fMRI evidence of compensatory mechanisms during a verbal working memory task in individuals with alcohol use disorders

알코올 사용 장애자의 언어 작업 기억과 관련된 뇌의 보상 기전: fMRI 연구

This study investigated compensatory mechanisms in the brain during a verbal working memory task among people with Alcohol Use Disorders (AUD). A total of 21 college male students participated in the study: eleven AUD participants and 10 normal controls. Study participants were asked to complete the Korean version of the Wechsler Adult Intelligence Scale-III (K-WAIS-III) prior to the fMRI experiment. Verbal 0-back and 2-back tasks were used to assess brain activities of the participants' verbal working memory. Brain scanning was performed on Siemens SONATA 1.5T Scanner while participants were performing the 0-back and 2-back tasks. Within the AUD group, participants with greater dependency to alcohol (based on DSM-IV criteria) in the past 1 year showed lower mean score on the 'Similarities' of the K-WAIS-III (r=-0.63, p<0.05, N=11). The more participants experienced alcohol withdrawal symptoms in the past 1 year, the lower the score they received on the K-WAIS-III 'Picture Arrangement' (r=-0.69, p<0.05, n=11). The fMRI regression results showed that individuals who present greater degree of alcohol dependency symptoms are likely to show greater brain activation in the bilateral middle frontal gyri (BA 9) during the verbal working memory task. The degree of alcohol withdrawal symptoms were associated with increased brain activation in the left superior and middle frontal gyri (BA8), left precentral gyrus (BA 6), and left inferior parietal lobule (BA 40). The study findings showed that the degree of alcohol abuse/dependence and withdrawal symptoms were associated with decreased cognitive function and increased activations in brain regions particularly important for abstract reasoning (BA 9), central executive (BA 9), or spatial storage (BA 40) during a working memory task. Therefore, these results could support previous studies suggesting that the neural system of people with ADD may adopt a brain compensatory mechanism to maintain normal level of cognitive functions.