With regard to hippocampal functionality, human studies evaluating episodic memory in dependent, long-term abstinent individuals have reported similar findings to those relating to the PFC, but the outcomes of the studies have not been entirely equivocal. For example, multiple studies have reported impaired performance on tasks of episodic memory (105–107), and that “normalization” of episodic memory performance in alcohol-dependent subjects has taken place by 1 year of abstinence (95). However, there is evidence that hippocampal dysfunction remains impaired years after abstinence (5, 108). The potential distinction of these two seemingly disparate findings may be the result of (A) many of the studies not evaluating function beyond 1-year abstinence and (B), as described previously, episodic memory is not entirely exclusive of hippocampal function. Therefore, it is possible that, while episodic memory function returns, other facets of hippocampal function remain perturbed long into abstinence from alcohol. Taken together, the current evidence suggests that the recovery of cognitive functionality in abstinent alcohol-dependent individuals is sensitive to the duration of the abstinence period, with the PFC returning to “normative” levels prior to the hippocampal formation.
