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Comment & Response
March 2018

Lithium and Dementia

Author Affiliations
  • 1Harcourt House, Sheffield, England
JAMA Psychiatry. 2018;75(3):301. doi:10.1001/jamapsychiatry.2017.4190

To the Editor Kessing et al1 effectively demonstrate an association between lithium concentration in regional water in Denmark and the prevalence of dementia. However, in Denmark, there is a notable geographic variation in lithium concentration, which may act as a confounder.2 A higher concentration of lithium is present in the south of Denmark compared with the north.2 Latitude has been found to correlate with dementia risk. Significantly, decreasing latitude, namely a more southern residence, is associated with a lower risk of dementia.3-5 This has been demonstrated globally and notably in Scandinavian countries.3,5 The mechanism is not entirely clear; however, vitamin D, photo-generated through ultraviolet light, has been implicated.3,4 Hence, a number of potential confounders, including latitude of residence, need to be excluded before an incontrovertible link between lithium and dementia can be established.

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