MRC Dementias Platform UK Using multi-trajectory analysis to investigate diet (B vitamins) and cognitive change Giovanni Piumatti and John Gallacher Background The role of B vitamins in cognitive performance remains controversial. Using multi-trajectory analysis to integrate micronutrient and cognitive data, we assess the impact of dietary B vitamins on cognitive decline in a general population sample drawn from UK Biobank (N=2975, 51% female, age=40-70 (mean=57.48 years, SD=7.34)). Methods Dietary data (24 hour dietary recall on 4 occasions across 16 months) and cognitive data (two-choice reaction time test administered on two occasions over 4 years, before and after the 4 dietary assessments) were used to characterise dietary B vitamins (B6, B9, B12) and cognitive change. Adopting multi-trajectory analysis we identified B vitamin intake groups. Paired t-tests assessed cognitive change in terms of mean reaction time. Results Two multiple-trajectory groups of B vitamin were identified: a lower vitamins intake group (n=1,910, Mean age=57.19 years, SD=7.37, range 40–70, % women 54), and a higher vitamins intake group (n=1,065, Mean age=58.01 years, SD=7.27, range 40–70, % women 46) (Table 1). B vitamin intake in each group was reasonably constant across waves reflecting usual intake levels (Figure 1). Paired sample t-tests showed that group-based reaction time scores significantly increased over time in the lower intake group only (p<0.001), whilst remaining comparatively stable (p=0.2) in the higher intake group (Figure 2). Conclusion Higher usual dietary B vitamins intake was found to be associated with a slower decline in cognitive performance over 4 years. These findings indicate a protective effect of higher B vitamin intake on processing speed in a comparatively healthy general population sample. Whether this association is causal, or confounded is moot. Trials of B vitamin supplementation and cognition in the cognitively impaired (Zhang et al. doi: 10.1177/0891988716673466) and healthy (Dangour et al. doi: 10.3945/ajcn.115.110775) have not shown benefit. However, they have been small with relatively short follow-up. Our findings reinforce the need for a large trial with a realistic follow-up period to show whether there is benefit from increasing vitamin B intake in low intake groups. Table 1. Descriptive statistics and significant differences between multi-trajectories groups of vitamins B6, B9 and B12 daily intake for sociodemographic and health-related variables (N=2,975) Figure 1. Multi-trajectories groups of vitamins B6, B9 and B12 daily intake (N=2,975). Bayesian Information Criteria (BIC)=-126067.02 (N=35,700 observations), BIC=-126048.38 (N=2,975 persons), Akaike Information Criteria (AIC)=-126003.40, L=-125988.40. Figure 2. Reaction time mean scores at baseline (Time 1) and re-assessment (Time 2) by multi-trajectories groups of folate, vitamins B6, B9 and B12 daily intake (N=2,975). www.dementiasplatform.uk