[Reeses]

Vitamin D is needed for healthy bones, not brains. Finding links is easy, showing causation is hard. This is junk science.

[9YearLurker]

Agreed that this report of the study at lewst doesn’t show causation, but D linked to more than just healthy bones.

[Pete from Shawnee Mission]

“Vitamin D is needed for healthy bones, not brains. Finding links is easy, showing causation is hard. This is junk science.”

And that was a dismissive Junk Comment. in addition to bone health, vitamin D acts on a number pathways in the body not only in the overly simplistic way single pathway you suggest.

https://www.webmd.com/diet/guide/vitamin-d-deficiency#1

“Symptoms and Health Risks of Vitamin D Deficiency

Snip...”Symptoms of bone pain and muscle weakness can mean you have a vitamin D deficiency. However, for many people, the symptoms are subtle. Yet, even without symptoms, too little vitamin D can pose health risks. Low blood levels of the vitamin have been associated with the following:

Increased risk of death from cardiovascular disease
Cognitive impairment in older adults
Severe asthma in children
Cancer”