Verbal fluency consists of semantic and phonemic fluency and is often used to detect verbal ability and executive control (Shao et al., 2014). While research has found general verbal fluency impairments in chronic alcohol use, few studies have examined semantic and phonemic fluency separately (Stavro et al., 2012; Stephan et al., 2017). This meta-analytical study examines the performance of abstinent alcohol-dependent individuals on semantic fluency (categories) and phonemic fluency (letters).

As part of a larger study, two researchers independently searched eight databases, extracted required data, and calculated effect sizes on neuropsychological data in alcohol dependent (AD) individuals. Inclusion criteria for articles were: (a) comparison of abstinent alcohol-dependent patients to healthy controls, (b) matched control group on age, education, or IQ, and (c) standardized neuropsychological testing. Exclusion criteria included: (a) diagnosis of Axis I disorders (other than alcohol dependence), (b) comorbidity with other disorders that impact neuropsychological functioning, or (c) not published or translated into English. A total of 31 articles (AD n=1,080 and HC n=1,090) was analyzed in this study.

Semantic fluency evidenced a statistically significant and medium effect size estimate (g = 0.632, p < 0.001). The heterogeneity for semantic fluency was statistically significant (Q=152.468, df=20, p=0.000). Phonemic fluency evidenced a statistically significant and medium effect size estimate (g = 0.572, p < 0.001). The heterogeneity for phonemic fluency was also statistically significant (Q=236.697, df=24, p=0.000).

Deficits in semantic and phonemic fluency are both associated with alcohol dependence. Although some previous research has reported more frontal lobe impact of alcohol, which would be expected to impact phonemic more readily than semantic fluency, this is not evident in the current data. There are many possible reasons for this failure to observe this dissociation meta-analytically. Some potential reasons include the possibility that alcohol affects multiple regions of the brain, that both these measures are affected by alcohol but miss the subtlety associated with frontal damage, or the likelihood that when studies are aggregated in meta-analysis the heterogeneity results in a regression to the mean effect size. These and other reasons are not mutually exclusive and future research should attempt to examine these and other hypotheses.