Association between intelligence quotient and disability: the role of socioeconomic status

Jacob, Louis and Smith, Lee and Thoumie, Philippe and Haro, Josep M. and Stickley, Andrew and Koyanagi, Ai (2019) Association between intelligence quotient and disability: the role of socioeconomic status. Annals of Physical and Rehabilitation Medicine. ISSN 1877-0665

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Official URL: https://doi.org/10.1016/j.rehab.2019.07.010

Abstract

Objectives: No study has yet investigated the association between intelligence quotient (IQ) and disability [i.e., difficulties in activities of daily living (ADL) or instrumental activities of daily living (IADL)] in the general population. The goal of this nationally representative study was to therefore analyze the potential IQ-disability relationship in England, and to identify influential factors in this association. Methods: Cross-sectional data were analyzed from the 2007 Adult Psychiatric Morbidity Survey (n=6872). IQ was assessed using the National Adult Reading Test (NART), a test that consists of a list of 50 words and is scored by counting the number of errors made in reading out the words. Disability was defined as having difficulties in at least one of the seven domains of ADL and IADL. Regression and mediation analyses were conducted to analyze the association between IQ and disability, and to identify potential factors involved in this relationship. Results: The prevalence of disability increased from 27.7% in the IQ 120-129 group to 51.0% in the IQ 70-79 group. After adjusting for sex, age and ethnicity, compared to those with IQ scores of 120-129, scores of 110-119, 100-109, 90-99, 80-89, and 70-79 were associated with 1.22 [95% confidence interval (CI): 1.01-1.48], 1.42 (95%CI: 1.16-1.72), 1.86 (95%CI: 1.54-2.25), 2.41 (95%CI: 1.92-3.03), and 4.71 (95%CI: 3.56-6.17) times higher odds for disability, respectively. In addition, there was a positive association between a one SD decrease in IQ and disability (odds ratio=1.53, 95%CI: 1.43-1.63). Finally, income (mediated percentage=26.9%), social class (18.0%) and qualification (11.6%) were the strongest influential factors involved in the relationship between IQ and disability, and these socioeconomic factors collectively explained 37.1% of the association. Conclusions: There was a positive association between low IQ and disability in England, and socioeconomic status explained more than one-third of this relationship.

Item Type: Journal Article
Keywords: Intelligence quotient, Disability, England, Epidemiology
Faculty: Faculty of Science & Engineering
Depositing User: Lee Smith
Date Deposited: 31 Jul 2019 14:35
Last Modified: 14 Nov 2019 16:07
URI: http://arro.anglia.ac.uk/id/eprint/704606

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