Social Genomics II: “Air Pollution and the Brain” Anita Webb, PhD JPS Health Network Fort Worth, Texas

Key Points Known: Air pollution can harm lungs Newer: Air pollution can harm brains May damage child’s cognitive abilities Increase risk of adult cognitive decline Possibly increase risk of depression

Review: “Social Genomics I” * Environmental factors can affect gene expression. The environment, including social factors, can ultimately determine genetic profiles. New explanations are emerging for chronic medical problems. *[See PowerPoint at:

Example: Air Pollution Known: Pollution can harm the body – Cardiovascular health – Respiratory health Newer research – Effects on the brain?

Impact on the Brain? Especially, How does air pollution impact: Children’s brain development? Brain function in older adults?

KNOWN: Air pollution is harmful to overall health Also specifically affects the brain – Adult cognitive decline – Possibly depression – P. Mohai – (multiple studies )

“Particulate Matter” Two types in air pollution – “Fine” – “Coarse” Fine particulate matter – Can more easily pass into blood stream – And then into the brain – Causing cognitive decline

[Newer Finding] Coarse particulate matter Is also associated with Cognitive decline. J. Weuve. Arch Int Med (2012)

“Fine Particulate Matter” Pollution from – Power plants, factories, motor vehicles – “1/30 th width of human hair” One of six principal pollutants monitored by the Environmental Protection Agency Research evidence suggests – Harmful cardiovascular effects

“Fine Particulate” More dangerous than “course matter” Example: diesel exhaust Black carbon: “Essentially soot” Boston Studies – Children – Adults

Boston: Children Birth to mean age 10: N = 200+ High levels of factory “black carbon” pollution in their environment Research results – Decreased scores on cognitive tests – Memory, verbal IQ and nonverbal IQ (Am J. Epidemiology 2008)

Boston: Adults Older men, N=680 Decreased scores on cognitive tests – Equal to two years of aging Conclusion: Decline was due to air pollution – Potential Confounds: Traffic noise and gases At risk for cognitive impairment, dementia – (Environ. Health Perspectives 2011)

New York City Children New York City: Fossil fuel exposure (Polycyclic aromatic hydrocarbons) Measured exposure in utero to age 6/7 At age 6/7, fossil fuel exposure correlated with Impaired attention Increased anxiety and depression Perera. Env. Health Perspectives, 2012.

Industrial Pollution Public school children in Michigan In highest industrial pollution areas Correlations: – Lowest attendance rates – Highest failure rates on state testing – Controlling for confounds Including socioeconomic status (P. Mohai et al, 2011)

“Nurses’ Health Study” Women age N>19,000 national sample Compared to controls High level of exposure to particulate pollution For 7-14 years (continued)

Nurses Study (cont.) Conclusion: – Long term exposure – To high levels of pollution – Significantly worsened – Cognitive decline. (J. Weave. Arch. Int. Med. 2012)

Hypothesis The cumulative results of these studies Suggest that particulate air pollution Deserves closer scrutiny As a risk factor For cognitive impairment And perhaps dementia. – (Weir 2012)

Confounding Variables STILL: Must rule out additional traffic factors, i.e. – Noise – Gases [vs. particulate pollution] – Stress (Weuve, J. Arch Int Med. 2012)

Women “Long term exposure “To high levels of pollution “Significantly worsened women’s “Cognitive Decline” – Measured by tests of cognitive skills Both fine and coarse particulate J. Weuve (Arch Int. Med. 2012)

Animal Study Mice exposed to high levels of – Particulate air pollution – 8 hours/day, 5 days/week, x 10 months Brain autopsies found: – Inflammation – Structural changes in hippocampus Decreased dendritic complexity (Correlates with poorer memory)

Mice (continued) Impaired behavior – Decreased performance on maze task – Failure in swim test – Suggestive of “depression” Responded to antidepressant medication Improved performance (Nelson 2011, Molecular Psychiatry)

Mexico City: Dogs Well known air pollution problems Results of autopsies on dog brains – Inflammation and pathology – Amyloid plaques – Neurofibrillary tangles [i.e. Primary markers for Alzheimer’s Disease] – Calderon-Garciduenas – Toxicol. Path. 2003

Mexico City: Children Comparison: – N= 55 children in Mexico City – N=18 children in Mexican town with cleaner air MRI results : Children in Mexico City – “Significantly more likely” to have Brain inflammation Damage in prefrontal cortex – (continued)

Results (continued) Mexico City children test results – Compared to control group Lower Test Scores – Memory, cognitive function and I.Q. Measurable anatomical differences Conclusion: – Pollution can negatively affect the brain

Mechanism of Damage Neuro-inflammation – Disrupts the blood-brain barrier A key factor in many central nervous system disorders, e.g. – Alzheimer’s Disease – Parkinson’s Disease (Brain and Cognition, 2008)

Key Points Known: Air pollution can harm lungs Newer: Air pollution can harm brains May damage child’s cognitive abilities Increase risk of adult cognitive decline Possibly increase risk of depression

Primary Reference Weir, Kirsten “Smog in Our Brains” Monitor on Psychology July/August 2012, 43, (7):