Article

Longitudinal studies that have examined cognitive performance in children
with intellectual disability more than twice over the course of their development
are scarce. We assessed population and individual stability of cognitive
performance in a clinical sample of children with borderline to mild
non-syndromic intellectual disability. METHOD: Thirty-six children (28 males,
eight females; age range 3-19y) with borderline to mild intellectual disability
(Full-scale IQ [FSIQ] 50-85) of unknown origin were examined in a retrospective
clinical case series using linear mixed models including at least three
assessments with standardized intelligence tests. RESULTS: Average cognitive
performance remained remarkably stable over time (high population stability, drop
of only 0.38 IQ points per year, standard error=0.39, p=0.325) whereas individual
stability was at best moderate (intraclass correlation of 0.58), indicating that
about 60% of the residual variation in FSIQ scores can be attributed to
between-child variability. Neither sex nor socio-economic status had a
statistically significant impact on FSIQ. INTERPRETATION: Although intellectual
disability during childhood is a relatively stable phenomenon, individual
stability of IQ is only moderate, likely to be caused by test-to-test reliability
(e.g. level of child's cooperation, motivation, and attention). Therefore,
clinical decisions and predictions should not rely on single IQ assessments, but
should also consider adaptive functioning and previous developmental history.
CI - (c) 2014 Mac Keith Press.

Langue : ANGLAIS