Research suggests that smoking does increase the risk of developing Alzheimer disease and other types of dementia.

Large studies have looked at this question. Researchers have analyzed the medical records of thousands of patients. They have asked about health habits, including smoking. And they have reviewed measures such as blood pressure, cholesterol levels, and weight. Finally, they have looked at trends over many decades in these individuals.

What does this research suggest?

People who smoke more than two packs of cigarettes a day at midlife double their risk of developing dementia in old age when compared with nonsmokers.

People who stop smoking by midlife and those who smoke less than half a pack a day have a risk of dementia similar to that of people who had never smoked.

So we do know that smoking is a risk factor for dementia. But we don’t know exactly how tobacco use hurts the brain.  

The cause may be indirect. Smoking causes heart disease. And heart disease increases the risk of dementia.  

Smoking also can cause blood clots. When blood clots break off, they can travel to blood vessels in the brain. That blocks oxygen flow. Midlife smoking can thus cause small or large strokes.  

Apart from stroke, cigarette smoking also increases the risk of “vascular dementia.” This is when there is decreased blood flow to the brain. This is the second most common form of dementia.  

Tobacco is the leading cause of preventable death in the United States. It accounts for about one of every five American deaths. The risk of dementia is an additional reason to quit smoking.

Most people need help to quit. Options are counseling, nicotine replacement therapy and medicine. Most smokers also try to quit multiple times before succeeding.

Focus on the health benefits. You’ll breathe better. You’ll cut your risk of heart disease. You will probably protect your brain. These are all prescriptions for a better quality of life.

It’s difficult, but worth the effort.