To assess vitamin D status and its relation to cognition among young adolescents in a northern population.

Vitamin D insufficiency, defined as serum [25(OH)D] <75 nmol/L is common, particularly with increasing latitude. Vitamin D status has been linked to visual memory in adults. We hypothesized that vitamin D status would similarly be associated with visual memory in young adolescents.

Participants included adolescents 9-13 years in northern British Columbia. Cognitive tests performed via videoconferencing included the Rey-Osterrieth Complex Figure Task (ROCF), assessing visual memory, Rey Auditory Verbal Learning Task (RAVLT), assessing verbal learning/memory, Digit Span (Forward, Backward), assessing attention, and a verbal fluency task assessing executive functioning and language. Participants were provided an at-home, mail-in blood spot test to assess [25(OH)D].

The participants (N=56) were 10.7 (SD=1.3) years, with 61% females. Mean [25(OH)D] was 84.2 nmol/L (SD=25.5), ranging from 39.9 to 167.2 nmol/L and 41% had insufficient vitamin D status. Measures of visual memory (ROCF-Recall, -%Recall of Copy) were significantly correlated with 25(OH)D levels, r=.034, p<.01 and r=.033, p<.01, respectively, and [25(OH)D] remained a significant independent predictor of these two cognitive measures on multiple regression analyses, which included age and sex.(ROCF-Recall overall model : Adj R²=.24, p<.001; for 25(OH)D: p=.009; ROCF-%Recall of Copy overall model: Adj R²=.20 p<.002; for 25(OH)D: p=.01). Individuals with sufficient vitamin D status performed significantly better than those with insufficient status on these measures (t-tests, p=.016, d=0.68; p=.022, d=0.64). This effect was especially pronounced within the older age group (11-13yrs), d=1.1.

Vitamin D insufficiency was common in these young adolescents. Similar to adults, visual memory was shown to be better among participants with higher [25(OH)D] and those with sufficient levels. This effect was especially pronounced among the older participants, suggesting possible time- and/or age-related implications of vitamin D status on cognition.