According to the American Lung Association, smoking is the leading cause of preventable death in the U.S. and causes over 480,000 deaths every year.
Smoking damages the heart, lungs and the vascular system, and causes or worsens numerous diseases and conditions.
The link between smoking and the risk of Alzheimer's disease or dementia has long been controversial, yet, most studies show that the brain is not immune to the long-term consequences of heavy smoking. The impact is likely to become even greater as the population ages and the prevalence of Alzheimer's and dementia continues to rise.
Some earlier studies exploring the risk of dementia among smokers concluded that smoking decreased the likelihood of developing Alzheimer’s disease. However, reviews suggested these studies were biased because of the researchers’ connections to the tobacco industry. The conclusion reasoned that if smoking reduces the risk of dementia in later years, it accomplishes that by shortening life.
According to a World Health Organization’s report “Tobacco and Dementia” in 2014, smoking is a risk factor for dementia and current smokers have a 30% to 75% greater risk for developing dementia when compared to nonsmokers.
Additionally, as mentioned in the same report, secondhand smoke exposure may also increase the risk of dementia by more than 25%. Further, data from a Barnes and Yaffe study posted in The Lancet Neurology in 2011 suggested that 14% of Alzheimer’s disease cases could be attributed to smoking.
Additionally, research compiled at the University of Eastern Finland and Kuopio University Hospital in Finland showed that smoking more than two packs of cigarettes daily from age 50 to 60 doubles the risk of dementia later in later life. For example, 25.4% of the participants in the study were diagnosed with dementia an average of 23 years later. Additionally, of the individuals in that group of over 20,000 who had dementia, 1,136 were diagnosed with Alzheimer's disease and 416 of the participants later developed vascular dementia.
Since smoking is a well-established risk factor for strokes, it also can contribute to the risk of vascular dementia through similar means.
The studies also found that smoking contributes to the oxidative stress and inflammation, two components believed to be significant in the development of Alzheimer's disease, and that smoking affects the development of dementia through vascular and neurodegenerative pathways.
Researchers also probed former smokers to gather data on increased risk of dementia. Findings concluded that former smokers or individuals who smoked less than half a pack per day did not appear to be at an increased risk for developing dementia. Further, associations between dementia and smoking did not vary by race or gender.
Smoking is a modifiable risk factor. Smoking cessation is of potential benefit to brain health and is a risk reducer for developing dementia. Various stop-smoking programs are available through the American Heart Association, the American Lung Association, the American Cancer Society and other local health care entities and community organizations.