"Our findings suggest that creatine may offer a small-to-moderate benefit for individuals with depression, but average effects were not clinically important and the true effect may be trivial or null. The evidence on which these results are based is very uncertain."
More recently (Nov 2025):
Creatine supplementation for treating symptoms of depression: a systematic review and meta-analysis
https://pubmed.ncbi.nlm.nih.gov/41189312/
"Our findings suggest that creatine may offer a small-to-moderate benefit for individuals with depression, but average effects were not clinically important and the true effect may be trivial or null. The evidence on which these results are based is very uncertain."