How smoking cigarettes is linked to the development of dementia

July 14, 2025
  • Ahkhash Shanker

Intro:

It is widely known that smoking cigarettes is a deadly recreational activity. Smoking has significant impacts on cardiovascular and respiratory health. It is also highly addictive in nature and increases the risk of developing cancer. These risks have been emphasized by health agencies for decades. However, the harms of smoking extend beyond just these well-known impacts – smoking’s tendrils of destruction can extend even into our brains, damaging cognitive function and memory. This may lead us to wonder – does smoking cause dementia or Alzheimer’s disease?

Dementia is a set of disorders that have significant functional impact and involve deterioration of one’s cognitive function, memory and ability to organize thoughts. Dementia can develop and arise through a variety of mechanisms, but evidence shows that smoking cigarettes can induce and speed up the development of dementia 1. In this article we will explore the impacts smoking can have on one’s cognitive function and how quitting smoking is an effective way to significantly reduce the risk of developing dementia.

This article will focus primarily on the impact of smoking cigarettes on one’s risk for dementia and Alzherimer’s disease, not if vaping or smoking marijuana causes dementia.

Background regarding Types of dementia:

Before we can explore links between smoking and dementia, we must first briefly review three types of dementia that are commonly linked to smoking. The three types of dementia we will explore are Alzheimer’s disease, vascular dementia and Lewy body dementia.

Alzheimer’s disease 

Alzheimer’s disease involves gradual progressive cognitive decline with clear functional impact 2. The pathology of this disease involves the presence of  amyloid plaques and neurofibrillary tangles within the brain. These clumps disrupt synaptic connections between neurons and consequently affect cognitive function. Amyloid plaques are made of amyloid-beta (Aβ) and Neurofibrillary tangles consist of phosphorylated Tau proteins. The effect of these disruptions to neuronal communication results in worsened cognitive function, especially memory. 

Vascular dementia 

Vascular dementia refers to cognitive impairment with functional impact that occurs  when the brain receives less blood than is adequate2. This can be linked to various cardiovascular disorders that may be preventing blood from reaching the brain, such as strokes or atherosclerosis. The effect of less blood reaching the brain is impaired memory, decision-making, planning and reasoning. Whereas the impact of Alzheimer’s disease is often primarily on one’s short term memory, vascular dementia is more impactful on several other cognitive functions which can include decision-making capabilities and problem-solving speed. Individuals with vascular dementia can find it hard to pay attention, organize thoughts, think critically and remember information, and can even face depression. It can have either a slow and gradual, or fast onset (such as shortly after a stroke). 

Lewy body dementia

Lewy body dementia is similar to Alzheimer’s disease in the sense that formations of protein interfere with communication between cells in the brain 2. However, instead of these formations being made of Amyloid Beta or phosphorylated Tau proteins, they are instead made of protein clumps called Lewy bodies. Lewy body dementia disrupts sleep, one’s ability to think clearly and can cause hallucinations. 

To learn more about these types of dementia as well as other types of dementia such as Frontotemporal dementia, mixed dementia and Creutzfeldt-Jakob disease, feel free to explore this article by DeterDementia.

Is smoking a risk factor for dementia? How important is quitting?

A vast amount of studies have been conducted that have found that smoking significantly contributes to and speeds up the development of dementia. Two studies outlined in the 2014 World Alzheimer Report found a positive correlation between the amount of tobacco smoked and one’s risk for dementia 1. This increase in dementia risk is true for both Vascular dementia and Alzheimer’s. The World Health Organization estimates that smoking is responsible for approximately 14% of all Alzheimer’s disease cases 3. One study found that smoking increases one’s risk factor from 1 to 1.79 for Alzheimer’s, to 1.78 for vascular dementia and 1.27 for dementia in general 4. Another study found that globally, smoking is the 2nd highest contributor to Alzheimer’s cases, second only to a lack of education 5.

The damaging effects of smoking occur at any age. Younger smokers such as teenagers and young adults have still-developing brains, and smoking can cause long-term health effects including dementia 6. Middle-age and older smokers are not safe from these dangerous effects either. A 2015 analysis of 37 studies found that current smokers are 30% more likely to develop dementia and 40% more likely to develop Alzheimer’s than non-smokers, and that their risk for dementia development increases by 34% for every extra 20 cigarettes smoked per day 3. Smoking is an additive risk factor, and can combine with other factors such as alcohol consumption and lack of exercise resulting in greater overall dementia risk 7. A Finnish study found that smoking over 2 packs a day can double one’s risk for dementia 20 years in the future 8. Studies in both low and high-income countries have shown that smoking is a risk factor for dementia 9. 

What about patients who already have dementia?

Even for patients who already have dementia, smoking can be risky. Dementia disrupts one’s memory and cognitive functions, and this can interfere with being able to complete normal tasks. This can pose a risk for smokers as smoking requires proper safety procedures 8. Individuals with dementia are less likely to remember to extinguish cigarettes and safely dispose of them after use. Failure to remember these procedures increases the risk of fires, posing a danger to smokers and those around them. This is especially true for smokers with dementia who live alone. Residence homes for the elderly should implement anti-smoking help programs to prevent fires.

The effects of second-hand smoke:

Even if one does not smoke, exposure to second-hand smoke can also increase their risk for developing dementia. The more exposure one has to second-hand smoke, the higher this risk 9. This has been explored and shown in many studies, including one which showed that exposure to second-hand smoke caused memory loss in women aged 55-64 10.

What if I already smoke?

Even if one already smokes, quitting this habit can have huge benefits and significantly lower one’s chance of developing dementia. In fact, quitting smoking for a long-enough period of time can lower one’s chance of dementia to that of someone who has never smoked, especially for those under the age of 65 11. Smoking causes the loss of gray matter, which makes up part of the brain and allows for senses, perception, emotions, speech, learning, cognition and movement 6. Quitting smoking stops further loss of gray matter, but the brain cannot return to its original size or regain the lost gray matter. Therefore, stopping as early as possible is imperative. Dementia risk continuously decreases the longer one spends away from cigarettes 11. Professor Jennifer Deal led a study and found that it can take 9 years for a smoker who quits to reach similar dementia-risk levels as a non-smoker. Another study found that men above 60 who smoked for over 4 years had substantially lower dementia risk after quitting than those who didn’t quit 10. 

Therefore, if you are a heavy smoker and are worried about developing dementia, fear not. All hope is not lost; quitting this habit can help undo the damage that has been done and significantly lower your risk of developing dementia. You can consult your doctor to learn about effective ways to overcome the habit of smoking.

How smoking can increase risk for types of dementia:

Many studies have found that smoking can significantly increase one’s risk rate for different types of dementia. While the biological mechanisms of how smoking can cause dementia are still being investigated, some possible mechanisms are as follows:

How smoking indirectly causes dementia via cardiovascular disease:

It is well-known that smoking can cause cardiovascular disease. Many of these diseases can impede blood flow to the brain, resulting in the development of vascular dementia 12. Smoking damages blood vessels and stimulates thrombosis (clot formation), which can restrict the flow of blood 11. It also lowers the levels of oxygen present in one’s blood 13. Smoking can cause the development of strokes and atherosclerosis (the narrowing of one’s blood vessels due to plaque deposition) 11. Oxygen is extremely important for the brain to function well, and when the brain is deprived of oxygen cognitive function can be severely impaired and vascular dementia can develop 13.

Not only does atherosclerosis caused by smoking increase one’s risk of vascular dementia, but it can also lead to Alzheimer’s 11. Atherosclerosis caused by smoking restricts blood flow to the brain and this can lead to increased production of Amyloid-beta and increased formation of amyloid plaques, leading to Alzheimer’s 14.

How smoking directly causes dementia:

Smoking also directly increases one’s risk for forms of dementia. Toxins and chemicals in cigarettes can damage and inflame cells, which can lead to the development of Alzeihmer’s 1. Research on smoking and Alzheimer’s shows that smoking can reduce the brain’s ability to clear out amyloid plaques 14. The presence of more amyloid plaques results in greater disruption of neuronal signalling and a greater chance of Alzheimer’s disease. 

Smoking can also directly cause changes and damage in synaptic signalling pathways, and can even cause one’s brain to shrink 6. When one’s brain shrinks neurons and synaptic connections can be lost, and communication can be impaired further. Areas important for cognitive function such as the hippocampus can shrink. The brain is composed of both white and gray matter, the latter being responsible for senses, perception, learning, speech, cognition, movement and emotion. Smoking unfortunately causes one to lose this critical gray matter. All of these factors lead to dementia and other neurodegenerative diseases. The shrinking of one’s brain is a natural process as one ages, but smoking can greatly speed up this process.

The APOE ε4 gene is a genetic factor which is highly associated with risk for dementia 9. Smoking tobacco significantly increases the risk of dementia for those with this unfortunate gene. Cigarette smoke may potentially cause brain microbleeds and increase the amino acid homocysteine in one’s blood plasma, which is a risk factor for both cardiovascular diseases and dementia. It may also shorten one’s telomeres which can speed up aging and conditions associated with aging including dementia 15. Smoking can also cause oxidative stress which damages cells. This is primarily caused by the component in cigarettes called tobacco. 

Oxidative stress is when there is an imbalance between toxins in one’s cells and antioxidants that remove these toxins 13. When toxins and antioxidants are out of balance the excessive toxins can damage one’s cells. Oxidative stress also increases excitotoxicity (when excessive excitatory neurotransmitters cause neuron death) and inflammation of neuron cells which damages them further 9. It also stimulates the phosphorylation of Tau proteins and aggregation of amyloid-β, forming Amyloid plaques and Neurofibrillary tangles 11. Oxidative stress lowers neuroprotection and causes endothelium cells to fail. All of these factors result in a significant increase in one’s chance to experience dementia.

The effects of nicotine on dementia risk:

Although the link between smoking and dementia is evident and very strong, links between nicotine and dementia risk are more complex. Some findings suggest that the compound in cigarettes known as nicotine may actually help prevent Alzheimer’s disease. 

Some studies have found that nicotine may have anti-amyloidogenic properties, preventing the formation of amyloid plaques 14. It has also been suggested that nicotine can protect brain cells from excitotoxic and ischaemic (lack of blood-flow) damage. This may help prevent Lewy body dementia. 

A patient with Alzheimer’s disease often has lower activity in their nicotinic acetylcholine receptors 16. Nicotine activates these receptors, so this opens a possibility that nicotine might help counter the effects of Alzheimer’s disease, improving cognition and memory. When nicotine binds to nicotinic acetylcholine receptors, it stimulates the release of messengers like acetylcholine, serotonin and dopamine which can act at the prefrontal cortex and hippocampus to increase cognitive activity 17.

This has led researchers to ask: does nicotine prevent dementia, or at least mitigate some of its effects? A literature review in 2021 suggested that nicotine may maintain one’s cognitive abilities as they age, preventing Alzheimer’s at an old age 17. Another trial found that nicotine seemed to improve attention, episodic memory, and cognitive functioning with minimal side effects, but this trial was limited to a period of just 6 months. As of right now research regarding nicotine’s effects on dementia are inconclusive, with mixed results 16. More studies, such as the ongoing Memory Improvement through Nicotine Dosing (MIND) study, are underway, to clear the fog regarding links between nicotine and Alzheimer’s.

Should I use nicotine for dementia prevention?

Although these findings may seem promising, there are a few things to note before resorting to nicotine for dementia prevention. Firstly, when smoking, the negative health effects of tobacco and the many other chemicals outweigh any potential benefits of nicotine, and the overall effect is a significant increase in one’s chance of developing dementia. Therefore, smoking cigarettes is not an effective way to prevent this disease, and will only worsen it. One may be tempted to use a nicotine patch for dementia prevention, but the research in this area is still young and scarce. The relationship between nicotine and dementia is still unclear and needs more long-term research data. Finally, the negative health effects of nicotine may outweigh any potential benefits they may have towards preventing dementia. Nicotine can cause sleepiness, dizziness, digestive conditions and addiction 16. This is a complex area and you should discuss this with your physician or healthcare provider. At this time, there is not sufficient evidence to recommend using nicotine for dementia prevention.

Conclusion:

In conclusion, an increased risk of dementia is one of the many but lesser-known negative impacts of smoking. First or secondhand smoke can drastically increase one’s risk of vascular dementia or Alzheimer’s through many ways. This can be directly, such as by damaging and inflaming cells, or indirectly, such as by causing cardiovascular disorders that can deprive the brain of oxygen and cause vascular dementia. Smoking can even pose risks for patients who already have dementia, as their condition may inhibit them from following safe smoking procedures and smoking can also accelerate their cognitive decline. As a result, quitting smoking as soon as possible is important to lower one’s chance of developing dementia and many other conditions. New research is exploring possibilities such as nicotine potentially playing a role to help  prevent dementia but research regarding this remains inconclusive at this time. Instead, making efforts to quit smoking and consulting your doctor about ways to avoid other risk factors is the best course of action. 

Sources – for reference or for further learning:

  1. Alzheimer’s Society. “Smoking and the risk of dementia.” Alzheimer’s Society, August 2024, https://www.alzheimers.org.uk/about-dementia/managing-the-risk-of-dementia/reduce-your-risk-of-dementia/smoking. Accessed 22 May 2025.
  2. Naqvi, Raza. “Dementia: Symptoms,Types, Risk Factors and Cure.” Deter Dementia, 15 May 2024, https://deterdementia.com/dementia-symptomstypes-risk-factors-and-cure/. Accessed 22 May 2025.
  3. Williamson, Laura. “Smoking harms the brain, raises dementia risk – but not if you quit.” American Heart Association, 6 July 2021, https://www.heart.org/en/news/2021/07/06/smoking-harms-the-brain-raises-dementia-risk-but-not-if-you-quit. Accessed 22 May 2025.
  4. Peters, Ruth, et al. “Smoking, Dementia and Cognitive Decline in the Elderly, a Systematic Review.” BMC Geriatrics, vol. 8, no. 1, 23 Dec. 2008, doi:10.1186/1471-2318-8-36. 
  5. Barnes, Deborah E, and Kristine Yaffe. “The Projected Effect of Risk Factor Reduction on Alzheimer’s Disease Prevalence.” The Lancet Neurology, vol. 10, no. 9, 19 July 2011, pp. 819–828, doi:10.1016/s1474-4422(11)70072-2. 
  6. Berman, Robby, and Jill Seladi-Schulman. “Smoking causes irreversible brain shrinkage, increasing dementia risk.” Medical News Today, 18 December 2023, https://www.medicalnewstoday.com/articles/smoking-causes-brain-shrinkage-but-quitting-may-prevent-further-loss. Accessed 22 May 2025.
  7. Ellison, James M. “Is Smoking Good or Bad for Dementia Prevention?” BrightFocus Foundation, 10 August 2021, https://www.brightfocus.org/resource/is-smoking-good-or-bad-for-dementia-prevention/. Accessed 22 May 2025.
  8. Action on Smoking and Health. “Smoking and Dementia – ASH.” Action on Smoking and Health – ASH, November 2021, https://ash.org.uk/resources/view/smoking-and-dementia. Accessed 22 May 2025.
  9. McKenzie, J., L. Bhatti, and E. Tursan d’Espaignet. WHO Tobacco Knowledge Summaries: Tobacco and Dementia. World Health Organization, 2014.
  10. Livingston, Gill, et al. “Dementia Prevention, Intervention, and Care: 2020 Report of The Lancet Commission.” The Lancet, vol. 396, no. 10248, 8 Aug. 2020, pp. 413–446, doi:10.1016/s0140-6736(20)30367-6. 
  11. Jeong, Su-Min, et al. “Association of Changes in Smoking Intensity with Risk of Dementia in Korea.” JAMA Network Open, vol. 6, no. 1, 19 Jan. 2023, doi:10.1001/jamanetworkopen.2022.51506. 
  12. Mayo Clinic Staff. “Prevention may be possible-Vascular dementia – Symptoms & causes.” Mayo Clinic, 29 July 2021, https://www.mayoclinic.org/diseases-conditions/vascular-dementia/symptoms-causes/syc-20378793. Accessed 22 May 2025.
  13. Puckering, Katie. “All you need to know about smoking and dementia.” Alzheimer’s Research UK, 13 January 2020, https://www.alzheimersresearchuk.org/news/all-you-need-to-know-about-smoking-and-dementia/. Accessed 22 May 2025.
  14. Wortmann, Marc. “P4‐151: World Alzheimer Report 2014: Dementia and Risk Reduction.” Alzheimer’s & Dementia, vol. 11, no. 7S_Part_18, July 2015, doi:10.1016/j.jalz.2015.06.1858. 
  15. Risk Reduction of Cognitive Decline and Dementia: Who Guidelines. World Health Organization, 2019.
  16. Moawad, Heidi, and Zia Sherrell. “Nicotine and Alzheimer’s disease: What is the link?” Medical News Today, 17 Janurary 2025, https://www.medicalnewstoday.com/articles/nicotine-and-alzheimers. Accessed 22 May 2025.
  17. Moawad, Heidi, and Traci Pedersen. “Nicotine and Alzheimer’s: Understanding Dementia Prevention.” Healthline, 18 September 2023, https://www.healthline.com/health/alzheimers-dementia/nicotine-and-alzheimers. Accessed 22 May 2025.