POSITRON EMISSION TOMOGRAPHY AND NEUROPSYCHOLOGICAL CORRELATIONS IN CHILDREN WITH TURNERS-SYNDROME

A wide variety of learning and cognitive impairments have been identif ied in individuals with Turner's syndrome (TS), leading to diverse pre dictions regarding the neural substrates of TS. However, neuropatholog ical studies have failed to identify any consistent structural abnorma lity in TS. Using positron emission tomography (PET), the current stud y provided a unique opportunity to examine patterns of cerebral glucos e metabolism in girls with TS as compared to normal controls, and to e xamine 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 ch osen 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 cognitiv e or learning impairment; and for exploratory purposes, 1 with no hist ory of learning or cognitive difficulties), and 6 age-matched controls . Neuropsychological testing was also performed on the Turner girls. T he 5 girls with TS having some degree of cognitive or learning impairm ent 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 signif icance, Four Turner girls exhibited glucose metabolism at or below the 30th percentile bilaterally in the parietal and lateral occipital cor tical regions. The remaining 2 TS girls (1 with limited evidence of co gnitive impairments and 1 who was free of cognitive impairments) exhib ited normal or near-normal. glucose metabolism in these regions, Indiv idual patterns of abnormal metabolic activity corresponded well with p rofiles of learning and cognitive impairments. These findings are gene rally consistent with those reported by Clark, Klonoff, and Hayden (19 90) in suggesting that bilateral parietal and occipital lobe dysfuncti on may contribute to cognitive impairments in TS. Additionally, the pr esent study underscores the heterogeneity of TS and suggests that our finding of parietal hypometabolism should not be generalized to TS ind ividuals who are free of cognitive impairments.