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Decreased cerebellar posterior vermis size in fragile X syndrome: correlation with neurocognitive performance
S H Mostofsky1, M M Mazzocco, G Aakalu
1Kennedy Krieger Institute, Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Abstract:
We examined whether posterior vermis size is smaller in individuals with fragile X syndrome (fra X) than in control subjects and whether this decreased size is associated with cognitive performance. Cognitive and behavioral dysfunctions have been identified in fra X; however, underlying neuropathogenic mechanisms remain unclear. MRI was used to investigate the posterior fossa in 32 males with fra X, 28 males with other causes of cognitive disability (CD), and 38 males with normal development (ND) as well as and in 37 females with fra X and 53 female control subjects. Among females with fra X, neurocognitive correlates of posterior vermis size were examined. Posterior vermis size (cross-sectional area) in males with fra X was significantly smaller compared with CD and ND groups, particularly when corrected for intracranial area. Posterior vermis size corrected for intracranial area was significantly smaller in females with fra X compared with control subjects. Compared with males with fra X and non-fra X control subjects, posterior vermis size in females with fra X was intermediate. After statistically removing the effect of mean parental IQ, posterior vermis size predicted a significant proportion of the variance (10 to 23%) of performance on full-scale, verbal, and performance IQ; block design; categories achieved on the Wisconsin Card Sorting Test; and the Rey inventory score. The size of the posterior vermis is significantly decreased in fra X, more so in males than in females. In females with fra X, posterior vermis size predicts performance on selected cognitive measures.
Insights
The posterior vermis is smaller in individuals with fragile X syndrome (fra X), particularly in males. This reduced size correlates with cognitive performance in females with fra X.
Area of Science:
- Neuroscience
- Genetics
- Developmental Biology
Background:
- Cognitive and behavioral dysfunctions are characteristic of fragile X syndrome (fra X).
- The underlying neuropathogenic mechanisms of fra X remain unclear.
- Brain structure abnormalities may contribute to fra X phenotypes.
Purpose of the Study:
- To determine if posterior vermis size is reduced in individuals with fra X compared to controls.
- To investigate the association between posterior vermis size and cognitive performance in fra X.
- To explore sex differences in posterior vermis size and its cognitive correlates in fra X.
Main Methods:
- Magnetic Resonance Imaging (MRI) was used to measure posterior vermis size (cross-sectional area).
- Participants included males and females with fra X, males with cognitive disability (CD), and normal development (ND) controls.
- Cognitive assessments included IQ tests, Wisconsin Card Sorting Test, and Rey inventory.
Main Results:
- Posterior vermis size, corrected for intracranial area, was significantly smaller in males with fra X compared to CD and ND groups.
- Females with fra X also showed a significantly smaller posterior vermis size compared to female controls.
- In females with fra X, posterior vermis size predicted variance in IQ, block design, and Wisconsin Card Sorting Test performance.
Conclusions:
- Posterior vermis size is significantly decreased in fragile X syndrome (fra X), with a more pronounced reduction in males.
- In females with fra X, reduced posterior vermis size is associated with impaired performance on specific cognitive measures.
- These findings highlight the role of the posterior vermis in the neurodevelopmental aspects of fra X.