Smoking is just a more subtle way of stabbing yourself - causing damage that will shorten your life. One of the impacts of smoking is degraded blood vessel function, and this has a long-term effect on the brain. It is an example of the way in which the state of general health impacts the rate of neurodegeneration: "Heavy smoking in middle age appears to be associated with more than double the risk for Alzheimer's disease and other forms of dementia two decades later. ... [Researchers] analyzed data from 21,123 members of one health care system who participated in a survey between 1978 and 1985, when they were 50 to 60 years old. Diagnoses of dementia, Alzheimer's disease and vascular dementia were tracked from Jan. 1, 1994 (when participants were an average of 71.6 years old), through July 31, 2008. A total of 5,367 participants (25.4 percent) were diagnosed with dementia during an average of 23 years of follow-up, including 1,136 with Alzheimer's disease and 416 with vascular dementia. Those who smoked more than two packs per day in middle age had an elevated risk of dementia overall and also of each subtype, Alzheimer's disease and vascular dementia, compared with non-smokers. ... Smoking is a well-established risk factor for stroke, and may contribute to the risk of vascular dementia through similar mechanisms." As we non-smokers look at this and shake our heads, it is worth recalling that a sedentary lifestyle can be just as damaging to human life expectancy as smoking. Have you looked at the exercise in your life recently?