Objective Although Wernicke-Korsakoff syndrome (WKS) is a common condition, diagnosis remains difficult. WKS not associated with alcohol is rare and thought to present differently to alcohol-related WKS. We conducted a systematic review of WKS not related to alcohol to enhance understanding of WKS not related to alcohol and WKS in general.

Methods A systematic review was conducted of case reports, published in English, of Wernicke's encephalopathy and WKS in patients without a history of alcohol-use disorder. Main data sources: MEDLINE, Index Medicus. Eligible cases totaled 623. Publication dates ranged from 1867 to 2014. Comparisons of clinical presentation were made with published data on samples comprising, almost exclusively, alcohol-related WKS.

Results A wide array of illnesses precipitated WKS. When diagnosis of WKS was performed postmortem, non-alcohol-related cases presented a similar number of signs of the classic triad as alcohol-related cases (p=0.662, Cohen's w=0.12) but more signs when diagnosed antemortem (p<0.001, Cohen's w=0.46). The most common sign was altered mental state. Korsakoff syndrome or ongoing memory impairment was reported in 25% of non-alcohol-related WKS, although cognitive status was not explicitly reported in many cases. When duration of memory impairment was reported, 56% had clinically obvious memory impairment lasting beyond the period of acute presentation. Non-alcohol-related WKS was more often associated with female gender, younger age, shorter duration of precipitating illness and better survival rate compared to alcohol-related WKS.

Conclusions Thiamine deficiency in the absence of an alcohol-use disorder can cause the full clinical spectrum of WKS, including chronic cognitive impairment and Korsakoff syndrome.