Smoking Less Won't Reduce Your Dementia Risk—But Quitting Might

dumping cigarettes into a trash can

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Key Takeaways

  • A recent study found that quitting smoking was associated with a lower risk of developing dementia.
  • But a higher risk of dementia was found in people who reduced their cigarette use, compared to those who kept the same rate of consumption.
  • Researchers suggested that public health messaging should emphasize smoking cessation instead of reduction.

Quitting cigarette smoking at any age regardless of how long you’ve been smoking can offer many health benefits—including reducing the risk of premature death, heart disease, and cancer.

Quitting smoking can also reduce your risk of developing dementia, according to a new study published in Jama Network Open. But researchers found that simply cutting back on cigarettes doesn't yield the same benefits. Instead, it was associated with a higher risk of dementia.

“As far as we know, the association of smoking reduction with dementia has not been examined, although the findings of this study suggest that smoking reduction is not a factor in decreased risk of dementia,”  Junhee Park, MD, a co-author of the study and a researcher at the Sungkyunkwan University School of Medicine in Seoul, South Korea, told Verywell in an email. 

Cigarette Use And Smoking Intensity 

To determine if changes in smoking intensity could affect the risk of dementia, Park and her colleagues analyzed nearly 790,000 adults using data from the National Health Insurance Service database in Korea. 

Over 90% of the participants were men with a long history of smoking, and the average age was 52. The participants took biennial health examinations (in 2009 and 2011) and had a final follow-up in 2018. 

By the 2011 health examination, about 15% of the participants had stopped smoking completely, 22% had reduced their smoking frequency, and 16% increased their cigarette use. 

According to Park, the participants who quit smoking had a decreased risk of developing all dementia (8%), Alzheimer's disease (6%), and vascular dementia (16%), compared to those who continued their smoking habits. 

Surprisingly, people who reduced their daily number of cigarettes by at least 50% or more had a 25% increased risk of dementia, compared to those who sustained their smoking intensity.

“Smoking cessation reduces the risk of dementia compared to continuous smoking,” Park said. “However, just smoking reduction did not help reduce the disease burden of dementia at all.” 

The researchers noted participants who bumped up their smoking use also had a small increase in dementia risk.

The 'Sick Quitter Effect'

According to Park, one explanation for the study finding could be the “sick quitter effect,” which implies that people don’t get sick because they refrained from a certain habit like smoking—rather, they avoided smoking or alcohol because they got sick. In other words, patients don't just get dementia because they cut back on smoking, but more likely because they decided to reduce cigarette use because of the onset of dementia or other medical conditions.  

“A reduction or cessation of cigarette smoking could suggest behavioral changes toward a healthy lifestyle because of their health concerns such as comorbidities,” Park said. “Therefore, the decreased risk of dementia associated with smoking cessation could be underestimated because of the sick quitter phenomenon.” 

Another explanation could be compensatory smoking among people who reduce their cigarette use, according to the study. Feelings of nicotine withdrawal might lead people to inhale deeply when they're smoking to maintain their nicotine levels, which may negate any potential health benefits.

Limitations of the Study  

The study population consisted of only Koreans who were mostly male. In addition, there was no information about dementia risk factors, like education level or the presence of apolipoprotein E (APOE 4), a gene commonly associated with Alzheimer's disease.

The researchers also did not collect information on the use of other products like cigars or e-cigarettes, or exposure to secondhand smoke.

Scott Kaiser, MD, director of geriatric cognitive health for the Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, CA, said another limitation of the study is that the participants self-reported their smoking habits, which raises concerns that their behaviors were reported inaccurately.

Furthermore, dementia can progress for more than a decade. He said the duration of the study might not be sufficient enough to explain the associations between changes in smoking and dementia risk. 

Since the study only had a follow-up period of six years, some cases of dementia may not have been diagnosed during the same period. A longer duration of smoking cessation could possibly reduce the risk of dementia even further, the researchers wrote.

Quit Smoking Entirely 

Despite some of the study’s limitations, Kaiser said people should quit smoking entirely sooner rather than later to lower their risk of dementia.

“Even with the limitations of this study, it still supports a large body of evidence that smoking cessation across a population should be a central part of needed strategies to reduce dementia risk,” Kaiser said. 

Toxins in cigarettes can increase cerebral oxidative stress and inflammation and build up plaques and tangles in the brain, which are associated with Alzheimer’s disease and related dementias.

Despite the study findings, Park said that smoking reduction might still impact other health outcomes, such as lowering the risk of lung cancer. 

What This Means For You

If you're looking to reduce or stop cigarette use, you can seek support from your healthcare provider to learn about nicotine replacements and other effective strategies to change smoking habits.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Smoking and tobacco use: Benefits of quitting.

  2. Jeong SM, Park J, Han K, et al. Association of changes in smoking intensity with risk of dementia in KoreaJAMA Netw Open. 2023;6(1):e2251506. doi:10.1001/jamanetworkopen.2022.51506.

  3. MedlinePlus. APOE gene.

  4. Alzheimer’s Society. Smoking and dementia.

By Alyssa Hui
Alyssa Hui is a St. Louis-based health and science news writer. She was the 2020 recipient of the Midwest Broadcast Journalists Association Jack Shelley Award.