MRI volumes of the hippocampus and amygdala in adults with Down's syndrome with and without dementia.

OBJECTIVE: This study sought to determine whether volumes of the hippocampus and amygdala are disproportionately smaller in subjects with Down's syndrome than in normal comparison subjects and whether volume reduction is greater in Down's syndrome subjects with dementia. METHOD: The subjects were 25 adults with Down's syndrome (eight with dementia) and 25 cognitively normal adults who were individually matched on age, sex, and race. Magnetic resonance imaging measures included volumes of the hippocampus, amygdala, and total brain. Nineteen of the Down's syndrome subjects had follow-up scans (interscan interval = 9-41 months). RESULTS: Nondemented Down's syndrome subjects had significantly smaller volumes of the hippocampus, but not the amygdala, than their comparison subjects, even when total brain volume was controlled for. Volumes of both the hippocampus and the amygdala were smaller in the demented Down's syndrome subjects than in their comparison subjects, even when total brain volume was controlled for. Age was not correlated with volume of the hippocampus or amygdala among the nondemented Down's syndrome subjects and the comparison subjects; age was correlated with volume of the amygdala, but not the hippocampus, among the Down's syndrome subjects with dementia. Changes in volume over time were not statistically significant for either the demented or the nondemented subjects. CONCLUSIONS: Hippocampal volume, while disproportionately small for brain size in individuals with Down's syndrome, remains fairly constant through the fifth decade of life in those without dementia. All subjects over age 50 who had Down's syndrome demonstrated volume reduction in the hippocampus as well as clinical signs of dementia. Dementia was also associated with volume reductions in the amygdala that exceeded reductions in total brain volume.

Basal ganglia volume in adults with Down syndrome.

This study was designed to determine the effects of aging on the volume of the basal ganglia in individuals with Down syndrome (DS) and to examine the relationship between basal ganglia volumes, neuropsychological test performance, and dementia status in this population. Subjects were 32 adults with DS. Basal ganglia volumes from 22 of these subjects were compared with those of 22 cognitively-normal individuals, who were individually matched on age, sex, and race. Performance on neuropsychological tests was correlated with basal ganglia volumes for 32 individuals with DS, and basal ganglia volumes of five demented DS subjects were compared with those of 14 non-demented DS subjects. Results indicated larger putamen volumes in the DS subjects, despite significantly smaller total brain volumes. Volumes of caudate and globus pallidus did not differ between DS and control subjects. Although there were some significant correlations between basal ganglia volumes and age, neuropsychological test performance, and dementia status in the DS subjects, these associations appeared to be a reflection of neurodevelopmental or atrophic reductions in overall brain volume rather than a reflection of specific basal ganglia abnormality. Correlations between age and volumes of basal ganglia and total brain were not significantly greater in non-demented DS subjects than in control subjects. Results suggest that volume reductions of the basal ganglia are not a salient feature of aging or of the dementia associated with DS.

Cerebellar volume in adults with Down syndrome.

OBJECTIVES: To determine the effects of aging on cerebellar volume in individuals with Down syndrome (DS). To determine whether volume of cerebellum is associated with dementia or with age-related decline in fine-motor control. DESIGN: Case-control study involving comparison of cerebellar volumes in adults with DS and matched control subjects; survey study involving correlations between cerebellar volume and subjects' age and performance on a test of fine motor control; and longitudinal study assessing change in cerebellar volume in adults with DS. SETTING: The Johns Hopkins University School of Medicine, Baltimore, Md. PATIENTS AND OTHER PARTICIPANTS: Subjects included 40 adults with DS. Thirty of them were matched on age, sex, and race with cognitively normal subjects. A diagnosis of probable dementia was made for 5 of the subjects with DS. Longitudinal data were available for 23 of the 40 subjects with DS, with a mean interscan interval of 2 years. MAIN OUTCOME MEASURES: Volumes of cerebellum, total brain, and intracranial region were measured on magnetic resonance imaging scans. The Purdue Pegboard, a test of fine-motor control, was administered to 38 of the subjects with DS. RESULTS: Subjects with DS had significantly smaller cerebellar volumes than matched controls, even after adjusting for total brain volume or total intracranial volume. Volume of cerebellum did not correlate significantly with age for either the subjects with DS or controls. Longitudinal change in cerebellar volume in subjects with DS was not significant. Volume of total brain, but not cerebellum, correlated significantly with performance on the Purdue Pegboard. CONCLUSIONS: Although cerebellar volumes are disproportionately small in individuals with DS, they do not diminish significantly with age and do not undergo age-related atrophy that is different from that of normal controls. Volume reduction in the cerebellum does not appear to be specifically responsible for the age-related decline in fine-motor control that is observed in adults with DS.

Asymmetry of the planum temporale: methodological considerations and clinical associations.

Asymmetry of the planum temporale, a region on the posterosuperior surface of the temporal lobe involved in the production and comprehension of language, is a notable feature of the normal human brain. Several attempts have been made to measure it using both post-mortem and magnetic resonance imaging (MRI) methods, but previous approaches made inadequate allowance for the convoluted nature of the structure. The current study used rigorous criteria to define the planum and examined three separate approaches for its measurement on MRI scans. A method involving triangulation of the surface consistently gave larger values for the surface area of the planum, suggesting that this method takes account of the convoluted nature of the structure.