B vitamins may not help improve cognitive function
Daily intake of B vitamins did not improve cognitive function in patients with small vessel disease, in addition to previous findings that it was not protective against major vascular events in patients who had a recent stroke or transient ischaemic attack, according to a substudy of the VITATOPS* trial.
The initial aim of the double-blind VITATOPS trial was to investigate the effect of lowering homocysteine level, which has been associated with atherosclerosis and thrombosis, through daily administration of B vitamins.
“Cerebral small vessel disease typically disrupts fronto-subcortical network and produces cognitive profile of impaired attention and executive function,” said the researchers led by Dr Simon Ting Kang Seng, a neurologist from the National Neuroscience Institute and Singapore General Hospital in Singapore.
For the substudy, 230 subjects with cognitive impairment no dementia (CIND) and a recent lacunar stroke out of a total of 8,164 participants in the multinational VITATOPS study were analysed. The participants were randomized to receive either placebo or B vitamins daily containing 25 mg vitamin B6, 2 mg folic acid, and 0.5 mg vitamin B12. They were followed up at 6-month interval for 1–5 years. [J Neurol Sci 2017;379:124-126]
CIND was determined by impairment in ≥1 domain of the neuropsychological test battery, with 1.5 standard deviations below the established normal means as cut-off values adjusted for education in individual tests. Neuropsychological examination included forward and backward digit span as well as visual memory, frontal assessment battery, digit cancellation task, and animal naming. At baseline, both groups demonstrated comparable performance in the tests, while homocysteine level in the B-vitamins group was consistently lower than the placebo group throughout the 5 years.
At all study visits during follow up, change in cognitive function from baseline was not significantly different between the two groups, in terms of global cognition decline as assessed by the mini-mental state examination (p=0.40), forward and backward digit span (p=0.96 and 0.44, respectively), forward and backward visual memory (p=0.50 and 0.87, respectively), frontal assessment battery (p=0.83), digit cancellation task (p=0.25), and animal naming (p=0.77).
The difference between the two groups remained insignificant after adjusting for smoking and ischaemic heart disease.
“Our study suggests that B vitamins probably unlikely participate in process modulating cognitive outcomes (global and fronto-subcortical function) in patients with small vessel disease based on the limited findings,” said the researchers.
“Based on our findings, routine use of long-term B vitamins for the purpose of improving cognitive functions in those with cerebral small vessel disease is probably not recommended.”
Since the substudy cohort came from a single study site of the VITATOPS trial, the researchers said this might contribute to selection bias and caution should be exercised in interpreting the results.