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The researchers
set out to further examine reports of cognitive dysfunction in adults
with childhood-onset growth hormone deficiency (GHD) and to
investigate potential causes in atypical brain metabolism. Eleven
adults (7 male and 4 female) with childhood-onset GHD, who had been
treated with GH during childhood for 4 to 16 years (mean duration 8.2
years), were evaluated by neuropsychological testing and magnetic
resonance spectroscopy (MRS) at least 3 months after discontinuation
of GH replacement. The GHD participants were compared to a health-
and demographically-matched control group (n=9). MRS was used to
assess brain N-acetylaspartate (NAA) and NAA/choline ratios,
indices of hormonal density and integrity. The GHD group exhibited
significantly lower performance on a delayed memory recall task
(15-word delayed recall score), a measure of planning behavior,
cognitive processing speed, and attention (Trail-making test, Part
A). The GHD group also showed significantly lower NAA and NAA/choline
levels, and increased choline levels compared to controls. Finally,
IGF-I was significantly correlated with NAA levels, but not with
choline levels or NAA/choline ratios. The investigators interpret
their findings as corroboration of other reports indicating subtle
neurocognitive deficits in adults with childhood-onset GHD. Moreover,
these effects (in combination with evidence of reduced NAA level in
the brain) resemble those observed in normal aging.
van
Dam PS, de Winter CF, de Vries R, et al. Psychoneuroendocrinology.
2005;30:357–363.
Editor’s
Comment: Cognitive function in children and adults with
childhood-onset GHD has been the topic of multiple studies.
Neuropsychological testing corroborates clinical impressions that
associations between GHD and deficits in cognitive performance are
subtle; the report by van Dam et al demonstrates an altered brain
metabolism while they were off GH treatment. Nevertheless, there is
evidence that GHD, which can be a consequence of perinatal insult,
cancer (and its treatment), and other pathologic states, may be
associated with substantially increased rates of learning
disabilities.1
Future
studies of this topic will benefit from larger sample sizes and
statistical analyses that adjust for gender, participant’s
global intelligence, and adequacy of hormone replacement in adulthood
for those with multiple pituitary hormone deficits. Presently, the
benefits of GH replacement in adulthood on cognitive performance
remain unclear. Whereas, physiologic doses of GH in individuals with
adult-onset GHD appear to be ineffective,2 more promising
findings derive from a study in childhood-onset GHD.3
David E. Sandberg, PhD
References - (linked to )
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Sandberg
DE, Ognibene TC, Brook AE, Barrick C, Shine B, Grunder W. Children’s
Health Care. 1998;27:265−282.
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Baum
HB, Katznelson L, Sherman JC, et al. J Clin Endocrinol Metab.
1998;83:3184−3189.
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Deijen JB, de Boer
H, van der Veen EA. Psychoneuroendocrinology. 1998;23:45−55.
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