Nicotine has been really interesting for Dementia or Alzheimer's so this checks out. The one study I know that is ongoing is mindstudy.org. It's well tolerated, cheap, and widely available.

Not a Doctor but if I had a loved one at-risk or experiencing age-related cognitive impairment, it's probably worth trying rather than waiting for scientific consensus which may take years and will probably be blocked by the FDA so some pharma company can develop patented neuro-nicotine or whatever.