Thiamine (vitamin B1), particularly in its active form thiamine diphosphate (also called thiamine pyrophosphate), is scientifically validated for use in treating certain types of confusion, especially those associated with thiamine deficiency. The classic clinical scenario is Wernicke encephalopathy, a neurological disorder characterized by confusion, ataxia, and ophthalmoplegia, which arises due to severe thiamine deficiency. This syndrome is most commonly seen in chronic alcohol misuse, malnutrition, or malabsorption syndromes. Thiamine is an essential cofactor for enzymes involved in glucose metabolism, and its deficiency impairs cerebral energy utilization, leading to neuronal dysfunction and the symptoms of confusion and encephalopathy.

Numerous clinical studies and medical guidelines support the use of thiamine supplementation (often in high doses and parenterally) to rapidly reverse confusion and prevent progression to irreversible Korsakoff syndrome. The administration of thiamine is considered standard of care in suspected or confirmed cases of Wernicke encephalopathy, and this is reflected in guidelines from neurology and internal medicine societies. However, there is limited evidence for thiamine supplementation in cases of confusion not related to deficiency; its use in other causes of cognitive impairment or delirium is not supported by robust evidence. Overall, the scientific support for thiamine’s role in treating confusion due to deficiency is strong (evidence rating 4/5).