In plain terms: Lithium (Low-Dose / Microdose) shows early signals in human research but the evidence is limited -- small trials, surrogate endpoints, or not yet independently replicated. It is an emerging area, not yet a proven one.
Lithium (Low-Dose / Microdose)
The evidence as the record states it
Kessing et al. (Journal of the American Medical Association Psychiatry, 2017; PMID 28832877), Fajardo et al. (2018; PMID 29103043) and Schrauzer & Shrestha (1990; PMID 1699579): population studies linking trace lithium to lower dementia/suicide. Forlenza et al. (2011; PMID 21525519) and Nunes et al. (2013 RCT; PMID 22746245; and 2007, PMID 17401045): microdose lithium RCTs in cognitive decline. Grade C.
Why Grade C and not Grade B
Grade C reflects early or limited human evidence -- small trials, surrogate endpoints, or preliminary findings not yet independently replicated. The evidence points in a promising direction but does not yet meet the standard for Grade B. A single well-powered, independently replicated trial with a meaningful endpoint would move this to Grade B or higher.
What would move this grade
A well-powered randomized trial with an objective, clinically meaningful primary endpoint and at least one independent replication would support Grade B or higher.
How this was studied
Form: Lithium CARBONATE · Dose: Low-dose lithium carbonate as administered in the cited trials · Population: Adults in the cited randomized trials · Duration: As reported by the cited trials · What is sold differs: Lithium orotate and lithium aspartate are what is sold over the counter. Both cited trials used lithium carbonate. No cited trial compares the salts.