Thiamine and brain health: an important factor in preventing cognitive decline

Thiamine (vitamin B1) plays an important role in brain function, yet its deficiency remains one of the most overlooked contributors to alcohol-related neurocognitive disorders. Among these, Wernicke–Korsakoff syndrome stands out as a preventable yet often underdiagnosed condition.

Thiamine deficiency is common in alcohol-dependent patients due to poor dietary intake, impaired absorption, and increased metabolic demand. While healthy individuals absorb about 5% of oral thiamine, absorption drops to roughly 1.5% in those with chronic alcohol use (Haber & Riordan, Guidelines for the Treatment of Alcohol Problems, University of Sydney, 2021).

In Australia, Wernicke-Korsakoff Syndrome affects an estimated 3% of the general population with the highest risk among men over 45 with long history of alcohol dependence (Dementia Australia, Akhouri et al 2023).

Wernicke–Korsakoff syndrome typically begins with Wernicke encephalopathy, an acute neurological state marked by confusion, ataxia, and eye movement disturbances. If left untreated, it can progress to Korsakoff syndrome, a chronic disorder characterised by severe memory loss, confabulation, and irreversible cognitive decline. The classic triad of Wernicke’s encephalopathy is often incomplete, which can lead to under diagnosis and under treatment. (Li S & Xing C (2025). Wernicke encephalopathy. Front. Neurol).

Timely thiamine supplementation is critical. For well-nourished patients, oral thiamine (300mg/day for 1-2 weeks) may be sufficient. However, those with poor nutritional status or alcohol dependence require parenteral thiamine (IV or IM Thiamine 300mg/day for several days, followed by oral thiamine for several weeks). Always give thiamine before any glucose administration to prevent acute neurological deterioration. Long-term oral thiamine (for example, 100mg daily) is recommended for patients who continue to drink (Haber & Riordan, Guidelines for the Treatment of Alcohol Problems, University of Sydney, 2021).

Early recognition and timely thiamine supplementation can mean the difference between full recovery and permanent disability — making awareness and intervention essential in both hospital and community settings.

For advice about management of patients with D&A related issues

• 24/7 telephone advice for NSW health practitioners call DASAS (Drug and Alcohol Specialist Advisory Service) 1800 023 687