Several large, long-running studies have found that smoking significantly increases your risk of Alzheimer's, as does high exposure to secondhand smoke. Smoking, both in old age and in adolescence, is also associated with lower IQs and lower cognitive performance. It appears, however, that this is largely recoverable if you give up smoking.

Smoking has a particularly negative effect in conjunction with alcohol (and unfortunately they are often found in tandem). While moderate drinking can in some circumstances have positive effects on the brain, this is probably not the case for those who smoke. Moreover, smoking makes it much harder for the brain to recover from the effects of alcohol abuse and the damage done to the brain by heavy alcohol consumption is likely to be much worse if the individual is a smoker.

There are five healthy behaviors that appear to significantly reduce the risk of dementia,

A 35-year study that monitored the healthy behaviors of 2,235 Welsh men aged 45 to 59 at the beginning of the study has found that those who consistently followed at least four of these five healthy behaviors — regular exercise, no smoking, acceptable BMI, high fruit and vegetable intake, and low/moderate alcohol intake — experienced a 60% reduction in dementia and cognitive decline compared with people who followed none. They also had 70% fewer instances of diabetes, heart disease, and stroke,.

Exercise was the most important of these factors.

Only 5% of the men were living a healthy lifestyle (i.e., following at least 4 of these healthy behaviors). Just under half of the 2235 men were non-smokers (46%), and around a third (35%) had an acceptable BMI. Only 15 men ate their “5+” daily (!!), so the requirement was reduced to only three or more portions of fruit and vegetables, enabling 18% to reach it. 39% exercised regularly and 59% reported alcohol intake within the guidelines. Only two men managed five healthy behaviors, and 109 managed four; 19% managed three; 36% two; 31% one; 8% couldn’t manage any.

Elwood, P., Galante, J., Pickering, J., Palmer, S., Bayer, A., Ben-Shlomo, Y., … Gallacher, J. (2013). Healthy Lifestyles Reduce the Incidence of Chronic Diseases and Dementia: Evidence from the Caerphilly Cohort Study. PLoS ONE, 8(12), e81877. doi:10.1371/journal.pone.0081877

The study involved 74 non-smokers with amnestic MCI (average age 76), of whom half were given a nicotine patch of 15 mg a day for six months and half received a placebo. Cognitive tests were given at the start of the study and again after three and six months.

After 6 months of treatment, the nicotine-treated group showed significant improvement in attention, memory, speed of processing and consistency of processing. For example, the nicotine-treated group regained 46% of normal performance for age on long-term memory, whereas the placebo group worsened by 26%.

Nicotine is an interesting drug, in that, while predominantly harmful, it can have positive effects if the dose is just right, and if the person’s cognitive state is at a particular level (slipping below their normal state, but not too far below). Too much nicotine will make things worse, so it’s important not to self-medicate.

Nicotine has been shown to improve cognitive performance in smokers who have stopped smoking and previous short-term studies with nicotine have shown attention and memory improvement in people with Alzheimer's disease. Nicotine receptors in the brain are reduced in Alzheimer’s brains.

Because the dose is so crucial, and the effects so dependent on brain state (including, one assumes, whether the person has been a smoker or not), more research is needed before this can be used as a treatment.

In the last five years, three studies have linked lower neighborhood socioeconomic status to lower cognitive function in older adults. Neighborhood has also been linked to self-rated health, cardiovascular disease, and mortality. Such links between health and neighborhood may come about through exposure to pollutants or other environmental stressors, access to alcohol and cigarettes, barriers to physical activity, reduced social support, and reduced access to good health and social services.

Data from the large Women’s Health Initiative Memory Study has now been analyzed to assess whether the relationship between neighborhood socioeconomic status can be explained by various risk and protective factors for poor cognitive function.

Results confirmed that higher neighborhood socioeconomic status was associated with higher cognitive function, even after individual factors such as age, ethnicity, income, education, and marital status have been taken into account. A good deal of this was explained by vascular factors (coronary heart disease, diabetes, stroke, hypertension), health behaviors (amount of alcohol consumed, smoking, physical activity), and psychosocial factors (depression, social support). Nevertheless, the association was still (barely) significant after these factors were taken account of, suggesting some other factors may also be involved. Potential factors include cognitive activity, diet, and access to health services.

In contradiction of earlier research, the association appeared to be stronger among younger women. Consistent with other research, the association was stronger for non-White women.

Data from 7,479 older women (65-81) was included in the analysis. Cognitive function was assessed by the Modified MMSE (3MSE). Neighborhood socioeconomic status was assessed on the basis of: percentage of adults over 25 with less than a high school education, percentage of male unemployment, percentage of households below the poverty line, percentage of households receiving public assistance, percentage of female-headed households with children, and median household income. Around 87% of participants were White, 7% Black, 3% Hispanic, and 3% other. Some 92% had graduated high school, and around 70% had at least some college.

[2523] Shih RA, Ghosh-Dastidar B, Margolis KL, Slaughter ME, Jewell A, Bird CE, Eibner C, Denburg NL, Ockene J, Messina CR, et al. Neighborhood Socioeconomic Status and Cognitive Function in Women. Am J Public Health [Internet]. 2011 ;101(9):1721 - 1728. Available from:


Lang IA, Llewellyn DJ, Langa KM, Wallace RB, Huppert FA, Melzer D. 2008. Neighborhood deprivation, individual socioeconomic status, and cognitive function in older people: analyses from the English Longitudinal Study of Ageing. J Am Geriatr Soc., 56(2), 191-198.

Sheffield KM, Peek MK. 2009. Neighborhood context and cognitive decline in older Mexican Americans: results from the Hispanic Established Populations for Epidemiologic Studies of the Elderly. Am J Epidemiol., 169(9), 1092-1101.

Wight RG, Aneshensel CS, Miller-Martinez D, et al. 2006. Urban neighborhood context, educational attainment, and cognitive function among older adults. Am J Epidemiol., 163(12), 1071-1078.

Binge drinking is, unfortunately, most common among adolescents (12-20 years). But this is a time when brains are still developing. Does this make them more vulnerable to the detrimental effects of excessive alcohol?

A study involving adolescent mice has revealed that not only did an alcoholic binge reduce the activity of many neurotransmitter genes, but that gene expression in adulthood was even more seriously reduced. Although this deficit didn’t translate into problems with spatial learning, adult mice that had been exposed to excess alcohol in adolescence were significantly worse on a reversal learning task. Moreover, certain brain regions (the olfactory bulb and basal forebrain) were smaller.

In humans, it is thought that these impairments might translate into greater difficulty in adapting to changed situations, in evaluating consequences and controlling impulses.

Similarly, another recent study involving teenagers (15-21) has found that activity in the prefrontal cortex varied according to how heavily they smoked, with those who smoked most heavily having the least activity.

The 25 smokers and 25 non-smokers were tested on a Stop-Signal Task, which tests a person’s ability to inhibit an action. Despite the differences in activity level, smokers and non-smokers performed similarly on the task, suggesting that other brain areas are in some way compensating for the impaired prefrontal cortex. Nevertheless, reduced activity in the prefrontal cortex, which is still developing in adolescence, does suggest long-term consequences for decision-making and cognitive control.

Data from 21,123 people, surveyed between 1978 and 1985 when in their 50s and tracked for dementia from 1994 to 2008, has revealed that those who smoked more than two packs per day in middle age had more than twice the risk of developing dementia, both Alzheimer's and vascular dementia, compared to non-smokers.

A quarter of the participants (25.4%) were diagnosed with dementia during the 23 years follow-up, of whom a little over 20% were diagnosed with Alzheimer's disease and nearly 8% with vascular dementia.

Former smokers, or those who smoked less than half a pack per day, did not appear to be at increased risk. Associations between smoking and dementia did not vary by race or sex.

Smoking is a well-established risk factor for stroke, and is also known to contribute to oxidative stress and inflammation.

Comparison of the brains of 22 smokers and 21 people who have never smoked in their lives has revealed that the left medial orbitofrontal cortex of the smokers was on average smaller than that of the non-smokers. Moreover, this reduction was greater the more cigarettes were smoked daily, and as a function of how long they had smoked. The region is involved in reward, impulse control, and decision-making, suggesting that fewer neurons there may mean you have to work harder for reward, and that your ability to curb your impulses and make decisions is impaired.

While it may be that smoking is affecting this damage, it may also be that those with a smaller orbitofrontal cortex are more likely to smoke (perhaps it is most likely that both are true!). Further research will need to distinguish these two possibilities.

A 12-year study following the drinking and smoking habits of 22,524 people aged 39-79 has found that in non-smokers, people who consumed moderate amounts of alcohol were 37% less likely to develop stroke than non-drinkers. This association was not found among smokers. The finding may explain the inconsistency in previous studies into the relationship between light to moderate drinking and stroke.

The findings were presented at the American Academy of Neurology's 62nd Annual Meeting in Toronto, April 10 - 17, 2010.

Data from more than 20,000 18-year-old Israeli men has revealed that IQ scores are lower in male adolescents who smoke compared to non-smokers, and in twin brothers who smoke compared to their non-smoking brothers. The average IQ for a non-smoker was about 101, while the smokers' average was about 94, with those who smoked more than a pack a day being lower still, at about 90. 28% of the sample smoked one or more cigarettes a day, 3% identified as ex-smokers, and 68% said they never smoked.

Older news items (pre-2010) brought over from the old website

Second-hand smoke linked to cognitive impairment

Smoking is known to be a risk factor for cognitive impairment and dementia. Now a large study of some 4800 non-smoking adults over the age of 50 has revealed that exposure to second-hand smoke (measured by levels of a nicotine by-product in their saliva) is associated with an increased chance of developing cognitive impairment, including dementia.

[641] 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 [Internet]. 2009 ;338(feb12_2):b462 - b462. Available from:

The open-access article is available here.

Midlife smokers may have worse memory than non-smokers

Data from the very large Whitehall II study has found that those who smoked were more likely to be in the lowest 20% for cognitive performance compared with those who had never smoked. Those who reported being ex-smokers at the beginning of the study were 30% less likely than smokers to have poor vocabulary and low verbal frequency scores, showing that recovery is likely if smoking is stopped. The study also found a higher risk of death as well as non-participation in cognitive tests among smokers, suggesting the association between smoking and cognition may have been under-estimated.

[476] Sabia S, Marmot M, Dufouil C, Singh-Manoux A. Smoking History and Cognitive Function in Middle Age From the Whitehall II Study. Arch Intern Med [Internet]. 2008 ;168(11):1165 - 1173. Available from:

Smokers are more likely to develop dementia

A seven-year study of some 7,000 people age 55 and older found that those who were current smokers at the time of the study were 50% more likely to develop dementia than people who had never smoked or past smokers. Smoking did not increase the risk for those with the Alzheimer’s gene apolipoprotein E4. Current smokers without the gene were nearly 70% more likely to develop Alzheimer’s than nonsmokers or past smokers without the gene.

[2381] Reitz C, den Heijer T, van Duijn C, Hofman A, Breteler MMB. Relation between smoking and risk of dementia and Alzheimer disease. Neurology [Internet]. 2007 ;69(10):998 - 1005. Available from:

Secondhand smoke increases risk of dementia

Preliminary findings from the Cardiovascular Health Study indicates that elderly people with high lifetime exposure to secondhand smoke (more than 30 years) were approximately 30% more likely to develop dementia than those with no lifetime secondhand smoke exposure. People with abnormalities of their carotid arteries and high lifetime exposure to secondhand smoke were nearly two-and-a-half times as likely to develop dementia as those with no secondhand smoke exposure and no indications of carotid artery disease.

Haight presented the findings at the American Academy of Neurology’s 59th Annual Meeting in Boston, April 28 – May 5, 2007.

Smoking now found detrimental for Alzheimer’s

Previous animal studies had suggested that nicotine reduces the number of amyloid plaques; a new study, however, has found that chronic nicotine exposure increases neurofibrillary tangles.

[2380] Oddo S, Caccamo A, Green KN, Liang K, Tran L, Chen Y, Leslie FM, LaFerla FM. Chronic nicotine administration exacerbates tau pathology in a transgenic model of Alzheimer's disease. Proceedings of the National Academy of Sciences of the United States of America [Internet]. 2005 ;102(8):3046 - 3051. Available from:

Smoking associated with working memory impairment in adolescents

A study of 41 adolescent daily smokers and 32 nonsmokers has revealed that adolescent smokers had impairments in accuracy of working memory performance. Male adolescents as a group begin smoking at an earlier age than female smokers and were significantly more impaired during tests of selective and divided attention. All of the adolescent smokers also showed further disruption of working memory when they stopped smoking.

[1252] Jacobsen LK, Krystal JH, Mencl EW, Westerveld M, Frost SJ, Pugh KR. Effects of smoking and smoking abstinence on cognition in adolescent tobacco smokers. Biological Psychiatry [Internet]. 2005 ;57(1):56 - 66. Available from:

Smoking is bad for the brain

465 participants in the Scottish Mental Survey (11 year olds tested in 1947), approximately half of whom were smokers, were tested again when they were 64. Smokers performed significantly worse in five different cognitive tests than did both former smokers and those who had never smoked. This drop in cognitive function held when factors such as education, occupation and alcohol consumption were taken into account. A link between impaired lung function and cognitive ageing has long been suspected, though the mechanism is unclear.

[2382] Whalley LJ, Fox HC, Deary IJ, Starr JM. Childhood IQ, smoking, and cognitive change from age 11 to 64 years. Addictive Behaviors [Internet]. 2005 ;30(1):77 - 88. Available from:

Smoking and alcohol

Smoking may counteract benefit of moderate drinking on stroke risk

A 12-year study following the drinking and smoking habits of 22,524 people aged 39-79 has found that in non-smokers, people who consumed moderate amounts of alcohol were 37% less likely to develop stroke than non-drinkers. This association was not found among smokers. The finding may explain the inconsistency in previous studies into the relationship between light to moderate drinking and stroke.

The findings were presented at the American Academy of Neurology's 62nd Annual Meeting in Toronto, April 10 - 17, 2010.

Smoking interferes with recovery from alcohol-related brain damage

Another study has come out with more evidence that smoking makes it a lot harder for the brain to recover from the effects of long-term heavy drinking. The study looked specifically at changes in blood flow in the brain — blood flow is affected by alcohol use disorders. The study found that after 5 weeks of abstinence, alcohol-dependent individuals who didn’t smoke showed significantly improved blood flow, but those who smoked showed essentially no change. Moreover, the number of cigarettes smoked daily was correlated with how poorly the blood was flowing in the frontal lobe.

[1045] Mon A, Durazzo TC, Gazdzinski S, Meyerhoff DJ. The impact of chronic cigarette smoking on recovery from cortical gray matter perfusion deficits in alcohol dependence: longitudinal arterial spin labeling MRI. Alcoholism, Clinical and Experimental Research [Internet]. 2009 ;33(8):1314 - 1321. Available from:

Alzheimer's starts earlier for heavy drinkers, smokers

A study of nearly 1000 people diagnosed with possible or probable Alzheimer’s disease has found that those who were heavy drinkers developed Alzheimer’s 4.8 years earlier than those who were not, while heavy smokers developed the disease 2.3 years sooner than people who were not heavy smokers. Those with the APOE å4 gene developed the disease three years sooner than those without the gene variant. The risk factors are additive — those with all three risk factors developed the disease 8.5 years earlier than those with none of the risk factors.

The research was presented at the American Academy of Neurology Annual Meeting in Chicago, April 12 – April 19.

Nicotine may enhance attention and working memory in recovering alcoholics

New findings show that nicotine patches may enhance cognitive functioning among newly recovering alcoholics with a history of smoking. Nicotine (but not tobacco) has been shown to have a cognitive benefit, particularly on attention processes. The study also found that alcoholics who smoked were more sensitive to the drug dose of nicotine than were community controls who also smoked.

[1006] Nixon SJ, Lawton-Craddock A, Tivis R, Ceballos N. Nicotine's Effects on Attentional Efficiency in Alcoholics. Alcoholism: Clinical and Experimental Research [Internet]. 2007 ;31(12):2083 - 2091. Available from:

Smoking interferes with brain's recovery from alcoholism

In another study indicating smoking worsens the effect of alcoholism on the brain, smoking was found to apparently interfere with the brain's ability to recover from the effects of chronic alcohol abuse.

[2371] Durazzo TC, Gazdzinski S, Rothlind JC, Banys P, Meyerhoff DJ. Brain Metabolite Concentrations and Neurocognition During Short‐term Recovery from Alcohol Dependence: Preliminary Evidence of the Effects of Concurrent Chronic Cigarette Smoking. Alcoholism: Clinical and Experimental Research [Internet]. 2006 ;30(3):539 - 551. Available from:

Long-term smoking associated with dulled thinking and lower IQ

A long-term study involving 172 alcoholic and non-alcoholic men has found that long-term smoking impaired memory and reasoning skills and reduced IQ. The effect was most pronounced among those who had smoked for years. The effects of smoking were found among the non-alcoholics as well as the alcoholics, and among the alcoholics, the cognitive impact of long-term heavy smoking appeared to be greater than the impact of drinking.

[1116] Glass JM, Adams KM, Nigg JT, Wong MM, Puttler LI, Buu A, Jester JM, Fitzgerald HE, Zucker RA. Smoking is associated with neurocognitive deficits in alcoholism. Drug and Alcohol Dependence [Internet]. 2006 ;82(2):119 - 126. Available from:

Smoking seems to increase brain damage in alcoholics

Another study has come out indicating that alcoholics who smoke are at greater risk of brain damage. The imaging study compared brain volume in recovered alcoholics and light drinkers. The study found no difference between smokers and non-smokers among the light drinkers, but among the alcoholics, the more severe the tobacco habit, the more brain volume had been lost.

[1049] Gazdzinski S, Durazzo TC, Studholme C, Song E, Banys P, Meyerhoff DJ. Quantitative Brain MRI in Alcohol Dependence: Preliminary Evidence for Effects of Concurrent Chronic Cigarette Smoking on Regional Brain Volumes. Alcoholism: Clinical and Experimental Research [Internet]. 2005 ;29(8):1484 - 1495. Available from:

Cigarette smoking exacerbates alcohol-induced brain damage

Heavy alcohol consumption is known to cause brain damage. A new imaging study has compared 24, one-week-abstinent alcoholics (14 smokers, 10 nonsmokers) in treatment with 26 light-drinking "controls" (7 smokers, 19 nonsmokers), and found that cigarette smoking can both exacerbate alcohol-induced damage as well as independently cause brain damage. The damage is most prominent in the frontal lobes (important in planning, decision-making, and multi-tasking among other functions). Independent of alcohol consumption, cigarette smoking also had adverse effects on brain regions involved in fine and gross motor functions and balance and coordination. Roughly 80% of alcohol-dependent individuals report smoking regularly.

[2370] Durazzo TC, Gazdzinski S, Banys P, Meyerhoff DJ. Cigarette Smoking Exacerbates Chronic Alcohol‐Induced Brain Damage: A Preliminary Metabolite Imaging Study. Alcoholism: Clinical and Experimental Research [Internet]. 2004 ;28(12):1849 - 1860. Available from:

Benefits of nicotine

Nicotine patch may alleviate 'senior moments'

A small preliminary clinical trial has found that four weeks of nicotine skin patches helped decision-making and attention in people with age-associated memory impairment (the mildest form of cognitive impairment in seniors). Given the health risks of smoking, and health risks associated with nicotine patches, it is too early to recommend the use of nicotine to improve memory, however. Nicotine mimics the brain chemical acetylcholine, a nerve signal that plays a role in learning and memory.

[2383] White HK, Levin ED. Chronic transdermal nicotine patch treatment effects on cognitive performance in age-associated memory impairment. Psychopharmacology [Internet]. 2004 ;171(4):465 - 471. Available from: