Subjects With Intellectual Disability and Familial Need for Full-Time Special Education Show Regional Brain Alterations: A Voxel-Based Morphometry Study

Abstract

Subjects attending full-time special education (SE) often have multifactorial background for their cognitive impairment, and brain MRI may show nonspecific changes. As voxel-based morphometry reveals regional volume differences, we applied this method to 119 subjects with cognitive impairments and familial need for full-time SE-graded into three levels from specific disorders of cognitive processes (level 1) to intellectual disability (IQ Ͻ70; level 3)-and to 43 age-matched controls attending mainstream education (level 0). Subjects in SE groups had smaller global brain white matter (WM), cerebrospinal fluid, and total brain volume than controls. Compared with controls, subjects with intellectual disabilities in SE level 3 showed greater regional gray matter volumes bilaterally in the ventral and dorsal anterior cingulate cortex and smaller regional gray matter volumes in the left thalamus and cerebellar hemisphere. Further, they had greater WM volume in the left frontoparietal region and smaller WM volumes in the posterior limbs of the internal capsules. Subjects in SE level 1 and 2 groups showed the same tendency, but the results were nonsignificant. In conclusion, compared with controls, subjects with intellectual disabilities showed in voxel-based morphometry analysis several regional brain alterations. In developed countries, approximately one of every five school-aged children needs special education (SE) of some type, and the need for full-time SE is ϳ8% (1,2). Epidemiologic studies indicate that the etiology of intellectual disability (ID) (ICD-10 codes F70 -F79) is unexplained or multifactorial in approximately half of the cases (3), a number even higher among children with specific disorders of cognitive processes (DCP). In MRI examinations, ventricular enlargements, subtle callosal abnormalities, cerebral cortical anomalies, white matter (WM) signal intensity abnormalities, and mild cerebellar fissure enlargements typically appear in subjects with ID (4 -7). These findings have been designated as neuroimaging markers frequently associated with ID (5). Nevertheless, children and adolescents with IDs of unexplained etiology often have brain MRIs considered normal or that reveal only minor abnormalities (5).Voxel-based morphometry (VBM) is a fully automatic method for assessing changes throughout the brain by analyzing local volume differences (8). In children and adolescents with cognitive deficits, many reports applying VBM exist (9 -14). However, to our knowledge, only one VBM study to date has investigated children and adolescents with IDs of unexplained etiology (15). Compared with controls, these subjects had smaller global WM and total brain volumes and also showed several local gray matter (GM) and WM volume differences in both the cerebrum and the cerebellum (15). In intellectually intact children and adolescents, volumetric MRI studies with VBM have demonstrated a positive correlation between global GM volume and general intelligence and positive correlations between intelligence and...

Brain development and scholastic achievement in the Education Quality Measurement System tests in Chilean school-aged children

“…Furthermore, educational selectivity correlates with HC and not with weight and height (21). Findings from other authors confirm that students with intellectual disabilities had smaller total BVs (24).…”

The role of the thalamus in neuro-cognitive dysfunction in early unilateral hemispheric injury: A multimodality imaging study of children with Sturge–Weber syndrome

“…Therefore, it is not surprising that even isolated damage of the thalamus may result in cognitive dysfunction 38. Studies investigating the potential neuroanatomical substrates of cognitive impairment from various causes demonstrated abnormalities of the thalamus 8–11. Recent neuroimaging and EEG data also supported the participation of the thalamus in the network responsible for cognitive performance 39, 40.…”

“…Thalamic magnetic resonance imaging (MRI) and PET abnormalities have been commonly observed in intellectually disabled patients due to different pathophysiologic origins 8–11. Therefore, it can be hypothesized that thalamic abnormalities may be a marker of abnormal neuro-cognitive functions in children with SWS.…”

The GABRB1 gene is associated with thalamus volume and modulates the association between thalamus volume and intelligence

“…Bjuland et al (2014) further found that, among all subcortical volumes, thalamus volume had the highest positive correlation with intelligence measured by Wechsler Adult Intelligence Scales in young adults born preterm with very low birth weight. Subjects with intellectual disabilities (IQ b 70) also showed smaller left thalamus than did normal controls (Mannerkoski et al, 2009). In addition, reduced thalamus volume was found to be correlated with various poor intellectual performance in patients with alcohol-dependence, schizophrenia, complex partial seizures, sickle cell anemia, tuberous sclerosis complex, and periventricular leukomalacia (Chanraud et al, 2007;Coscia et al, 2009;Lin et al, 2013;Mackin et al, 2014;Ridler et al, 2007;Zubiaurre-Elorza et al, 2012).…”