Air Pollution, Stress, and Allostatic Load: Linking Systemic and Central Nervous System Impacts

Abstract

Air pollution is a risk factor for cardiovascular and respiratory morbidity and mortality. A growing literature also links exposure to diverse air pollutants (e.g., nanoparticles, particulate matter, ozone, traffic-related air pollution) with brain health, including increased incidence of neurological and psychiatric disorders such as cognitive decline, dementia (including Alzheimer's disease), anxiety, depression, and suicide. A critical gap in our understanding of adverse impacts of pollutants on the central nervous system (CNS) is the early initiating events triggered by pollutant inhalation that contribute to disease progression. Recent experimental evidence has shown that particulate matter and ozone, two common pollutants with differing characteristics and reactivity, can activate the hypothalamic-pituitary-adrenal (HPA) axis and release glucocorticoid stress hormones (cortisol in humans, corticosterone in rodents) as part of a neuroendocrine stress response. The brain is highly sensitive to stress: stress hormones affect cognition and mental health, and chronic stress can produce profound biochemical and structural changes in the brain. Chronic activation and/or dysfunction of the HPA axis also increases the burden on physiological stress response systems, conceptualized as allostatic load, and is a common pathway implicated in many diseases. The present paper provides an overview of how systemic stress-dependent biological responses common to particulate matter and ozone may provide insight into early CNS effects of pollutants, including links with oxidative, inflammatory, and metabolic processes. Evidence of pollutant effect modification by non-chemical stressors (e.g., socioeconomic position, psychosocial, noise), age (prenatal to elderly), and sex will also be reviewed in the context of susceptibility across the lifespan.

Urban Ambient Air Pollution and Behavioural Disorders

“…To the best of our knowledge, this is the first study that examined the association between the exposure to ambient carbon monoxide and behavioural disorders. Our findings support previous studies that investigated mental health issues [2,3,6,7]. As Figure 1 indicates carbon monoxide shows the associations with various mental health conditions.…”

“…In recently published article by Thomson, the author wrote in the abstract: "The present paper provides an overview of how systemic stress-dependent biological responses common to particulate matter and ozone may provide insight into early the central nervous system effects of pollutants, including links with oxidative, inflammatory, and metabolic processes [7]". In his paper the author explains biological aspect of air pollutants which can act as stressors and elicit endocrine stress responses.…”

Auswirkungen von Umweltrisikofaktoren wie Lärm und Luftverschmutzung auf die psychische Gesundheit: Was wissen wir?

“…beschleunigen [8]. Auf zerebraler Ebene kann die chronische Aktivierung und Dysregulation der Hypothalamus-Hypophysen-Nebennierenrinden-Achse die Entstehung von oxidativem Stress und neuroinflammatorischen Prozessen begünstigen, allesamt Faktoren, die mit psychischen Erkrankungen assoziiert sind [14]. Auch ist hier von einer Wechselwirkung auszugehen -Depressionen fördern über stressinduzierte chronische Inflammation das Auftreten von kardiovaskulären Erkrankungen, wobei proinflammatorische Prozesse das Auftreten von Depressionen begünstigen [7].…”

Residential exposure to air pollution, access to neighborhood greenspace and their association with hair cortisol concentrations in the second and third trimester of pregnancy

“…Air pollutants may induce oxidative stress and low grade in ammation [51]. Depending on size and chemical composition, inhaled air pollution constituents may translocate from the lungs to the systemic circulation or migrate via olfactory transport to the brain and directly interact with brain tissues including the hypothalamus [11]. During pregnancy, oxidative stress is known to be higher than in the non-pregnant state; residential exposure to air pollutants and road tra c may further amplify the level of maternal oxidative stress [52].…”

“…The biological pathways that relate maternal exposure to air pollution to adverse pregnancy outcomes however, remain incompletely understood. Recent experimental animal research has shown that a neuroendocrine stress response is among the early biological responses triggered by exposure to ne particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM 2.5 ) and exposure to nitrogen dioxide (NO 2 ) [11]. The biological stress response includes activation of the hypothalamic-pituitary-adrenal (HPA) axis and release of glucocorticoid stress hormones, with the glucocorticoid cortisol as its main downstream effector in humans [12].…”