Vitamin B1 is critical for many biochemical reactions involved in normal brain functions. Low levels of B1 is a common condition in older adults and may lead to structural brain changes and cognitive impairment, although the evidence has been mixed  and very few studies have investigate the relationshops with cerebrospinal fluid (CSF) biomarkers of Alzheimer’s disease such as CSF Aβ42 and total tau.

A sample of 462 patients aged 40-94 years who referred to the memory clinic of the Ulm University Hospital in Germany were included. The examination was carried out between December 2009 and August 2015, a CSF-examination was performed in 227 individuals. Dementia was diagnosed according to the DSM-IV criteria. CERAD battery was used to examine the cognitive status, and different domains such as episodic memory, executive functioning, semantic memory, visuoconstructive praxis, and global cognition were derived
High performance liquid chromatography was used for measuring vitamin B1 and Photometrie was used to assess TPP and ETKA. CSF Aβ42 and total tau were measured using cusing an enzymatic immunoassay method. Regression models were used to investigating the associations with CSF biomarkers and cognitive functioning. 

Raised values of vitamin B1 and a better ETKA-TPP profile were related to better performance in several cognitive domains such as episodic memory, verbal fluency and global cognition. No associations were found between any of the vitamin B1 markers and CSF biomarkers of Alzheimer's disease.

Markers of vitamin B1 may be independent predictors of cognitive functioning. Prospective studies with a long follow-up duration are needed to establish the temporality of the associations and randomized controlled trials are needed to esbalish the causality.