Background and purpose: Down syndrome (DS) is the most common genetic cause of mental retardation with deficits in language and memory. Mental retardation of varying degrees is the most consistent feature of DS. The objective of this study was to use high-resolution magnetic resonance imaging (MRI) techniques to investigate the volumes of the hippocampus, amygdala, and temporal and frontal lobes in children with DS compared with healthy children.
Material and methods: MRI of 49 patients was reviewed prospectively. The study included 23 children with DS (9 girls and 14 boys, mean age 6.7 ± 3.7 years) and 26 healthy children (11 girls and 15 boys, mean age 8.3 ± 2.4 years). Volumes of the right and left hippocampus, the right and left amygdala, temporal and frontal lobes and the total brain volume were measured by a radiologist who was unaware of the diagnosis.
Results: Total brain volume in children with DS was significantly lower compared with controls. It was associated with significantly lower volume of the frontal and temporal lobes. Children with DS had a significantly smaller right and left hippocampus volume and a significantly smaller right and left amygdala volume than did the control group. We also found a negative correlation between mental retardation and volume of the right hippocampus.
Conclusions: The presence of these abnormalities from an early age contributes to the specific cognitive and developmental deficits seen in children with DS.