Neuroprotective effects of lithium in human brain? Food for thought

Background: There is a growing body of pre-clinical evidence suggesting that lithium (Li) may protect neurons from a range of neurotoxic insults, hence the term neuroprotective effects. Does Li have similar effects also in human subjects? Methods: We reviewed the neuroimaging literature investigating the association between Li treatment and brain structure. Results: There is level I evidence for positive association between Li treatment and brain grey matter volume, which is one of the most replicated neuroimaging findings. It has been reported in the majority of cross sectional studies, all 8 prospective studies, including a randomized controlled trial as well as in 2 meta-analyses and one mega-analysis. The association between Li treatment and grey matter volume occurs regardless of mood state, diagnostic subtype, presence or absence of concomitant medications. It was documented in multiple brain regions, including hippocampus, amygdala, anterior cingulate, subgenual cingulate, inferior frontal gyrus, postcentral gyrus, habenula. Conclusion: Although some methodological and clinical issues complicate the interpretation of findings, there is robust and highly replicated level 1 evidence for positive association between Li treatment and grey matter volumes. These "neuroprotective" effects of Li have been shown even in healthy subjects and appear independent of prophylactic treatment response. Consequently, Li might help maintain brain health even in patients without bipolar disorders and could possibly demonstrate diseasemodifying properties in neurodegenerative disorders.