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Brain Structure and Cognitive Deficits in Klinefelter’s Syndrome« Back to Volume 22, Issue 3, September 2006 - Table of Contents Noting research demonstrating cognitive deficits in adults with Klinefelter’s syndrome (KS), Itti and colleagues assessed brain morphometry in 18 men with KS (18 to 63 years of age) compared with 20 age-matched control participants. Participants with KS were recruited from a cohort of individuals followed for management of hypogonadism; 10 of whom were receiving testosterone replacement. The KS and control participants were administered a neuropsychological battery that assessed verbal and nonverbal domains and had an MRI to ascertain brain volumes of interest (VOI). Demographic variables, neuropsychological scores, and VOIs between KS and controls were then compared. Replicating established findings, KS patients performed significantly poorer than controls on language-related tasks associated with processing speed and executive function. Compared with control participants, KS patients showed significantly enlarged ventricular volume and reduced bilateral cerebellar hemispheres. Additionally, compared with right-handed controls, cerebrospinal fluid-corrected VOIs confirmed reduced cerebellar hemispheres in right-handed KS patients as well as significantly reduced left temporal lobe volume. No differences were found between patients who were or were not treated with testosterone. Several significant correlations between neuropsychological test scores and abnormal MRI volumes were found: ventricular volume was inversely correlated with verbal processing speed, verbal executive function, and nonverbal processing speed; left temporal lobe volume was positively correlated with language scores and verbal processing in right-handed patients. Given this pattern of results, Itti and colleagues concluded that the supernumerary X chromosome and/or congenital hypogonadism caused structural alternations in subcortical pathways involved in language processing – they interpreted results to support the existence of a neurobiological substrate for cognitive deficits observed in those with KS. Editor’s CommentIn August of 2000, the NIH sponsored a meeting (co-sponsored by the March of Dimes and Klinefelter Syndrome and Associates) to address gaps in understanding of Klinefelter’s syndrome.1,2 At that time, correlative studies of neurocognitive function and brain morphometry were in their beginnings. This study represents significant progress in this line of research. A caveat regarding generalization of the findings to the total KS population pertains to ascertainment of this particular sample. Although KS participants were recruited from a population followed for management of hypogonadism (and not based on behavioral or cognitive characteristics), the proportion of prenatally-diagnosed versus postnatally-diagnosed subjects was not reported. This distinction is relevant in view of the observation that the prenatal population is less affected developmentally and is more academically successful than individuals with KS identified through postnatal diagnosis.3 Although the sample was too small to partition according to diagnosis timing, this information would be valuable in gauging how representative these findings are of individuals with KS. Strengths of the research design included control of participant handedness — a variable contributing to the pattern of findings. Importantly, the investigators also examined the relationship between testosterone supplementation, neuropsychological performance and MRI volumes: associations were not generally detected. In contrast to the exciting developments in our understanding of the neurological underpinnings of KS-characteristic cognitive and language deficits, there is a dearth of research on remediation strategies. In this sense, research priorities in KS parallel those in Turner syndrome; in both conditions the focus on biological underpinnings of neurocognitive deficits is virtually exclusive. David E. Sandberg, PhD References - (linked to
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Volume 24 Number 1
May 2008
www.GGHjournal.com
ISSN 1932-9032
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