Sometimes I'm Stupid. This is a re-write of my post extolling the virtues of vitamin D3 based on misreading a study and thinking down was up and left was right. I would just delete it but some people have seen it and I want the correction to be here.
This is the trial from 2016 that had me excited: Effects of Vitamin D in Parkinson's Disease (PD) trial results from 2016 clinicaltrials.gov/ct2/show... (his is a poorly named trial as they were actually testing vitamin D plus calcium). It was a 16 week trial with controls giving people vitamin D (10,000 IU daily) and 1000 mg of calcium.
I got excited when I saw the secondary outcome "Change in Cognition (Trail Making Test B-A)" was 12.13 and the placebo was -17.33. But lower scores are better, and to get the result they subtracted the baseline from the 16 week score so a positive number is bad. In this study the people on the vitamin D (and calcium) got worse as far as "Change in Cognition (Trail Making Test B-A)".
I should also point out for those that get excited by small short duration trials, it looks like the placebo did a great job improving cognition! I don't know what the placebo was, only that the "placebo pill with similar appearance to the vitamin D3". (the placebo group did get 1000 mg of real calcium too). ANYWAY, I should not get excited by small studies. The good placebo results highlight how volatile the numbers can be.
Here is a good breakdown of the study in detail. It even has links to the supporting data files: ncbi.nlm.nih.gov/pmc/articl...
And if you would like to read the description of "Change in Cognition (Trail Making Test B-A)":
The Trail Making Test (TMT) consists of two parts (A & B) in which the subject is instructed to connect a set of 25 dots as quickly as possible while still maintaining accuracy. The test provides information about visual search speed, scanning, speed of processing, and executive functioning. Part A measures processing speed and part B measures executive functioning. The TMT is time to complete each part of the test in seconds. Higher scores indicate greater impairment. Subtracting part A from part B is theorized to reduce the influence of the working memory and visuospatial demands and, therefore, provides a relatively pure indicator of executive function. Change score is measurement (Part B - Part A) at 16 weeks minus measurement (Part B - Part A) at baseline, negative scores indicate a improvement in executive functioning.