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Risks for severe mental retardation occurring in isolation and with other developmental disabilities

Laura L Jelliffe-Pawlowski1, Gary M Shaw, Verne Nelson

  • 1March of Dimes Birth Defect Foundation, California Birth Defects Monitoring Program, Berkeley, USA. ljelliff@dhs.ca.gov

American Journal of Medical Genetics. Part A
|June 9, 2005
PubMed

Insights

Low birth weight and preterm birth significantly increase the risk of severe mental retardation (SMR), with or without cerebral palsy or epilepsy. Risk factors for SMR with pervasive developmental disorder (PDD) vary by sex and race.

Area of Science:

  • Epidemiology
  • Developmental Pediatrics
  • Public Health

Background:

  • Severe mental retardation (SMR) is a complex condition with multifactorial etiologies.
  • Understanding risk factors is crucial for targeted interventions and prevention strategies.
  • Previous research has identified various individual and maternal characteristics associated with SMR.

Purpose of the Study:

  • To investigate individual and maternal risk factors for severe mental retardation (SMR).
  • To explore associations between SMR and co-occurring conditions: cerebral palsy (CP), epilepsy, and pervasive developmental disorder (PDD).
  • To examine differential risk profiles for SMR based on diagnostic subcategories.

Main Methods:

  • Cohort study of 119,404 children born in California Central Valley (1992-1993) without Down syndrome.
  • Analysis of individual and maternal characteristics as potential risk factors.
  • Use of unadjusted and adjusted relative risks (RRs) with 95% confidence intervals (CIs) from Poisson distribution.

Main Results:

  • Children born low-birth-weight or preterm exhibited substantially increased risks for SMR (RRs 2.6-9.9), with or without CP or epilepsy.
  • Males, Black children, and Asian children had a higher risk of SMR occurring with PDD compared to females and White children, respectively.
  • Significant RRs were observed for SMR with PDD: males (RR=3.4), Blacks (RR=5.1), and Asians (RR=3.9).

Conclusions:

  • Low birth weight and preterm birth are significant risk factors for SMR, particularly when co-occurring with CP or epilepsy.
  • Etiologic heterogeneity is suggested for SMR when it occurs with PDD, with distinct risk profiles observed across sex and racial groups.
  • Findings highlight the importance of considering specific diagnostic categories when examining SMR risk factors.

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