Gait and balance disturbances are common in young urbanites and associated with cognitive impairment. Air pollution and the historical development of Alzheimer's disease in the young

Abstract

To determine whether gait and balance dysfunction are present in young urbanites exposed to fine particular matter PM_2.5 ≥ annual USEPA standard, we tested gait and balance with Tinetti and Berg tests in 575 clinically healthy subjects, age 21.0 ± 5.7 y who were residents in Metropolitan Mexico City, Villahermosa and Reynosa. The Montreal Cognitive Assessment was also applied to an independent cohort n:76, age 23.3 ± 9.1 y. In the 575 cohort, 75.4% and 34.4% had abnormal total Tinetti and Berg scores and high risk of falls in 17.2% and 5.7% respectively. BMI impacted negatively Tinetti and Berg performance. Gait dysfunction worsen with age and males performed worse than females. Gait and balance dysfunction were associated with mild cognitive impairment MCI (19.73%) and dementia (55.26%) in 57/76 and 19 cognitively intact subjects had gait and balance dysfunction. Seventy-five percent of urbanites exposed to PM_2.5 had gait and balance dysfunction. For MMC residents-with historical documented Alzheimer disease (AD) and CSF abnormalities, these findings suggest Alzheimer Continuum is in progress. Early development of a Motoric Cognitive Risk Syndrome ought to be considered in city dwellers with normal cognition and gait dysfunction. The AD research frame in PM_2.5 exposed young urbanites should include gait and balance measurements. Multicity teens and young adult cohorts are warranted for quantitative gait and balance measurements and neuropsychological and brain imaging studies in high vs low PM_2.5 exposures. Early identification of gait and balance impairment in young air pollution-exposed urbanites would facilitate multidisciplinary prevention efforts for modifying the course of AD.

Keywords: Air pollution; Alzheimer; Alzheimer continuum; Balance; Berg; Cognition; Dementia; Diesel; Gait; Mexico City; Mild cognitive impairment MCI; MoCA; Motoric cognitive risk syndrome MCR; Nanoparticles; PM (2.5); Tinetti; Young adults.

Fig. 1

PM_2.5 24-hr averages box plots at North East MMC, Villahermosa and Reynosa for 2017. NAAQS stands for National Ambient Air Quality Standards for the USEPA. The continuous line inside the box represents the 24 h median (35 μg/m³) and the dotted line the annual mean (12 μg/m³).

Fig. 2

Trend of maximum of the maxima PM_2.5 24-h average concentrations registered in all PM sampling MMC stations from January 2004 to April 2020 and their comparison against the WHO 24 h mean average (blue solid line) and the US Air Quality Index (AQI) right scale. The beginning of the COVID-19 pandemia February 28, 2020 in MMC is marked. Data correspond to measurements from the manual network of particulate matter of the SEDEMA under a 6-day sampling schedule. Source: http://www.aire.cdmx.gob.mx/default.php#(For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 3

The distribution of the 575 subjects based on their Tinetti and Berg scores. Seventy-five per cent (n:434), had abnormal scores for Total Tinetti scores with 17% (n:99) with high fall risk. Thirty-four percent of subjects (n:221) had abnormal Berg scores and 5.73% (n:33), with high fall risk.