Smoking Raises Risk for Dementia, But It’s Never Too Late to Quit

“PNECs can sense whatever’s happening in the lung and give a signal to the brain,” says Abhimanyu Thakur, a research fellow at Harvard Medical School and co-author of the study.

When the researchers exposed PNECs to nicotine, the cells released tiny particles carrying biological messages that triggered symptoms associated with dementia and with a specific type of cell death that has been seen in neurodegenerative diseases, including Alzheimer’s and Parkinson’s. But the research is still early and was conducted on cells and in mice, so researchers do not yet know whether this pathway causes dementia in people.

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Smoking may also somehow affect proteins involved in Alzheimer’s disease. It’s not known whether cigarettes themselves directly cause this change, but heavy smokers have higher levels of total and phosphorylated tau, proteins associated with Alzheimer’s disease, in the fluid surrounding the brain and spinal cord.

Smoking has also been associated with changes in amyloid beta, another protein that accumulates abnormally in Alzheimer’s. Finally, smoking is linked to markers of inflammation and oxidative stress. Ongoing inflammation may contribute to dementia. Oxidative stress is a sign that your body is unable to fend off harmful molecules and. over time, it can damage brain cells and blood vessels and contribute to the development of dementia.

What about weed? And vaping?

Research has linked very heavy cannabis use to increased risk for dementia. In a study reported in JAMA Neurology in 2025 that looked at the medical records of six million adults over the age of 45 with no history of dementia, those who had a cannabis-related ER visit or a hospital stay were 1.5 times more likely to get a dementia diagnosis in the next five years than those who went to the hospital for any other reason. They were nearly four times more likely to develop dementia than their peers in the general population. Other large database studies of cannabis use have not consistently shown that it raises risk for dementia. As for vaping, e-cigarettes haven’t been around long enough for researchers to have volumes of data on their impact like they have for conventional cigarettes. It’s also hard to tell whether vaping in mid- or late-adulthood increases dementia risk since the vast majority of older adult vapers are current or former smokers. That is, if they develop dementia, it would be unclear whether it was the smoking or the vaping that contributed.

It’s never too late to quit

For people with healthy, cognitively normal brains, it’s never too late to quit and reduce your risk for dementia. The Whitehall II study, published in The Lancet Regional Health – Europe in 2022, followed 9,951 adults starting in their mid-40s for 32 years. Those who were current smokers from the start of the 32-year period had a 36 percent increased risk of dementia, while former smokers had no more risk than people who had never smoked.

“Smokers who quit, even if quitting comes late, return to nearly the same dementia risk as people who never smoked,” Blum says. It takes about six years for the risk to approach that level.

In another study published in The Lancet Healthy Longevity in 2025, researchers analyzed 18 years of data on the memory and thinking skills of 9,436 adults ages 40 to 89. Once people quit, over the next six years, their rate of cognitive decline was slower than in people who continued smoking, no matter how old they were when they quit.

You can succeed at quitting

Whether you’ve tried to quit before or just assumed you couldn’t, Blum assures, “however addictive [smoking] is, people can quit and do it all the time.”

Kicking the habit for good requires you to address both components of the addiction: physical dependence on nicotine — that is, your body’s need to keep receiving nicotine in order to avoid withdrawal symptoms — and the habitual behavior of smoking, says Frank Vitale, National Director, Pharmacy Partnership for Tobacco Cessation, based at the University of California San Francisco. Medications help with the nicotine dependence. “They either completely get rid of or substantially reduce the physical urge for more nicotine,” Vitale says. Your doctor can prescribe them.

But medicine is only half of the equation.

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Behavior change — that is, no longer following your morning coffee with a cigarette like you’ve always done — is often harder for people than living without nicotine. You have to change your actions and how you think, Vitale explains.

First, identify the situations that usually cue you to light up and decide in advance what you’ll do instead. If you typically smoke while talking on the phone, try doodling to keep your hands busy. If you smoke while you walk the dog, carry a mug of tea with you instead. If a cigarette is part of your morning routine, try stepping outside with your coffee but leaving the smokes behind.

You also have to change how you respond to the thought, “I want a cigarette.” Most people’s instinct is to try to stop thinking about it. But that just makes you think about it more, Vitale says. Instead, acknowledge that it’s just a thought and that you’re not going to act on it.

Many unsuccessful attempts to quit boil down to trying to quit with sheer willpower alone or not using medications correctly. When you address both nicotine dependence and behavior change, you have better odds of quitting for good.

Quitting may be difficult, but you can do it, Blum says. “I want to empower people to feel that they’re not prisoners to this forever.”

There are resources to help smokers quit.