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Fact Sheet

Smoking and Dementia

Nov 2021
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This fact sheet examines the links between smoking and dementia. 14.4% of adults in England are current smokers, and smoking contributes to almost 78,000 deaths every year.1

Smoking is associated with an increased risk of dementia.2 A 2017 Lancet Commission on dementia risk ranked smoking third among 9 modifiable risk factors for dementia.3 The WHO estimates that 14% of cases of Alzheimer’s disease worldwide are potentially attributable to smoking.4

Globally, there are an estimated 50 million people living with dementia. Dementia is an umbrella term a for a range of progressive neurodegenerative conditions which are characterised by symptoms such as memory loss, difficulties with thinking, problem-solving or language (cognitive function). The most common causes of dementia are Alzheimer’s disease, vascular dementia, frontotemporal dementia and dementia with Lewy bodies.5

It can be caused by a combination of different types which is sometimes referred to as mixed dementia.6 In all types of dementia, brain cells degenerate and die at a faster rate compared to the normal ageing process.7 8

Dementia predominantly occurs in older people and is a consequence of complex interactions between genetic, environmental and lifestyle factors.9 Late-onset dementia (in people aged over 65) is the most common form, accounting for over 90% of cases.10 The two main types of dementia are Alzheimer’s disease and vascular dementia.11

Alzheimer’s, the most common cause of dementia, is a physical disease where the brain progressively becomes more damaged leading to a gradual worsening of symptoms. Life expectancy following diagnosis is typically three to eleven years.12

The cause of Alzheimer’s disease is poorly understood, but the disease is characterised by the build-up of plaques (structures of amyloid proteins) and tangles (made up of tau filaments) in the brain.13 This leads to a loss of connections between nerve cells and eventually to the death of nerve cells and loss of brain tissue.14

Genetic studies have found that there are more than 20 genes associated with susceptibility to Alzheimer’s disease.15 Genetic risk factors will likely interact with modifiable environmental risk factors to further increase the risk of developing Alzheimer’s disease.16 It is possible more genetic risk factors for Alzheimer’s disease and other manifestations of dementia will be discovered.

Vascular dementia is dementia caused by problems in the supply of blood to the brain. There are many overlapping symptoms of Alzheimer’s disease and Vascular dementia meaning that diagnosis can be challenging.17 About 20% of people who have a stroke develop post-stroke dementia within the following six months.18

The link between smoking and dementia

Smoking is associated with an increased risk of dementia.2 A 2017 Lancet Commission on dementia risk ranked smoking third among 9 modifiable risk factors for dementia.3

A meta-analysis of studies undertaken in the 1990s and early 2000s found that relative to never smokers, current smokers had a risk ratio of 1.79 for Alzheimer’s disease and 1.78 for vascular dementia.19 Another systematic review found slightly lower odds, with risks of 1.59 for Alzheimer’s and 1.35 for vascular dementia.20 A more recent review of 37 studies found that compared to never smokers, current smokers had an increased risk of all-cause dementia of 1.30, and a risk ratio of 1.40 for Alzheimer’s disease.21

A large Finnish study found that people who smoke heavily (more than two packs a day) in their midlife years more than double their risk of developing Alzheimer’s disease or other forms of dementia two decades later. This suggests that there is a possible dose-response relationship – i.e. the more someone smokes, the higher their risk of developing dementia.22 Similar results were recorded in the Honolulu-Asia Aging study (odds ratio for Alzheimer’s disease of 2.18 for medium and 2.40 for heavy smoking levels).23 A Chinese study also found that, compared to low consumption smokers, the adjusted risk of Alzheimer’s disease was significantly increased among medium to high consumption smokers.24

The WHO estimates that 14% of cases of Alzheimer’s disease worldwide are potentially attributable to smoking.4

This evidence contradicts the findings of some studies conducted in the early 1990s which had suggested that smoking had a protective effect against dementia, particularly Alzheimer’s disease.25 It was hypothesised that nicotine from cigarettes could compensate for the loss of nicotinic receptors in the brain associated with Alzheimer’s disease. This theory was perpetuated by the tobacco industry which influenced a number of studies examining smoking and mental health disorders.26 27 This theory has now been discredited.

Selection bias may affect the outcome of some studies since a higher proportion of smokers die prematurely.28 Therefore, it is possible that the association between smoking as a risk factor for dementia has been obscured.29

In terms of mechanistic links between smoking and dementia, our current understanding is limited. Nevertheless, chronic exposure to cigarette smoke has been linked to oxidative stress which is connected to the onset of dementia. Smoking also increases the risk of developing risk factors for Alzheimer’s disease such as stroke and hypertension.6

Secondhand smoke and dementia

There has been evidence of an association between secondhand smoke (SHS) and dementia.30 31 A review of three cross-sectional studies showed a significant association between SHS and cognitive impairment in older adults with a relative risk of 1.30 - 1.90.32 Other studies suggest that there may be a dose-response risk with those exposed to tobacco smoke over many years at increased risk of dementia.33 34 35 36

Smoking, dementia and other modifiable risk factors

People who adopt a healthy lifestyle are less likely to develop dementia. Not smoking, exercising regularly, maintaining a healthy weight, eating a balanced diet and drinking alcohol within NHS lower-risk guidelines all help minimise the risk of dementia, as well as reducing the risk of cancer, circulatory disease and other mental health disorders.37 38 As there is no cure for dementia it is essential to identify and raise awareness of these modifiable risk factors in order to reduce the burden of the disease on society. Using computer modelling, an Australian study estimated that for each 5% fall in smoking prevalence there would be a 2% reduction in dementia risk.39

The ageing population and dementia rates

Globally, there are an estimated 50 million people living with dementia, a number predicted to triple by 2050.40 In the UK, about 850,000 people have the condition. The Alzheimer’s Society forecasts that this will rise to over one million people by 2021 and over two million by 2051 if no action is taken and current trends continue.41

The rise in dementia is largely due to an ageing population; advanced age is the biggest single risk factor for dementia. As a 2015 editorial in The Lancet noted: “The ageing of populations is poised to become the next global health challenge. During the next 5 years, for the first time in history, people aged 65 years and older in the world will outnumber children aged younger than 5 years.” 42 After the age of 65, a person’s risk of developing Alzheimer’s disease doubles approximately every 5 years. One in six people over the age of 80 have dementia.43 However, dementia is not an inevitable part of ageing.

Benefits of smoking cessation

Stopping smoking at any age is beneficial and the younger a person quits, the greater the benefits in terms of life expectancy gained. Long-term smokers lose on average 10 years of life, compared to those who have never smoked.44 A longitudinal study of British doctors spanning 50 years showed that people who stop smoking at age 60, 50, 40, or 30 gain, respectively, about 3, 6, 9, or 10 years of life expectancy.44 In another study, both long term quitters and never smokers were found to have a decreased risk of Alzheimer’s disease and vascular dementia compared to smokers.45

A Whitehall cohort study found that, compared with never smokers, middle-aged male smokers experienced faster cognitive decline. However, among former smokers who had refrained from smoking for at least 10 years, there were no adverse effects on cognitive decline.46

Stopping smoking in middle age and keeping other risk factors under control will reduce the risk of dementia. There are also immediate health benefits such as reduced blood pressure and improved lung function even after a person has been diagnosed with the disease.

People with early stages of dementia who smoke and are reluctant to quit, or find stopping difficult, may benefit from using electronic cigarettes to reduce the harm from smoking. Leading UK health and public health organisations including the RCGP, BMA and Cancer Research UK now agree that e-cigarettes are far less harmful than smoking. Based on an assessment of the available international peer-reviewed evidence, Public Health England and the Royal College of Physicians estimate the risk reduction to be at least 95%.47

Reduced fire risk

People with dementia who smoke have an increased risk of fire at home as they are less likely to follow safe smoking procedures, such as extinguishing cigarettes fully and disposing of them correctly.48 In order to reduce the risk of fire, it is clearly advantageous to help people with dementia to stop smoking as soon as possible. They may be assisted by the adoption of smokefree policies in residential care homes. Although bedrooms and designated smoking rooms in care homes are exempt from the smokefree workplace law, the providers of sheltered accommodation may choose to make the whole premises smokefree.49 Provided that this policy is communicated to residents and their relatives, as well as being properly enforced, going smokefree can lead to a safer, more pleasant environment for both staff, residents and visitors.

Further information and resources

For details of local Stop Smoking Services see:
Alzheimer’s Society:
National Dementia Helpline: 0300 222 11 22
ASH Fact sheet: Smoking and mental health

Smoking and mental health. A joint report by the Royal College of Physicians and the Royal College of Psychiatrists. London, RCP, 2013.

  • [1]

    Statistics on Smoking - England, 2019, NHS England

  • [2]

    Choi D, Choi S, Park SM. Effect of smoking cessation on the risk of dementia: a longitudinal study. Annals of Clinical and Translational Neurology. 2018.

  • [3]

    Livingston G, Sommerlad A, Orgeta V, Costafreda SG, Huntley J, Ames D, Ballard C, Banerjee S, Burns A, Cohen-Mansfield J, Cooper C. Dementia prevention, intervention, and care. The Lancet. 2017 Dec 16;390(10113):2673-734

  • [4]

    McKenzie J, Bhatti L, Tursan d’Espaignet E. WHO Tobacco Knowledge Summaries: Tobacco and dementia. WHO, 2014

  • [5]

    Ljubenkov PA, Geschwind MD. Dementia. Semin Neurol. 2016. 36(4):397-404.

  • [6]

    Custodio, N et al. Mixed dementia: A review of the evidence. Dement Neuropsychologia. 2017. 11(4): 364–370.

  • [7]

    Wang J, Gu BJ, Masters CL, Wang YJ. A systemic view of Alzheimer disease - insights from amyloid-β metabolism beyond the brain. Nat Rev Neurol. 2017;13(11):703

  • [8]

    Alzheimer’s Society. What is Alzheimer’s disease?

  • [9]

    McKenzie J, Bhatti L, Tursan d’Espaignet E. Tobacco use knowledge summaries: Tobacco use & dementia. WHO, 2014.

  • [10]

    Durazzo TC, Mattsson N, Weiner MW. Smoking and increased Alzheimer’s risk: A review of potential mechanisms. Alzheimer’s & Dementia. 2014; 10(3): S122-S145.

  • [11]

    Sacuiu SF. Dementias. Handb Clin Neurol 2016. 138:123-51.

  • [12]

    Todd S, Barr S, Roberts M, Passmore AP. Survival in dementia and predictors of mortality: a review. International journal of geriatric psy, 2013

  • [13]

    Lane CA, Hardy J, Schott JM. Alzheimer’s Disease. Eur J Neurol. 2018 25(1):59-70.

  • [14]

    Crews L, Masliah E. Molecular mechanisms of neurodegeneration in Alzheimer’s disease. Human molecular genetics. 2010 Apr 15;19(R1):R12-20.

  • [15]

    Huang X, Liu H, Li X, Guan L, Li J, Tellier LCAM, et al. Revealing Alzheimer’s disease genes spectrum in the whole-genome by machine learning. BMC Neurol. 2018;18(1):5.

  • [16]

    Karch CM, Goate AM. Alzheimer’s disease risk genes and mechanisms of disease pathogenesis. Biological psychiatry. 2015 Jan 1;77(1):43-51.

  • [17]

    T O’Brien J, Thomas A. Vascular dementia. The Lancet. 2015 Oct 24;386(10004):1698-706.

  • [18]
  • [19]

    Anstey KJ, von Sanden C, Salim A, O’kearney R. Smoking as a risk factor for dementia and cognitive decline: a meta-analysis of prospective studies. American journal of epidemiology. 2007 Jun 14;166(4):367-78.

  • [20]

    Peters R, Poulter R, Warner J, Beckett N, Burch L, Bulpitt C. Smoking, dementia and cognitive decline in the elderly, a systematic review. BMC geriatrics. 2008 Dec;8(1):36.

  • [21]

    Zhong G, Wang Y, Zhang Y, Guo JJ, Zhao Y. Smoking is associated with an increased risk of dementia: a meta-analysis of prospective cohort
    studies with investigation of potential effect modifiers
    . PloS one. 2015 12;10(3):e0118333.

  • [22]

    Rusanen M, Kivipelto M, Quesenberry CP, Zhou J, Whitmer RA. Heavy smoking in midlife and long-term risk of Alzheimer disease and vascular
    . Archives of internal medicine. 2011 Feb 28;171(4):333-9.

  • [23]

    Tyas SL, White LR, Petrovitch H, Ross GW, Foley DJ, Heimovitz HK, Launer LJ. Mid-life smoking and late-life dementia: the Honolulu-Asia Aging
    . Neurobiology of aging. 2003 1;24(4):589-96.

  • [24]

    Juan DD, Zhou DH, Li J, Wang JY, Gao C, Chen M. A 2-year follow-up study of cigarette smoking and risk of dementia. European Journal of Neurology. 2004 Apr;11(4):277-82.

  • [25]

    Van Duijn CM, Havekes LM, Van Broeckhoven C, De Knijff P, Hofman A. Apolipoprotein E genotype and association between smoking and early onset Alzheimer’s disease. BMJ. 1995 Mar 11;310(6980):627-31.

  • [26]

    US Department of Health and Human Services. The health consequences of smoking—50 years of progress: a report of the Surgeon General. US Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health. 2014 Nov 27;17.

  • [27]

    Cataldo JK, Prochaska JJ, Glantz SA. Cigarette smoking is a risk factor for Alzheimer’s Disease: an analysis controlling for tobacco industry affiliation. Journal of Alzheimer’s disease. 2010 1;19(2):465-80.

  • [28]

    Hernán MA, Alonso A, Logroscino G. Commentary: Cigarette Smoking and Dementia: Potential Selection Bias in the Elderly. Epidemiology. 2008
    May 1:448-50.

  • [29]

    Durazzo TC, Mattsson N, Weiner MW, Alzheimer’s Disease Neuroimaging Initiative: Smoking and increased Alzheimer’s disease risk: a review
    of potential mechanisms
    . Alzheimers Dement. 2014 10(3 0): S122–S145.

  • [30]

    Killin L. O. J., Starr J. M., Shiue I. J. and Russ T. C. Environmental risk factors for dementia: a systematic review. BMC Geriatrics, 2016. 16, 175.

  • [31]

    Stirland LE, O’Shea Cl, Russ TC. Passive smoking as a risk factor for dementia and cognitive impairment: systematic review of observational studies. Int Psychogeriatr. 2018 30(8):1177-1187.

  • [32]

    Chen R, Hu Z, Orton S, Chen RL, Wei L. Association of passive smoking with cognitive impairment in nonsmoking older adults: a systematic literature review and a new study of Chinese cohort. Journal of Geriatric Psychiatry and Neurology. 2013 Dec;26(4):199-208.

  • [33]

    Barnes DE, Haight TJ, Mehta KM, Carlson MC, Kuller LH, Tager IB. Secondhand smoke, vascular disease, and dementia incidence: findings from the cardiovascular health cognition study. American journal of epidemiology. 2010 Jan 5;171(3):292-302.

  • [34]

    Llewellyn DJ, Lang IA, Langa KM, Naughton F, Matthews FE. Exposure to secondhand smoke and cognitive impairment in non-smokers: national
    cross sectional study with cotinine measurement
    . BMJ. 2009 Feb 12;338:b462.

  • [35]

    Barrett JR. Neurology: Dementia and secondhand smoke. Environmental Health Perspectives 2007; 115(8):A401

  • [36]

    Chen R, Hu Z, Zhang D, Ma Y, Wei L. Second-hand smoke and dementia. Epidemiology. 2013 1;24(4):623-4.

  • [37]

    Alzheimer’s Society. How to reduce your risk of dementia.

  • [38]

    Livingston G, Sommerlad A, Orgeta V, Costafreda SG, Huntley J, Ames D, Ballard C, Banerjee S, Burns A, Cohen-Mansfield J, Cooper C. Dementia prevention, intervention, and care. The Lancet. 2017 16;390(10113):2673-734

  • [39]

    Nepal B, Brown L, Ranmuthugala G. Modelling the impact of modifying lifestyle risk factors on dementia prevalence in Australian population aged 45 years and over, 2006–2051. Australasian journal on ageing. 2010 Sep;29(3):111-6.

  • [40]
  • [41]
  • [42]

    Suzman R, Beard J, Boerma T & Chatterji S. Health in an ageing world - what do we know? The Lancet. 2015 Feb 7;385(9967):484-6.

  • [43]

    Dementia Statistics Hub. Prevalence by age in the UK.

  • [44]

    Doll R, Peto R, Boreham J, Sutherland I. Mortality in relation to smoking: 50 years’ observations on male British doctors. Bmj. 2004 Jun 24;328(7455):1519.

  • [45]

    Choi D, Choi S, Park SM. Effect of smoking cessation on the risk of dementia: a longitudinal study. Annals of Clinical and Translational Neurology. 2018.

  • [46]

    Sabia S, Elbaz A, Dugravot A, Head J, Shipley M, Hagger-Johnson G, Kivimaki M, Singh-Manoux A. Impact of smoking on cognitive decline in early old age: the Whitehall II cohort study. Archives of general psychiatry. 2012 1;69(6):627-35.

  • [47]

    McNeill A, Brose LS, Calder R, Bauld L, Robson D. Evidence review of e-cigarettes and heated tobacco products. Public Health England, 2018.

  • [48]

    Alzheimer’s Society. Smoking and alcohol with dementia.

  • [49]