More "you don't say...."

Combination of smoking and heavy drinking 'speeds up cognitive decline'

Mind you, seems to me the effect is not exactly all that pronounced:

The research team found that in current smokers who were also heavy drinkers, cognitive decline was 36% faster than in non-smoking moderate drinkers. This was equivalent to an age effect of 12 years – an additional two years over the 10-year follow up period. 

Is it that easy to tell the difference between, say, a 67 year old brain and a 65 year old one?