It's been studied in depression, found to have improvements in mood. It's even been studied to improve some forms of cancer progression, which is wild, but makes sense when you think about it, because cancer is probably a metabolic disease. If your mitochondria aren't functioning well, and the mitochondria are where you make ATP, that could have implications for cancer progression. Creatine's also been studied to improve cognition and memory in older adults, especially older adults who have cognitive decline, dementia, this sort of thing. Not surprisingly, creatine supplementation also improves sarcopenia.