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Visual memory improved a bit by vitamin D if start with less than 30 ng – RCT Jan 2017

Does high dose vitamin D supplementation enhance cognition?: A randomized trial in healthy adults

Experimental Gerontology, online 4 February 2017, http://dx.doi.org/10.1016/j.exger.2017.01.019
Jacqueline A Pettersen, Northern Medical Program, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia V2N 4Z9, Canada. pettersj at unbc.ca

Highlights

  • Novel trial of high versus low dose vitamin D3 on multiple cognitive domains
  • High dose vitamin D (4000 IU/d) improved nonverbal (visual) memory after 18 weeks.
  • 25(OH)D levels < 75 nmol/L at baseline may confer more benefit with supplementation.
VitaminDWiki Summary

Probably people with > 30 nanograms of vitamin D would have needed more than 4,000 IU to show an improvement
Items of Cognition and Intervention (give Vitamin D and see what happens)

Items of Cognition and Meta-analysis

Alzheimers-Cognition - Overview has the following summary


Background
Insufficiency of 25-hydroxyvitamin D [25(OH)D] has been associated with dementia and cognitive decline. However, the effects of vitamin D supplementation on cognition are unclear. It was hypothesized that high dose vitamin D3 supplementation would result in enhanced cognitive functioning, particularly among adults whose 25(OH)D levels were insufficient (< 75 nmol/L) at baseline.

Methods
Healthy adults (n = 82) from northern British Columbia, Canada (54° north latitude) with baseline 25(OH)D levels ≤ 100 nmol/L were randomized and blinded to High Dose (4000 IU/d) versus Low Dose (400 IU/d) vitamin D3 (cholecalciferol) for 18 weeks. Baseline and follow-up serum 25(OH)D and cognitive performance were assessed and the latter consisted of: Symbol Digit Modalities Test, verbal (phonemic) fluency, digit span, and the CANTAB® computerized battery. Results: There were no significant baseline differences between Low (n = 40) and High (n = 42) dose groups. Serum 25(OH)D increased significantly more in the High Dose (from 67.2 ± 20 to 130.6 ± 26 nmol/L) than the Low Dose group (60.5 ± 22 to 85.9 ± 16 nmol/L), p = 0.0001.

Performance improved in the High Dose group on nonverbal (visual) memory, as assessed by the

  • Pattern Recognition Memory task (PRM), from 84.1 ± 14.9 to 88.3 ± 13.2, p = 0.043 (d = 0.3) and
  • Paired Associates Learning Task, (PAL) number of stages completed, from 4.86 ± 0.35 to 4.95 ± 0.22, p = 0.044 (d = 0.5),

but not in the Low Dose Group. Mixed effects modeling controlling for age, education, sex and baseline performance revealed that the degree of improvement was comparatively greater in the High Dose Group for these tasks, approaching significance: PRM, p = 0.11 (d = 0.4), PAL, p = 0.058 (d = 0.4). Among those who had insufficient 25(OH)D (< 75 nmol/L) at baseline, the High Dose group (n = 23) improved significantly (p = 0.005, d = 0.7) and to a comparatively greater degree on the PRM (p = 0.025, d = 0.6).

Conclusions
Nonverbal (visual) memory seems to benefit from higher doses of vitamin D supplementation, particularly among those who are insufficient (< 75 nmol/L) at baseline, while verbal memory and other cognitive domains do not. These findings are consistent with recent cross-sectional and longitudinal studies, which have demonstrated significant positive associations between 25(OH)D levels and nonverbal, but not verbal, memory. While our findings require confirmation, they suggest that higher 25(OH)D is particularly important for higher level cognitive functioning, specifically nonverbal (visual) memory, which also utilizes executive functioning processes.

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