Data from 196,383 older adults (60+; mean age 64) in the UK Biobank found that a healthy lifestyle was associated with lower dementia risk regardless of genes.
Both an unhealthy lifestyle and high genetic risk were associated with higher dementia risk.
Brain scans of 9,772 people aged 44 to 79, who were enrolled in the UK Biobank study, have revealed that smoking, high blood pressure, high pulse pressure, diabetes, and high BMI — but not high cholesterol — were all linked to greater brain shrinkage, less grey matter and less healthy white matter.
A large meta-analysis has concluded that having diabetes increases the chance that a person with mild cognitive impairment will progress to dementia by 65%.
There was no consistent evidence that hypertension or cholesterol levels increased the risk of someone with MCI progressing to dementia. Smoking was similarly not associated with increased risk, although the reason for this probably lies in mortality: smokers tend to die before developing dementia.
There are five healthy behaviors that appear to significantly reduce the risk of dementia,
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%.
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.
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.
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.
Llewellyn, D. J., Lang, I. A., Langa, K. M., Naughton, F., & Matthews, F. E. (2009). Exposure to secondhand smoke and cognitive impairment in non-smokers: national cross sectional study with cotinine measurement. BMJ, 338(feb12_2), b462 - b462. Retrieved from http://www.bmj.com/cgi/content/abstract/338/feb12_2/b462
The open-access article is available here.
http://www.eurekalert.org/pub_releases/2009-02/uoc-ssl021209.php
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.
Sabia, S., Marmot, M., Dufouil, C., & Singh-Manoux, A. (2008). Smoking History and Cognitive Function in Middle Age From the Whitehall II Study. Arch Intern Med, 168(11), 1165-1173. Retrieved from http://archinte.ama-assn.org/cgi/content/abstract/168/11/1165
http://www.eurekalert.org/pub_releases/2008-06/jaaj-msm060508.php
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.
Reitz, C., Heijer, den, van Duijn, C., Hofman, A., & Breteler, M. (2007). Relation between smoking and risk of dementia and Alzheimer disease. Neurology, 69(10), 998-1005. Retrieved from http://www.neurology.org/content/69/10/998.abstract
http://www.eurekalert.org/pub_releases/2007-09/aaon-sam082807.php
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.
http://www.eurekalert.org/pub_releases/2007-05/aaon-ssi041007.php
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.
Oddo, S., Caccamo, A., Green, K. N., Liang, K., Tran, L., Chen, Y., … LaFerla, F. M. (2005). 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, 102(8), 3046-3051. Retrieved from http://www.pnas.org/content/102/8/3046.abstract
http://www.eurekalert.org/pub_releases/2005-02/uoc--ctp020805.php
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.
Jacobsen, L. K., Krystal, J. H., Mencl, E., Westerveld, M., Frost, S. J., & Pugh, K. R. (2005). Effects of smoking and smoking abstinence on cognition in adolescent tobacco smokers. Biological Psychiatry, 57(1), 56-66. Retrieved from http://www.sciencedirect.com/science/article/B6T4S-4F1HPHV-D/2/785b6707dd46bd75070418e05dff7a13
http://www.eurekalert.org/pub_releases/2005-02/yu-scc020105.php
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.
Whalley, L. J., Fox, H. C., Deary, I. J., & Starr, J. M. (2005). Childhood IQ, smoking, and cognitive change from age 11 to 64 years. Addictive Behaviors, 30(1), 77-88. Retrieved from http://www.sciencedirect.com/science/article/pii/S0306460304001601
http://www.newscientist.com/news/news.jsp?id=ns99996765
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.
www.physorg.com/news190375547.html
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.
Mon, A., Durazzo, T. C., Gazdzinski, S., & Meyerhoff, D. J. (2009). 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, 33(8), 1314-1321. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/19413652
http://www.eurekalert.org/pub_releases/2009-05/ace-siw050509.php
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.
http://www.eurekalert.org/pub_releases/2008-04/aaon-ase040208.php
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.
Nixon, S. J., Lawton-Craddock, A., Tivis, R., & Ceballos, N. (2007). Nicotine’s Effects on Attentional Efficiency in Alcoholics. Alcoholism: Clinical and Experimental Research, 31(12), 2083-2091. Retrieved from http://dx.doi.org/10.1111/j.1530-0277.2007.00526.x
http://www.eurekalert.org/pub_releases/2007-11/ace-nme111907.php
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.
Durazzo, T. C., Gazdzinski, S., Rothlind, J. C., Banys, P., & Meyerhoff, D. J. (2006). 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, 30(3), 539-551. Retrieved from http://onlinelibrary.wiley.com/doi/10.1111/j.1530-0277.2006.00060.x/abstract
http://www.eurekalert.org/pub_releases/2006-03/uoc--siw031506.php
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.
Glass, J. M., Adams, K. M., Nigg, J. T., Wong, M. M., Puttler, L. I., Buu, A., … Zucker, R. A. (2006). Smoking is associated with neurocognitive deficits in alcoholism. Drug and Alcohol Dependence, 82(2), 119-126. Retrieved from http://www.sciencedirect.com/science/article/B6T63-4H3Y9PP-2/2/ab85c6bcc93815a6086c1b9440b40b4a
http://www.eurekalert.org/pub_releases/2005-10/uomh-dsc101005.php
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.
Gazdzinski, S., Durazzo, T. C., Studholme, C., Song, E., Banys, P., & Meyerhoff, D. J. (2005). Quantitative Brain MRI in Alcohol Dependence: Preliminary Evidence for Effects of Concurrent Chronic Cigarette Smoking on Regional Brain Volumes. Alcoholism: Clinical and Experimental Research, 29(8), 1484-1495. Retrieved from http://dx.doi.org/10.1097/01.alc.0000175018.72488.61
http://www.eurekalert.org/pub_releases/2005-09/uoc--sst092805.php
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.
Durazzo, T. C., Gazdzinski, S., Banys, P., & Meyerhoff, D. J. (2004). Cigarette Smoking Exacerbates Chronic Alcohol‐Induced Brain Damage: A Preliminary Metabolite Imaging Study. Alcoholism: Clinical and Experimental Research, 28(12), 1849-1860. Retrieved from http://onlinelibrary.wiley.com/doi/10.1097/01.ALC.0000148112.92525.AC/abstract
http://www.eurekalert.org/pub_releases/2004-12/ace-cse120504.php
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.
White, H. K., & Levin, E. D. (2004). Chronic transdermal nicotine patch treatment effects on cognitive performance in age-associated memory impairment. Psychopharmacology, 171(4), 465-471. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/14534771
http://www.eurekalert.org/pub_releases/2003-12/dumc-npm120303.php
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?
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.
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.