Nobody knows. A recent report out of Germany suggests that pioglitazone does prevent dementia, but it’s not a very strong linkage. If it works, I wonder if it’s simply related to better control of blood sugar, which could be accomplished with a variety of means. Pioglitazone (aka Actos) is a type 2 diabetes drug in the TZD class. You could call it an “insulin sensitizer.”
German researchers went fishing for associations in a huge database of patients and drug usage. Their formal report hasn’t even been published yet. A five-year study was recently initiated to further investigate the possibility that piogoitazone prevents dementia. I doubt this will pan out.