Neurobehavioral test performance among apprentice painters: baseline data

A systematic review of the mental health risks and resilience among pollution-exposed adolescents

Pollution is harmful to human physical health and wellbeing. What is less well established is the relationship between adolescent mental health - a growing public health concern - and pollution. In response, we systematically reviewed studies documenting associations between pollution and mental health in adolescents. We searched Africa Wide, Medline, PsycArticles, PsycInfo, PubMed, CINAHL, ERIC, SciELO, Scopus, and Web of Science Core Collection for studies published up to 10 April 2020 that investigated exposure to any pollutant and symptoms of anxiety; depression; disruptive, impulse-control, and conduct disorders; neurodevelopmental disorders; psychosis; or substance abuse in 10-24-year-olds (i.e., adolescents as per expanded and more inclusive definition of adolescence). This identified 2291 records and we assessed 128 papers for inclusion. We used a narrative synthesis to coalesce the studies' findings. This review is registered on PROSPERO, CRD42020176664. Seventeen studies from Asia, Europe, the Middle East, and North America were included. Air and water pollution exposure was associated with elevated symptoms of depression, generalised anxiety, psychosis, and/or disruptive, impulse control and conduct disorder. Exposure to lead and solvents was associated with neurodevelopmental impairments. Most studies neglected factors that could have supported the mental health resilience of adolescents exposed to pollution. Notwithstanding the limited quality of most reviewed studies, results suggest that pollution exposure is a risk to adolescent mental health. High-quality research is urgently required, including the factors and processes that protect the mental health of pollution-exposed adolescents. Studies with adolescents living in low- and lower middle-income countries and the southern hemisphere must be prioritized.

The impact of solvent mixtures on neurobehavioral performance: conclusions from epidemiological data

The review of epidemiological studies investigating the neurobehavioral effects of occupational exposure to solvent mixtures sought to contribute to the following issues: (1) Identification of affected cognitive and motor functions. (2) Identification of sensitive neuropsychological tests. (3) Analysis of exposure-effect relationships. The approach was based on the meta-analytical method of effect size estimates. Fifty-three groups from occupational studies were included in the meta-analysis. Forty-eight neuropsychological performance variables could be analyzed as they were included in at least three studies. Seventeen articles provided detailed information on the constituents of mixtures, thereby enabling the computation of an exposure index that allowed the comparison of different mixtures. Significant negative effect sizes were obtained for 12 test variables measuring attention, memory, motor performance and constructional abilities. The greatest proportion of lower performance scores in the exposed groups was shown by different tests of attention: significant effect sizes between d=-0.16 and -0.46 were calculated. Tests of cognitive processing speed, response alternation and inhibition seemed to be sensitive tools for the detection of poorer performance. Exposure-effect relationships were mainly characterized by inconsistent patterns. Crude and inappropriately calculated exposure measures were blamed for this outcome. A healthy worker effect was suggested more consistently: studies examining groups with longer exposure duration obtained smaller effect sizes. Indications of confounding were observed; however, they did not seem sufficient to question consistent effect size patterns. Paying greater attention to the measurement of exposure and including measures of confounding is advisable for future studies and would enhance the explanatory power of cross-sectional studies and meta-analyses.

Comparison of potential adjustment variables representing primary intellectual level in epidemiological studies on neurotoxicity

BACKGROUND

Primary intellectual abilities (PIA) are a confounder in epidemiological studies on neurotoxicity. A good measure of this confounder should be independent of age as PIA is an intrinsic ability. Furthermore, as PIA is related to health endpoints, any measure of PIA should reveal this association. This study is aimed at comparing vocabulary test, diploma and age at end of schooling properties as measures of PIA in a non-exposed population of workers.

METHODS

The design was a cross-sectional study of 413 non-exposed workers (203 women and 210 men) selected from a health check-up center. The effect of age on the vocabulary score was assessed using an analysis of covariance adjusted for diploma. Relationships between neuropsychological performances and vocabulary score, diploma and end of schooling age were, respectively, assessed using multiple linear regressions adjusted for age and gender.

RESULTS

Vocabulary score increased significantly with age, both for men and women. The increase was 0.14 word per year for women, and 0.18 word per year for men. The explained variance of the models evaluating the relationships between age at end of schooling, diploma, vocabulary test, and neuropsychological performances was quite similar for the three measures of PIA.

CONCLUSIONS

Vocabulary score was found to be age-related, even after adjustment for diploma. No difference was found between these three variables in terms of their relationship to neuropsychological endpoints. Moreover, the literature shows that vocabulary test performances are influenced by exposure to neurotoxic agents. These results suggest that vocabulary score could be of interest for participants of similar ages and similar diplomas. Otherwise, the other two variables would be better PIA measures in neurotoxicology studies.

Neurobehavioral test performance in the third National Health and Nutrition Examination Survey

The third National Health and Nutrition Examination Survey (NHANES III) contained three computerized neurobehavioral tests from the Neurobehavioral Evaluation System (NES): simple reaction time, symbol-digit substitution and serial digit learning. The neurobehavioral data that were collected came from a nationally representative sample of adults 20-59 years old. Performance on the tests was related to sex, age, education level, family income and race-ethnicity. Performance decreased as age increased, and increased as education level and family income increased. Differences in performance between sexes, levels of education and racial-ethnic groups tended to decrease as family income increased. The relationship between age and performance on the symbol-digit substitution test varied by education level and by racial-ethnic group. The relationship between age and performance on the serial digit learning test varied by racial-ethnic group. Questionnaire variables that were related to performance on one or more of the tests included the reported amount of last night's sleep, energy level, computer or video game familiarity, alcoholic beverages within the last 3 h and effort. Persons who took the tests in English or Spanish performed differently on the symbol-digit substitution and serial digit learning tests. Performance on all the tests decreased as test room temperature increased.