Positron emission tomography and neuropsychological correlations in children with turner's syndrome

Abstract

A wide variety of learning and cognitive impairments have been identified in individuals with Turner's syndrome (TS), leading to diverse predictions regarding the neural substrates of TS. However, neuropathological studies have failed to identify any consistent structural abnormality in TS. Using positron emission tomography (PET), the current study provided a unique opportunity to examine patterns of cerebral glucose metabolism in girls with TS as compared to normal controls, and to examine diverse neuropsychological profiles of individual participants in relation to anatomical sites of metabolic dysfunction as identified with PET. TS girls with a wide range of cognitive functioning were chosen for study. PET studies in the awake, resting state were performed on 6 girls (ages 11–15 years) with TS (5 with some degree of cognitive or learning impairment; and for exploratory purposes, 1 with no history of learning or cognitive difficulties), and 6 age‐matched controls. Neuropsychological testing was also performed on the Turner girls. The 5 girls with TS having some degree of cognitive or learning impairment exhibited significantly lowered parietal metabolism as compared to the control group. However, when the nonimpaired TS girl was included in these analyses, the difference between groups did not reach significance. Four Turner girls exhibited glucose metabolism at or below the 30th percentile bilaterally in the parietal and lateral occipital cortical regions. The remaining 2 TS girls (1 with limited evidence of cognitive impairments and 1 who was free of cognitive impairments) exhibited normal or near‐normal glucose metabolism in these regions. Individual patterns of abnormal metabolic activity corresponded well with profiles of learning and cognitive impairments. These findings are generally consistent with those reported by Clark, Klonoff, and Hayden (1990) in suggesting that bilateral parietal and occipital lobe dysfunction may contribute to cognitive impairments in TS. Additionally, the present study underscores the heterogeneity of TS and suggests that our finding of parietal hypometabolism should not be generalized to TS individuals who are free of cognitive impairments.