Vitamin D deficiency linked to increased risk of dementia

New research, highlighted in the media last week, has confirmed that vitamin D deficient older adults have an increased risk of dementia.


In a large population-based study, published in the Journal Neurology, researchers followed 1,658 adults who were participating in the US based Cardiovascular Health Study. All participants were aged 65 or older, did not have dementia at the beginning of the study, and were followed for an average period of six years.

The researchers found that 171 of the participants went on to develop a form of dementia (including 102 who developed Alzheimer's disease). Blood samples taken at the beginning of the study showed that those with low vitamin D levels (considered low enough to be labelled deficient) were almost twice as likely to develop dementia as those who had adequate levels of Vitamin D.

So how is Vitamin D linked to brain health?

Vitamin D receptors are found throughout the brain, including in areas associated with memory (i.e., the hippocampus). It is known that vitamin D regulates neurotrophin expression and enhances the survival of brain cells. Laboratory studies using cell cultures have also found that vitamin D can stimulate certain brain cells that may play a role in clearing amyloid beta plaques.

Alzheimer's Australia National Research Manager, Dr Chris Hatherly said that studies have shown more than half of the Australian population are Vitamin D deficient, as are up to 95% of people in residential aged care were vitamin D deficiency is associated with an increased risk of falls and fractures.

"This new research has added to a growing body of evidence showing a link between Vitamin D deficiency and dementia risk, however we don't yet know whether vitamin D supplementation can reduce the risk of cognitive decline or dementia. The best way to increase Vitamin D is to spend time outside every day, and while vitamin supplements may have an important role for some people, we recommend consulting a health professional before commencing supplements," Dr Hatherly said.

The researchers now plan to replicate their findings in larger and more diverse populations, and to test the effects of vitamin D supplementation in those with mild cognitive impairment and dementia.



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