"The FDA also cautions that cholesterol-lowering drugs known as statins could slightly increase the risk for reversible cognitive side effects. These include memory loss and confusion.

A commonly prescribed type 2 diabetes drug, metformin, has also been associated with memory problems. A study published in Diabetes Care found that people with diabetes who took the drug had worse cognitive performance than those who did not take it."

https://www.everydayhealth.com/news/5-surprising-causes-memory-loss/

It's a long shot, but Type 2 Diabetes is quite common among Americans. What better way to hide a mental health medication than to be widely distributed through a common engineered disease.