But he said the detrimental effect on cognition could be due to be attributable to poor heart and lung function affecting the brain, or directly harmful effects of smoking on brain - as well as lung - tissue.

BBC: NEWS | Health | Smoking 'is bad for your brain'

Patients in a phase III trial for tarenflurbil, a drug that showed promise in an earlier phase II trial, did not experience improvement in cognition or daily function compared with those who received a placebo, according to a recent study in the Journal of the American Medical Association.

CNN: Nutritional drink, imaging show promise for Alzheimer's