation current (I_h) and in intrinsic persistent activity (a mode of neuronal firing that is dependent on I_h). Many of these effects on intrinsic excitability were sustained following abstinence and observed in mice that showed working memory deficits. In addition, we found that resting membrane potential and the I_h-dependent voltage "sag" in prelimbic PFC PNs are developmentally regulated during adolescence, suggesting that adolescent alcohol exposure may compromise PFC function by arresting the normal developmental trajectory of PN intrinsic excitability.SIGNIFICANCE STATEMENT Binge alcohol drinking during adolescence has negative consequences for the function of the developing PFC. Using a mouse model of voluntary binge drinking during adolescence, we found that this behavior leads to working memory deficits and altered drinking behavior in adulthood. In addition, we found that adolescent drinking is associated with specific changes to the intrinsic excitability of pyramidal neurons in the PFC, reducing the ability of these neurons to generate intrinsic persistent activity, a phenomenon thought to be important for working memory. These findings may help explain why human adolescent binge drinkers show performance deficits on tasks mediated by the PFC.