Are the effects of lead exposure linked to the g factor? A meta-analysis

Michael A. Woodley of Menie, Jan te Nijenhuis, Vladimir Shibaev, Miao Li, Jan Smit

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Does lead reduce IQ at the level of g, test specificities, or both? A bare-bones psychometric meta-analysis utilizing the Method of Correlated Vectors was performed on a sample of 16 studies for which subtest-level data could be obtained satisfying stringent inclusion rules. The aggregate correlation across samples between subtest-level estimates of both g loading (g) and the deleterious impact of lead exposure (d) was 0.10 (K = 16, total N = 1935, 80% CI after correction for sampling error = 0.10 to 0.10). So, lead exposure is associated with a slightly positive vector correlation, which is consistent with the results of other studies examining the effects of other neurotoxins on IQ using MCV; this outcome is consistent with two scenarios. The first is that lead exposure may have effects on both g and test specificities owing to systemic effects on many different brain regions. The second is that two antagonistic factors are at work. It might be that the ‘control’ and exposure groups used in these kinds of studies are confounded with pre-existing differences in g – lower g being a risk factor for poorer life outcomes (including lower socioeconomic status and concomitantly heightened risk of lead exposure), whereas lead has it's primary effect on the test specificities, with both effects opposing one another, as reflected in the small magnitude vector correlation value. Strategies for distinguishing between these scenarios are discussed.

Original languageEnglish
Pages (from-to)184-191
Number of pages8
JournalPersonality and Individual Differences
Volume137
Early online date10 Sep 2018
DOIs
Publication statusPublished - 15 Jan 2019

Fingerprint

Meta-Analysis
Selection Bias
Neurotoxins
Psychometrics
Social Class
Bone and Bones
Control Groups
Lead
Brain

Keywords

  • g factor
  • Intelligence
  • Lead exposure

Cite this

Woodley of Menie, Michael A. ; te Nijenhuis, Jan ; Shibaev, Vladimir ; Li, Miao ; Smit, Jan. / Are the effects of lead exposure linked to the g factor? A meta-analysis. In: Personality and Individual Differences. 2019 ; Vol. 137. pp. 184-191.
@article{6ebae4a1f29e4341b9d2242a8f718749,
title = "Are the effects of lead exposure linked to the g factor? A meta-analysis",
abstract = "Does lead reduce IQ at the level of g, test specificities, or both? A bare-bones psychometric meta-analysis utilizing the Method of Correlated Vectors was performed on a sample of 16 studies for which subtest-level data could be obtained satisfying stringent inclusion rules. The aggregate correlation across samples between subtest-level estimates of both g loading (g) and the deleterious impact of lead exposure (d) was 0.10 (K = 16, total N = 1935, 80{\%} CI after correction for sampling error = 0.10 to 0.10). So, lead exposure is associated with a slightly positive vector correlation, which is consistent with the results of other studies examining the effects of other neurotoxins on IQ using MCV; this outcome is consistent with two scenarios. The first is that lead exposure may have effects on both g and test specificities owing to systemic effects on many different brain regions. The second is that two antagonistic factors are at work. It might be that the ‘control’ and exposure groups used in these kinds of studies are confounded with pre-existing differences in g – lower g being a risk factor for poorer life outcomes (including lower socioeconomic status and concomitantly heightened risk of lead exposure), whereas lead has it's primary effect on the test specificities, with both effects opposing one another, as reflected in the small magnitude vector correlation value. Strategies for distinguishing between these scenarios are discussed.",
keywords = "g factor, Intelligence, Lead exposure",
author = "{Woodley of Menie}, {Michael A.} and {te Nijenhuis}, Jan and Vladimir Shibaev and Miao Li and Jan Smit",
year = "2019",
month = "1",
day = "15",
doi = "10.1016/j.paid.2018.09.005",
language = "English",
volume = "137",
pages = "184--191",
journal = "Personality and Individual Differences",
issn = "0191-8869",
publisher = "Elsevier BV",

}

Are the effects of lead exposure linked to the g factor? A meta-analysis. / Woodley of Menie, Michael A.; te Nijenhuis, Jan; Shibaev, Vladimir; Li, Miao; Smit, Jan.

In: Personality and Individual Differences, Vol. 137, 15.01.2019, p. 184-191.

Research output: Contribution to JournalArticleAcademicpeer-review

TY - JOUR

T1 - Are the effects of lead exposure linked to the g factor? A meta-analysis

AU - Woodley of Menie, Michael A.

AU - te Nijenhuis, Jan

AU - Shibaev, Vladimir

AU - Li, Miao

AU - Smit, Jan

PY - 2019/1/15

Y1 - 2019/1/15

N2 - Does lead reduce IQ at the level of g, test specificities, or both? A bare-bones psychometric meta-analysis utilizing the Method of Correlated Vectors was performed on a sample of 16 studies for which subtest-level data could be obtained satisfying stringent inclusion rules. The aggregate correlation across samples between subtest-level estimates of both g loading (g) and the deleterious impact of lead exposure (d) was 0.10 (K = 16, total N = 1935, 80% CI after correction for sampling error = 0.10 to 0.10). So, lead exposure is associated with a slightly positive vector correlation, which is consistent with the results of other studies examining the effects of other neurotoxins on IQ using MCV; this outcome is consistent with two scenarios. The first is that lead exposure may have effects on both g and test specificities owing to systemic effects on many different brain regions. The second is that two antagonistic factors are at work. It might be that the ‘control’ and exposure groups used in these kinds of studies are confounded with pre-existing differences in g – lower g being a risk factor for poorer life outcomes (including lower socioeconomic status and concomitantly heightened risk of lead exposure), whereas lead has it's primary effect on the test specificities, with both effects opposing one another, as reflected in the small magnitude vector correlation value. Strategies for distinguishing between these scenarios are discussed.

AB - Does lead reduce IQ at the level of g, test specificities, or both? A bare-bones psychometric meta-analysis utilizing the Method of Correlated Vectors was performed on a sample of 16 studies for which subtest-level data could be obtained satisfying stringent inclusion rules. The aggregate correlation across samples between subtest-level estimates of both g loading (g) and the deleterious impact of lead exposure (d) was 0.10 (K = 16, total N = 1935, 80% CI after correction for sampling error = 0.10 to 0.10). So, lead exposure is associated with a slightly positive vector correlation, which is consistent with the results of other studies examining the effects of other neurotoxins on IQ using MCV; this outcome is consistent with two scenarios. The first is that lead exposure may have effects on both g and test specificities owing to systemic effects on many different brain regions. The second is that two antagonistic factors are at work. It might be that the ‘control’ and exposure groups used in these kinds of studies are confounded with pre-existing differences in g – lower g being a risk factor for poorer life outcomes (including lower socioeconomic status and concomitantly heightened risk of lead exposure), whereas lead has it's primary effect on the test specificities, with both effects opposing one another, as reflected in the small magnitude vector correlation value. Strategies for distinguishing between these scenarios are discussed.

KW - g factor

KW - Intelligence

KW - Lead exposure

UR - http://www.scopus.com/inward/record.url?scp=85053036341&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85053036341&partnerID=8YFLogxK

U2 - 10.1016/j.paid.2018.09.005

DO - 10.1016/j.paid.2018.09.005

M3 - Article

VL - 137

SP - 184

EP - 191

JO - Personality and Individual Differences

JF - Personality and Individual Differences

SN - 0191-8869

ER -