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. 2016;19(5):290-7.
doi: 10.1159/000448912. Epub 2016 Sep 6.

Intellectual Disability in a Birth Cohort: Prevalence, Etiology, and Determinants at the Age of 4 Years

Simone M Karam  1 , Aluísio J D Barros, Alícia Matijasevich, Iná S Dos Santos, Luciana Anselmi, Fernando Barros, Sandra Leistner-Segal, Têmis M Félix, Mariluce Riegel, Sharbel W Maluf, Roberto Giugliani, Maureen M Black
Affiliations

Intellectual Disability in a Birth Cohort: Prevalence, Etiology, and Determinants at the Age of 4 Years

Simone M Karam et al. Public Health Genomics. 2016.

Abstract

Background: Intellectual disability (ID), characterized by impairments in intellectual function and adaptive behavior, affects 1-3% of the population. Many studies investigated its etiology, but few are cohort studies in middle-income countries.

Aims: To estimate prevalence, etiology, and factors related to ID among children prospectively followed since birth in a Southern Brazilian city (Pelotas).

Methods: In 2004, maternity hospitals were visited daily and births were identified. Live-born infants (n = 4,231) whose family lived in the urban area have been followed for several years. At the age of 2 and 4 years, performances in development and intelligence tests were evaluated using the Battelle Developmental Inventory and Wechsler Intelligence Scale, respectively. Children considered as having developmental delay were invited to attend a genetic evaluation.

Results: At 4 years of age, the prevalence of ID was 4.5%, and the etiology was classified into 5 groups: environmental (44.4%), genetic (20.5%), idiopathic (12.6%), neonatal sequelae (13.2%), other diseases (9.3%). Most children presented impairment in two or more areas of adaptive behavior. There was no difference in prenatal care attendance or maternal schooling among the groups.

Conclusion: For about 40% of children, ID was attributed to nonbiological factors, suggesting that the rate may be reduced with appropriate interventions early in life.

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Figures

Fig. 1
Fig. 1
Recruitment for genetic evaluation in the 2004 Pelotas Birth Cohort Study and clinical and laboratory investigations.
See this image and copyright information in PMC

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