exposure to secondhand smoke and cognitive impairment

7/29/2019 Exposure to Secondhand Smoke and Cognitive Impairment.

1/30

EXPOSURE TO SECONDHANDSMOKE AND COGNITIVE

IMPAIRMENT


2/30

INTRODUCTION Active smoking may be a risk factor for cognitive impairment and

dementia, although it is not clear whether exposure to secondhandsmoke is also a risk factor. The health effects of high levels of exposureto secondhand smoke may be close to those of active smoking,including an increased risk of lung cancer, diabetes, cardiovasculardisease, hypertension, stroke, and death.

As the risks associated with secondhand smoke have become clearer,

an increasing number of governments have decided to legislate againstsmoking in public places. Given the association between exposure tosecondhand smoke and risk factors for cognitive impairment such ascardiovascular disease and stroke, it is possible that such exposuremay be a preventable risk factor for cognitive impairment.

A preliminary analysis of 985 patients (728 women) aged 66-92 yearsfrom the Cardiovascular Health Study was carried out (T J Haight et al,

59th annual meeting of the American Academy of Neurology, Boston,2007) and has been widely reported. Participants who had neversmoked, had no history of cardiovascular disease or dementia, and selfreported long term exposure to secondhand tobacco smoke (living witha smoker for 30 years or more) were about 30% more likely to developdementia over a six year period than those who were not exposed(relative hazard 1.3, 95% confidence interval 0.95 to 1.82).


3/30

Mild Cognitive Impairment

MCI is an intermediate stage between theexpected cognitive decline of normal aging and

the more pronounced decline of dementia.

It involves problems with memory, language,

thinking and judgment that are greater than

typical age-related changes.

your memory or mental function has "slipped."

And your family and close friends may also notice

a change.

But generally these changes aren't severe

enough to interfere with your day-to-day life and

usual activities.


4/30

Causes

no single cause of MCI

Current evidence indicates a number of

neurological and medical conditions probably

contribute to these symptoms.

changes have been identified in autopsy studies

of people with MCI :

o Plaques and tangles, which are microscopic protein

clumps characteristic of Alzheimer's disease

o Lewy bodies, which are microscopic clumps of

another protein associated with Parkinson's

disease, dementia with Lewy bodies

o Small strokes or reduced blood flow through brain

blood vessels


5/30

Brain-imaging studies show that the followingchanges:

o Shrinkage of the hippocampus, a brain region

important for memory

o Plaques (abnormal clumps of beta-amyloid protein)throughout the brain

o Enlargement of the brain's fluid-filled spaces

(ventricles)

o Reduced use of glucose


6/30


7/30

Symptoms

Brain changes as you grow older. People noticegradually increasing forgetfulness as they age.

Cognitive issues may go beyond what's expected

and indicate possible MCI.

o You forget things more often.

o You forget important events such as appointments

or social engagements.


8/30

o You lose your train of thought or the thread ofconversations, books or movies.

o You start to have trouble finding your way around

familiar environments


9/30

Diagnose

Many doctors diagnose MCI based on thefollowing criteria developed by a panel of

international experts:

o You have problems with memory, planning,

following instructions or making decisions

o your ability has declined from a higher level

(confirmed by a family member or a close friend)

o Your overall mental function and daily activities are

not affected


10/30

Neurological exams. Basic tests that indicate how wellyour brain and nervous system are working.

Exams may test:

Reflexes

Eye movements Walking and balance

Sense of touch

Brain imaging MRI or CT scan to check for evidence of a brain

tumor, stroke or bleeding.


11/30

Mental status testingo Draw a clock face with the hands showing a time

specified by the examiner.

o Name today's date and your location.

o Copy a design, such as two intersecting pentagons.

o Follow a three-step command.

o Remember a list of three words spoken to you by

the examiner.

o Follow a written instruction.

o Write down a complete sentence.

o Count backward from 100 by sevens


12/30

Treatment

No MCI drugs or other treatments are specificallyapproved by the Food and Drug Administration

(FDA).

common conditions besides MCI that make you

feel forgetful or less mentally sharp than usual

may be treated

Conditions that can affect memory include:

o High blood pressure

o Depression

o Sleep apnea


13/30

Secondhand Smoke

Secondhand smoke is composed of sidestreamsmoke (the smoke released from the burning end

of a cigarette) and exhaled mainstream smoke

(the smoke exhaled by the smoker).

Old term was ETS, the term secondhand smoke

better captures the involuntary nature of the

exposure.


14/30

The 2006 Surgeon Generals report uses the terminvoluntary because most nonsmokers do not

want to breathe tobacco smoke.

Secondhand smoke has been designated as

a known human carcinogen (cancer-causingagent) by the U.S. Environmental Protection

Agency, the National Toxicology Program, and the

International Agency for Research on Cancer,

and an occupational carcinogen by the NationalInstitute for Occupational Safety and Health.


15/30

Toxic and Poisonous

The National Toxicology Program estimates thatat least 250 chemicals in secondhand smoke are

known to be toxic or carcinogenic (cancer

causing).

Secondhand smoke contains poisonous gases

and chemicals:

o hydrogen cyanide (used in chemical weapons),

o carbon monoxide (found in car exhaust),

o butane (used in lighter fluid),

o ammonia (used in household cleaners),

o toluene (found in paint thinners).


16/30

Some of the toxic metals contained insecondhand smoke include

o arsenic (used in pesticides),

o lead (formerly found in paint),

o chromium (used to make steel),

o cadmium (used to make batteries).


17/30

There are more than 50 cancer-causingchemicals in secondhand smoke :o Polynuclear aromatic hydrocarbons (PAHs) (such

as Benzo[a]pyrene)

o

N-Nitrosamines (such as tobacco-specificnitrosamines)

oAromatic amines (such as 4-aminobiphenyl)

oAldehydes (such as formaldehyde)

o Miscellaneous organic chemicals (such as benzene

and vinyl chloride) ando Inorganic compounds (such as those containing

metals like arsenic, beryllium, cadmium, lead, nickeland radioactive polonium-210).


18/30

11 compounds in tobacco smoke have been identified bythe International Agency for Research on Cancer as Group1 (known human carcinogen) carcinogens.1. 2-naphthylamine,2. 4-aminobiphenyl,3. benzene,4. vinyl chloride,5. ethylene oxide,6. arsenic,7. beryllium,8. nickel compounds,

9. chromium,10. cadmium and11. polonium-210


19/30


20/30

EXPOSURE

At work

In public places

At home

In the car


21/30

THE CORRELATION

Research Methodo Participants were from the 1998, 1999, and

2001waves of the Health Survey for England who

also participated in the 2002 wave of the English

Longitudinal Study of Ageing.o The core sample of the English Longitudinal Study

of Ageing is limited to adults aged 50 years or more

in 2002 and is drawn from the Health Survey for

England sample by postcode sector, stratified byhealth authority and proportion of households in

non-manual socioeconomic groups


22/30

oAnalyses was restricted to the subsample of 5265non-smoking participants whose salivary cotinine

levels were measured. A number of participants

were excluded upon particular reasons and

remaining 4809 participants formed the sample forthe analyses.


23/30

Measuring exposure

research used levels of salivary cotinine (ng/ml)measured in the Health Survey for England as a

biomarker for recent exposure to secondhand

smoke

Cotinine levels were analysed using a gaschromatograph machine with a rapid liquid

chromatography technique


24/30

Examining Cognitive impairment

Assessed using neuropsychological testsincorporated in the English Longitudinal Study of

Ageing

o attention and processing speed were assessed

using the letter cancellation task from the MedicalResearch Council National Study of Health and

Development.

o Time orientation was assessed using questions

from the mini-mental state examination.o Immediate and delayed verbal memory were

assessed using a 10-word learning task from the

Health and Retirement Study.


25/30

Prospective memory was assessed by askingparticipants to remember to write their initials inthe top left corner of a piece of paper on aclipboard when it was handed to them later in the

session , and by asking participants to remind theinterviewer to record the time when he or sheannounced that the cognitive section wasfinished.

Numeracy was assessed using questions relating

to simple calculations based on everydaysituations

The semantic verbal fluency task was taken fromthe Cambridge cognitive examination

(CAMCOG), which examines how many unique


26/30

Results

Those with high levels of salivary cotinine (0.8-13.5 ng/ml) were more likely to be cognitively

impaired than those exposed to little or no

secondhand smoke (0.0-0.1 ng/ml).

Former smokers exposed to the highest levels ofsecondhand smoke also had increased odds of

cognitive impairment although this association

was weaker than that observed for never smokers


27/30

Possible mechanisms

Exposure to secondhand smoke is associatedwith an increased risk of cardiovascular disease,

and cardiovascular disease may in turn be

associated with an increased risk of cognitive

impairment and dementia. study discovered that short term exposure to

secondhand smoke adversely affects endothelial

function in ways that immediately compromise the

cardiovascular system. Dysfunctional endothelialcells contribute to vasoconstriction,

atherogenesis, and thrombosis

therefore compromise the blood supply to the

brain.


28/30

Exposure to secondhand smoke is also a riskfactor for incident stroke, and differences in

subclinical cerebrovascular disease may help to

explain the noticeable individual differences in

cognitive function observed during late adulthood


29/30

Conclusion

The results suggest that in a large diverse sample ofnon-smoking adults, high levels of cotinine may beassociated with increased odds of cognitiveimpairment.

Given the ongoing international policy debate on

exposure to secondhand smoke, this is a topic ofmajor public health significance.

Prospective nationally representative studies of theassociation between biomarkers of exposure tosecondhand smoke and cognitive decline anddementia are therefore warranted to assess therelation between secondhand smoke and cognitivehealth with greater precision.

In the meantime, current results provide newevidence to suggest that exposure to secondhandsmoke may be associated with increased odds of

cognitive impairment.


30/30

Referrences1. Llewellyn D, Lang I, Langa K, et al. Exposure to secondhand smoke andcognitive impairment in non-smokers: national cross sectional study with

cotinine measurement. BMJ 2009;338:b462.

2. The Health Consequences of Involuntary Exposure to TobaccoSmoke. Executive Summary. Surgeon General of the United States. 2006.Retrieved 2009-01-28.

3. Bennett DA, Wilson RS, Schneider JA, Evans DA, Beckett LA, Aggarwal NT, etal. Natural history of mild cognitive impairment in older persons. Neurology

2002;59:198-205.4. Taylor R, Conway L, Calderwood L, Lessof C. Methodology. In:

MarmotM,Banks J,Blundell R, LessofC,Nazroo J, eds. Health,wealth andlifestyles of the older population in England: the 2002 English LongitudinalStudy of Ageing. London: Institute of Fiscal Studies, 2003:357-74.

5. NYU medical center. Mild Cognitive Impairment. Available at:http://www.med.nyu.edu/adc/forpatients/cognitiveimpair.html#causes.

Accessed on 22nd

July 2011.6. Mayo clinic. Mild cognitive impairment. Available at:

http://www.mayoclinic.com/health/mild-cognitive-impairment/DS00553.Accessed on 22nd July 2011.

7. American Cancer Society. Secondhand smoke. Available at:http://www.cancer.org/Cancer/CancerCauses/TobaccoCancer/secondhand-smoke. Accessed on 22nd July 2011.
http://en.wikipedia.org/wiki/Surgeon_General_of_the_United_Stateshttp://www.med.nyu.edu/adc/forpatients/cognitiveimpair.htmlhttp://www.mayoclinic.com/health/mild-cognitive-impairment/DS00553http://www.cancer.org/Cancer/CancerCauses/TobaccoCancer/secondhand-smokehttp://www.cancer.org/Cancer/CancerCauses/TobaccoCancer/secondhand-smokehttp://www.cancer.org/Cancer/CancerCauses/TobaccoCancer/secondhand-smokehttp://www.cancer.org/Cancer/CancerCauses/TobaccoCancer/secondhand-smokehttp://www.cancer.org/Cancer/CancerCauses/TobaccoCancer/secondhand-smokehttp://www.mayoclinic.com/health/mild-cognitive-impairment/DS00553http://www.mayoclinic.com/health/mild-cognitive-impairment/DS00553http://www.mayoclinic.com/health/mild-cognitive-impairment/DS00553http://www.mayoclinic.com/health/mild-cognitive-impairment/DS00553http://www.mayoclinic.com/health/mild-cognitive-impairment/DS00553http://www.med.nyu.edu/adc/forpatients/cognitiveimpair.htmlhttp://en.wikipedia.org/wiki/Surgeon_General_of_the_United_States

exposure to secondhand smoke and cognitive impairment

Documents