INDOOR AIR POLLUTION AND COGNITIVE FUNCTION AMONG OLDER

MEXICAN ADULTS

Joseph L. Saenz, Ph.D.Rebeca Wong, Ph.D.

Jennifer Ailshire, Ph.D.

Air pollution and cognitive function• Growing evidence that exposure to high

levels of air pollution can negatively affect cognition (Calderón et al,. 2002; Weuve et al., 2012; Oudin et al., 2016).

• The majority of studies of air pollution and health have focused on outdoor air pollution.

• Fewer studies have investigated the cognitive effects of exposure to sources of air pollution inside the home.

What is indoor air pollution?• Air pollution resulting from the indoor combustion

of biomass for domestic energy (cooking, heating, lighting).

• Approximately half of the world uses solid fuels for cooking.

• Up to 90% of rural households in developing countries.

• When these materials are burned inside with poor ventilation, exposure to particulate matter can far exceed the World Health Organization standards (Bruce, 2000).

Reproduced from: http://www.humanosphere.org/basics/2013/07/data-show-indoor-air-pollution-a-major-killer-of-kids/

Indoor Air Pollution

Reproduced from Maldonado, I. N. P., Álvarez, L. G. P., Díaz-Barriga, F., Esquivel, L. E. B., & Pérez, F. J. (2011). Indoor Air Pollution in Mexico in The Impact of Air Pollution on Health, Economy, Environment and Agricultural Sources, 373-390.

Reproduced from Bruce, N., Perez-Padilla, R., & Albalak, R. (2000). Indoor air pollution in developing countries: a major environmental and public health challenge. Bulletin of the World Health organization, 78(9), 1078-1092.

Indoor air pollution and health• Previous work has suggested associations between

exposure to indoor air pollution and:• Chronic obstructive pulmonary disease• Asthma • Lung cancer• Low birth weight• Infant mortality

• 4.3 million premature deaths in 2012 (WHO, 2014)• We evaluate the association between indoor air

pollution and cognitive function in Mexico.• Developing country, rapid aging.

Percentage of fuel wood users (2000)

Mexico City

Guadalajara

Monterrey

Reproduced from Masera O.R, Drigo R., and Trossero M.A. 2003. Woodfuels integrated supply/demand overview mapping. Universidad Autónoma de México, FAO-EC Partnership Programme. Food and Agriculture Organization of the United Nations

OaxacaChiapas

Data & Methods• The Mexican Health and Aging Study (MHAS) –

large, longitudinal, household based, sample of older Mexican adults (age 50+) and their spouses.

• Data collected 2001 - 2015.• 15,723 interviewed in 2012.• I include 13,309 respondents age 50+ with

information on cognitive function.

Indoor Air Pollution:• Respondents are asked “the fuel that you use most to

cook is…?”• Gas• Wood or coal• Other (oil, electricity, other) ~ 1% of sample.

Cognitive function• Cognitive function is assessed in the MHAS using the

Cross-Cultural Cognitive Examination (CCCE)• Especially useful in populations with limited literacy

and mathematical abilities (Glosser et al., 1993)• Domains of cognitive function include:

• Immediate recall (0-8)• Delayed recall (0-8)• Attention (0-60)• Verbal fluency (0-80)• Orientation (0-3)

Statistical Method and Covariates• Each cognitive domain score is modeled using ordinary least

squares regression.• The association between indoor air pollution exposure and

cognitive function is estimated while controlling for individual and household characteristics.

Gas84.0%

Wood or Coal16.0%

Reported Primary Cooking Fuel*

*Results are weighted using 2012 person weights.

Type of Cooking Fuel by Community Size*

98.7% 94.3%79.3%

46.5%

1.3% 5.7%20.7%

53.5%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

100,000+ 15,000-99,999 2,500-14,999 <2,500

Perc

ent R

epor

t Fue

l Typ

e

Community Size

Gas Wood/Coal*Results are weighted using 2012 person weights.

Urban Rural

Descriptive Results

Household Cooking Fuel: Gas Wood/Coal p% %

DemographicsFemale 54.7 50.8 **

Age, years 62.3 63.9Years of Education, years 6.5 2.5 ***

SmokingNever Smoker 59.5 65.5

***Former Smoker 25.7 24.5Current Smoker 14.8 10.1

HealthChronic Conditions 0.82 0.75 ***

Insured 86.2 80.5 ****Results are weighted using 2012 person weights.

Parameter Estimates of Use of Wood or Coal as Cooking Fuel on Immediate Recall

• Model 1 includes age, sex, educational attainment, and locality size.

• Model 2 adds quartiles of wealth.

• Model 3 adds household characteristics (wall, floor, ceiling materials, plumbing type, use of insecticide).

• Model 4 adds chronic conditions, health insurance, and smoking.-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

0.05Model 1 Model 2 Model 3 Model 4

Para

met

er E

stim

ate

and

95%

Con

fiden

ce In

terv

al

Immediate Recall

Parameter Estimates of Use of Wood or Coal as Cooking Fuel on Attention Measure

• Model 1 includes age, sex, educational attainment, and locality size.

• Model 2 adds quartiles of wealth.

• Model 3 adds household characteristics (wall, floor, ceiling materials, plumbing type, use of insecticide).

• Model 4 adds chronic conditions, health insurance, and smoking.

-6

-5

-4

-3

-2

-1

0

1Model 1 Model 2 Model 3 Model 4

Para

met

er E

stim

ate

and

95%

Con

fiden

ce In

terv

al

Attention

Parameter Estimates of Use of Wood or Coal as Cooking Fuel on Orientation

• Model 1 includes age, sex, educational attainment, and locality size.

• Model 2 adds quartiles of wealth.

• Model 3 adds household characteristics (wall, floor, ceiling materials, plumbing type, use of insecticide).

• Model 4 adds chronic conditions, health insurance, and smoking.

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

0.05Model 1 Model 2 Model 3 Model 4

Para

met

er E

stim

ate

and

95%

Con

fiden

ce In

terv

al

Orientation

Parameter Estimates of Use of Wood or Coal as Cooking Fuel on Verbal Fluency

• Model 1 includes age, sex, educational attainment, and locality size.

• Model 2 adds quartiles of wealth.

• Model 3 adds household characteristics (wall, floor, ceiling materials, plumbing type, use of insecticide).

• Model 4 adds chronic conditions, health insurance, and smoking.

-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2Model 1 Model 2 Model 3 Model 4

Para

met

er E

stim

ate

and

95%

Con

fiden

ce In

terv

al

Verbal Fluency

Fully Adjusted Parameter Estimates of Wood/Coal Use as Cooking Fuel in Terms of Age and Years of Education

3.3

6.5

5.7

6.0

-1.6

-2.4

-2.0

-3.0

-4 -2 0 2 4 6 8

Immediate Recall

Attention

Verbal Fluency

Orientation

Years of Education Years of Age

Sensitivity Analysis: Number of Waves Reporting Use of Wood/Coal as Cooking Fuel

• Percentages calculated based on OLS regressions of cognitive scores holding age, sex, years of education, and locality size constant at their means.

-3.70%

-6.77%

-3.46%

-5.47%

-1.85%

-10.14%

-4.76%

-6.64%

-4.32%

-17.85%

-8.41%

-12.11%

-20%

-18%

-16%

-14%

-12%

-10%

-8%

-6%

-4%

-2%

0%Immediate Recall Attention Verbal Fluency Orientation

% L

ower

than

Nev

er R

epor

ting

Biom

ass f

or F

uel

Cognitive Domains by Number of Reports of Biomass as Fuel

1 Report 2 Reports 3 Reports

***

***

**

***

***

**

***

***

***

***

***

Discussion• Exposure to indoor air pollution was associated with

decreased performance on immediate recall, attention, orientation, and verbal fluency domains. • Effects were equivalent to approximately:

• 3-6 years of age• 1.5-3 years of education

Solutions and Challenges• Reduce exposure to indoor air pollution by:

• Promoting cleaner fuel sources.• Improving ventilation in homes.

• Many households using wood/coal as cooking fuel are located in remote areas.

• Difficult to reach • Limited access to alternative fuel sources• Alternative sources of energy not affordable. • Indigenous population groups are highly

traditional.• Require collaboration with members and

leaders of indigenous communities.

Acknowledgements• This study was conducted with the support of the Davis School of

Gerontology at the University of Southern California, and by the Multidisciplinary Research Training in Gerontology Training Grant (T32AG000037) from the National Institutes of Health/National Institute on Aging.

• This research was supported by the National Institute on Aging of the National Institutes of Health under Award Number P30AG043073. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

• The MHAS is partly sponsored by the National Institutes of Health/National Institute on Aging (grant number NIH R01AG018016). Data files and documentation are public use and available at www.MHASweb.org.

References• Weuve, J., Puett, R. C., Schwartz, J., Yanosky, J. D., Laden, F., & Grodstein, F. (2012). Exposure to particulate air pollution and cognitive decline in older

women. Archives of internal medicine, 172(3), 219-227.• Calderón-Garcidueñas, L., Azzarelli, B., Acuna, H., Garcia, R., Gambling, T. M., Osnaya, N., ... & Rewcastle, B. (2002). Air pollution and brain

damage. Toxicologic pathology, 30(3), 373-389.• Oudin, A., Forsberg, B., Adolfsson, A. N., Lind, N., Modig, L., Nordin, M., ... & Nilsson, L. G. (2016). Traffic-related air pollution and dementia incidence

in Northern Sweden: a longitudinal study. Environmental health perspectives, 124(3), 306.• Bruce, N., Perez-Padilla, R., & Albalak, R. (2000). Indoor air pollution in developing countries: a major environmental and public health

challenge. Bulletin of the World Health organization, 78(9), 1078-1092.• Maldonado, I. N. P., Álvarez, L. G. P., Díaz-Barriga, F., Esquivel, L. E. B., & Pérez, F. J. (2011). Indoor Air Pollution in Mexico in The Impact of Air Pollution

on Health, Economy, Environment and Agricultural Sources, 373-390.• WHO. Household air pollution and health Key facts [internet document] World Health Organization, 2014 [consulted February 11, 2016] [1 screen].

Available in: http://www.who.int/mediacentre/factsheets/fs292/en/• Serrano-Medrano M, Arias-Chalico T, Ghilardi A, Masera O. Spatial and temporal projection of fuelwood and charcoal consumption in Mexico. Energy

Sustain Develop 2014;19:39-46. http://doi.org/bs3r• Masera O.R, Drigo R., and Trossero M.A. 2003. Woodfuels integrated supply/demand overview mapping. Universidad Autónoma de México, FAO-EC

Partnership Programme. Food and Agriculture Organization of the United Nations • Glosser, G., Wolfe, N., Albert, M. L., Lavine, L., Steele, J. C., Calne, D. B., & Schoenberg, B. S. (1993). Cross-Cultural Cognitive Examination: Validation of

a Dementia Screening Instrument for Neuroepidemiological Research. Journal of the American Geriatrics Society, 41(9), 931-939.

INDOOR AIR POLLUTION AND COGNITIVE FUNCTION AMONG OLDER

MEXICAN ADULTS

Joseph L. Saenz, Ph.D.Rebeca Wong, Ph.D.

Jennifer Ailshire, Ph.D.