Montserrat Corral

Education and Dementia: A Meta-Analytic Study

Considerable controversy exists about the role of education in the risk of dementia. Individual studies have not been conclusive so far. To examine the hypothesis that lower education is associated with a higher risk of dementia, we carried out a meta-analysis. Observational studies published as of October 2005 that examined the association between education and risk of dementia were systematically reviewed. Relative risks (RRs) and odds ratios were extracted from cohort and case-control studies. We first compared the risk of dementia in subjects with high level of education with the risk of dementia in those with low educational level. In a subsequent analysis, we compared the risk of persons with high education with the risk of subjects with education level other than high (medium, low). We weighted log RRs for cohort studies or odds ratios by the inverse of their variances. Nineteen studies were included in our meta-analysis (13 cohort and 6 case-control studies). RRs for low versus high education level were: Alzheimer’s disease (AD) 1.80 (95% CI: 1.43–2.27); non-AD dementias, 1.32 (95% CI: 0.92–1.88), and all dementias 1.59 (95% CI: 1.26–2.01). For low and medium versus high education level, the RRs were: AD 1.44 (95% CI: 1.24–1.67); non-AD 1.23 (95% CI: 0.94–1.61), and all dementias 1.33 (95% CI: 1.15–1.54). These results confirm that low education may be a risk factor for dementia, especially for AD.

Executive functioning and alcohol binge drinking in university students

BACKGROUND Binge drinking (BD) is prevalent among college students. Studies on alcoholism have shown that the prefrontal cortex is vulnerable to the neurotoxic effects of alcohol. The prefrontal cortex undergoes both structural and functional changes during adolescence and young adulthood. Sex differences have been observed in brain maturation and in alcohol-induced damage. The objective of the present study was to analyze the relationship between BD and cognitive functions subserved by the prefrontal cortex in male and female university students. METHODS The sample comprised 122 undergraduates (aged 18 to 20 years): 62 BD (30 females) and 60 non-BD (29 females). Executive functions were assessed by WMS-III (Backward Digit Span and Backward Spatial Span), SOPT (abstract designs), Letter Fluency (PMR), BADS (Zoo Map and Key Search) and WCST-3. RESULTS BD students scored lower in the Backward Digit Span Subtest and generated more perseverative responses in the SOPT In relation to interaction BD by sex, BD males scored lower in the Backward Digit Span test than BD females and non-BD males. CONCLUSIONS BD is associated with poorer performance of executive functions subserved by the dorsolateral prefrontal cortex. The results do not support enhanced vulnerability of women to alcohol neurotoxic effects. These difficulties may reflect developmental delay or frontal lobe dysfunction.

Reduced anterior prefrontal cortex activation in young binge drinkers during a visual working memory task.

Working memory (WM) is a major cognitive function that is altered by chronic alcohol consumption. This impairment has been linked to alterations in the hippocampus and prefrontal cortex (PFC). Animal and human studies have shown that the adolescent brain is more sensitive to the neurotoxic effects of alcohol than the adult brain, particularly those structures that mature late on in development, such as the hippocampus and prefrontal brain. The aim of the present study was to assess visual working memory and its neural correlates in young university students who partake in intermittent consumption of large amounts of alcohol (binge drinkers). A sample of 42 binge drinkers and 53 corresponding control subjects performed an identical pairs continuous performance task (IP-CPT) in a combined event-related potential (ERP) and exact low-resolution brain electromagnetic tomography (eLORETA) study. The results revealed that, despite adequate performance, binge drinkers showed a smaller late positive component (LPC) associated with hypoactivation of the right anterior prefrontal cortex (aPFC) for matching stimuli, in comparison with control subjects. These findings may reveal binge drinking-related functional alteration in recognition working memory processes and suggest that impaired prefrontal cortex function may occur at an early age in binge drinkers.

Hyperactivation of right inferior frontal cortex in young binge drinkers during response inhibition: a follow-up study.

AIMS The objective of this study was to examine brain activity, with particular attention to prefrontal function, during response execution and inhibition in youths who have engaged in binge drinking (BD) for at least 2 years. DESIGN Event-related potentials (ERPs) were recorded twice within 3 years, during performance of a Go/NoGo task. SETTING The study was part of a longitudinal study of the neurocognitive effects of BD. PARTICIPANTS A total of 48 undergraduate students, 25 controls (14 females) and 23 binge drinkers (10 females), with no personal or family history of alcoholism or psychopathological disorders. MEASUREMENTS The Go-P3 and NoGo-P3 components of the ERPs were examined by principal component analysis and exact low-resolution tomography analysis (eLORETA). FINDINGS Binge drinkers showed larger Go-P3 amplitudes than controls in the first and second evaluations (P = 0.019). They also showed larger NoGo-P3 amplitude in the second evaluation (P = 0.002). eLORETA analyses in the second evaluation revealed significantly greater activation of the right inferior frontal cortex (rIFC) in binge drinkers than in controls during successful inhibition (P < 0.05). CONCLUSIONS Young binge drinkers appear to show abnormal brain activity as measured by event-related potentials during response execution and inhibition which may represent a neural antecedent of difficulties in impulse control.

Binge drinking trajectory and neuropsychological functioning among university students: A longitudinal study

BACKGROUND Adolescence is a time of considerable neurodevelopment. Binge drinking (BD) during this period increases the vulnerability to its neurotoxic effects. This longitudinal study aimed to investigate the relationship between BD trajectory over university years and neuropsychological functioning. METHODS Cohort-study. Two-year follow-up. A total of 89 university students were assessed: 40 Non-BD (at Initial and Follow-up), 16 Ex-BD (BD at Initial but not at Follow-up) and 33 BD (at both times). Neuropsychological assessment of working memory, episodic memory and executive abilities was carried out during their first (Initial) and third (Follow-up) academic year at the University of Santiago de Compostela. RESULTS BD subjects performed less well on the Wechsler Memory Scale-III (WMS-III) Logical Memory Subtest (immediate theme recall, P=.034; delayed theme recall, P=.037; and percent retention, P=.035) and committed more perseverative errors on the Self-Ordered Pointing Task (SOPT) (P=.021) than Non-BD. There were no differences between Ex-BD and Non-BD. CONCLUSIONS Binge drinking trajectory during adolescence is associated with neuropsychological performance. Persistent BD, but not Ex-BD, is associated with verbal memory and monitoring difficulties. This is compatible with the hypothesis that heavy alcohol use during adolescence may affect cognitive functions that rely on the temporomesial and dorsolateral prefrontal cortex.

Impact of Alcohol Use on Inhibitory Control (and Vice Versa) During Adolescence and Young Adulthood: A Review

AIMS Adolescence is usually the time when individuals first drink alcohol and this has been associated with relatively weak or immature inhibitory control. This review examines the changes on brain development and inhibitory function that take place during adolescence and youth as well as the relationship between inhibitory control and alcohol use at this early age. METHODS Narrative review of the chief studies related to (a) the development of inhibitory control during adolescence, (b) the deficits in the inhibitory ability in alcohol use disorders and (c) the effects of acute alcohol intake and binge drinking on inhibitory control in adolescents and young adults. RESULTS Inhibitory control processes are developing during adolescence and youth. Poor inhibitory functions may predispose the individual to alcohol misuse. Likewise, acute and binge alcohol drinking may impair the inhibitory control and compromise the ability to prevent or stop behaviour related to alcohol use. CONCLUSION Poor inhibitory control can be both the cause and the consequence of excessive alcohol use. Adolescence and young adulthood may be a particularly vulnerable period due to (a) the weak or immature inhibitory functioning typical of this stage may contribute to the inability of the individual to control alcohol use and (b) alcohol consumption per se may alter or interrupt the proper development of inhibitory control leading to a reduced ability to regulate alcohol intake. Further longitudinal research is needed to evaluate the interaction between inhibitory control dysfunction and alcohol use in both situations.

Effects of a Persistent Binge Drinking Pattern of Alcohol Consumption in Young People: A Follow-Up Study Using Event-Related Potentials

AIMS The objective of this study was to examine brain activity related to visual attention processes in youths who had maintained a binge drinking (BD) pattern of alcohol consumption for >2 years. METHODS The participants were 57 university students (26 binge drinkers: BDs) with no personal or family history of alcoholism or psychopathological disorders in first-degree relatives. Event-related potentials (ERPs) were recorded while participants performed a visual oddball task (twice within a 2-year interval). The latency and amplitude of the P3b component of the ERPs were analysed. RESULTS The P3b amplitude was larger in young BDs than in aged-matched controls at both evaluation times, and the difference was more pronounced after 2 years of maintenance of a BD pattern of consumption. The larger P3b amplitude was associated with an earlier onset of regular drinking and with a greater quantity and intensity of consumption. CONCLUSIONS These findings suggest that young BDs exhibit anomalies in neural activity involved in attentional/working memory processes, which increase after 2 years of maintenance of BD. This anomalous neural activity may reflect underlying dysfunctions in neurophysiological mechanisms as well as the recruitment of additional attentional/working memory resources to enable the binge drinkers to perform the task adequately.

Binge Drinking and Declarative Memory in University Students

BACKGROUND Binge drinking (BD), which is characterized by sporadic consumption of large quantities of alcohol in short periods, is prevalent among university students. Animal studies have shown that BD is associated with damage to the hippocampus, a region of the brain that plays a key role in learning and memory. The temporal cortex undergoes structural and functional changes during adolescence. The aim of the present study was to examine the association between BD and declarative memory in male and female university students. METHODS The participants were 122 students (between 18 and 20 years of age): 62 BD (30 women) and 60 non-BD (29 women). The neuropsychological assessment included the Rey Auditory Verbal Learning Test (RAVLT) and Weschler Memory Scale-3rd ed. (WMS-III) Logical Memory subtest, to evaluate verbal declarative memory, and the WMS-III Family Pictures subtest, to measure visual declarative memory. RESULTS The BD students remembered fewer words in the interference list and displayed greater proactive interference in the RAVLT; they performed worse in the Logical Memory subtest, both on immediate and delayed recall. There were no differences between the groups in performance of the Family Pictures subtest. No significant interactions were observed between BD and sex. CONCLUSIONS Binge drinking is associated with poorer verbal declarative memory, regardless of sex. The findings are consistent with the vulnerability of the adolescent hippocampus to the neurotoxic effects of alcohol. Longitudinal studies will help determine the nature of this relationship, the neurodevelopmental trajectories for each sex, and the repercussions on academic performance.

Increased amplitude of P3 event-related potential in young binge drinkers.

The aim of the present study was to determine how binge drinking (BD) affects brain functioning in male and female university students during the performance of a visual discrimination task. Thirty two binge drinkers and 53 controls (non binge drinkers), with no history of other drug use, personal or family history of alcoholism or psychopathological disorders, were selected. Event-related potentials (ERPs) were recorded during the performance of a visual oddball task. The latency and amplitude of the N2 and P3b components of the ERPs were analyzed. There were no differences between the groups in behavioral measures, but P3b amplitudes were significantly larger in binge drinkers than controls. This may suggest the presence of anomalies in neural processes mediating attention processing, or an imbalance (increased) of neuronal activity in P3b generators caused by the presence of BD pattern for a long time.

Evolution of the binge drinking pattern in college students: neurophysiological correlates

It is well known that alcohol impairs response inhibition and that adolescence is a critical period of neuromaturation where cognitive processes such as inhibitory control are still developing. In recent years, growing evidence has shown the negative consequences of alcohol binge drinking on the adolescent and young human brain. However, the effects of cessation of binge drinking on brain function remain unexplored. The objective of the present study was to examine brain activity during response execution and inhibition in young binge drinkers in relation to the progression of their drinking habits over time. Event-related potentials (ERPs) elicited by a Go/NoGo task were recorded twice within a 2-year interval in 57 undergraduate students (25 controls, 22 binge drinkers, and 10 ex-binge drinkers) with no personal or family history of alcoholism or psychopathological disorders. The results showed that the amplitude of NoGo-P3 over the frontal region correlated with an earlier age of onset of regular drinking as well as with greater quantity and speed of alcohol consumption. Regression analysis showed that NoGo-P3 amplitude was significantly predicted by the speed of alcohol intake and the age of onset of regular drinking. The group comparisons showed that, after maintaining a binge drinking pattern for at least 2 years, binge drinkers displayed significantly larger NoGo-P3 amplitudes than controls, whereas ex-binge drinkers were in an intermediate position between the two other groups (with no significant differences with respect to controls or binge drinkers). These findings suggest that binge drinking in young people may impair the neural functioning related to inhibitory processes, and that the cessation of binge drinking may act as a brake on the neurophysiological impairments related to response inhibition.