Correlations between cognitive, behavioural and psychological findings and levels of vitamin B12 and folate in patients with dementia

Background: Associations between low levels of folate and vitamin B12 and cognitive impairment in patients with dementia have been reported. Some studies revealed correlations between low levels of vitamin B12 and behavioural and psychological signs and symptoms of dementia (BPSD) in Alzheimer's disease (AD) patients. Given the lack of studies in frontotemporal dementia (FTD) and on folate and given the methodological shortcomings of former publications, we set up a prospective study.

Methods: At inclusion, AD (n=152) and FTD (n=28) patients underwent a neuropsychological examination. Behaviour was assessed using a battery of behavioural assessment scales. Determination of serum vitamin B12 and red cell folate levels were performed within a time frame of two weeks of inclusion.

Results: In both patient groups, significantly negative correlations between levels of serum vitamin B12 and red cell folate and the degree of cognitive deterioration were found. No correlations with BPSD were found in the AD patient group. In FTD patients, levels of vitamin B12 were negatively correlated with both hallucinations (p=0.022) and diurnal rhythm disturbances (p=0.036).

Conclusions: The observed negative correlations between levels of vitamin B12 and folate and cognitive impairment in both AD and FTD patients, raise the possibility of a non-specific etiological role. Although levels of vitamin B12 and folate did not correlate with BPSD in AD patients, negative correlations between serum vitamin B12 levels and BPSD in FTD patients were revealed. Decreased serum vitamin B12 levels may predispose FTD patients to develop hallucinations and diurnal rhythm disturbances.