Accordingly, a growing number of studies have evaluated alcohol use and abuse as potential risk factors for AD. Although a variety of primary studies suggest that light to moderate alcohol drinking may protect against AD in older adults (Weyerer et al., 2011), recent systematic reviews and meta analyses have concluded that there is disagreement in the field regarding the impact of alcohol consumption on AD, with divergent evidence showing that alcohol: (1) serves a protective role against AD; (2) increases AD risk; and (3) has no association with AD (Hersi et al., 2017; Piazza-Gardner, Gaffud, & Barry, 2013). One source of disagreement may derive from inconsistency in operational definitions of alcohol drinking that include imprecise groupings of patients based on light, moderate, or heavy drinking as variables. Similarly, there is variation in measures used to diagnose AD, which rely partly on inconsistent clinical evaluations ranging from telephone interviews to neurological exam. Overall, validity and consistency of alcohol use and AD diagnostic criteria represent limitations of this research and support the need for standardized clinical and research practices (Piazza-Gardner et al., 2013).
