[Skip to Navigation]
Comment & Response
March 2018

Lithium and Dementia—Reply

Author Affiliations
  • 1Psychiatric Center Copenhagen, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
  • 2Department of Biostatistics, University of Copenhagen, Copenhagen, Denmark
  • 3National Institute of Public Health, University of Southern Denmark, Odense, Denmark
  • 4Health and Medical Sciences, University of Copenhagen, Denmark
JAMA Psychiatry. 2018;75(3):302-303. doi:10.1001/jamapsychiatry.2017.3677

In Reply Two comments by Sachdev and by Uzoigwe et al have addressed influences of latitude and other potential confounding factors in our study on the association between lithium in drinking water and the incidence of dementia.1

There may be a north-south gradient in the prevalence of dementia in Scandinavia, but Denmark is considered too small for such an effect (368 km north to south). Further, there is no north-south gradient in lithium concentration in drinking water in Denmark, but rather an east-west gradient with lower concentrations in the western part of Denmark.2,3 Therefore, our results cannot be explained by latitude of residence. However, other potential confounders cannot be excluded. Nevertheless, sources of lithium intake from diet or bottled water are unlikely to be systematically associated with place of residence and explain our findings. Thus, bioavailability of lithium in diet is less than from water, and bottled water consumption in Denmark is among the lowest in the European Union (20 L per person each year).2

Add or change institution