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BACKGROUND: People with Down's syndrome (DS) are at high risk for developing dementia in middle age. The biological basis for this is unknown. It has been proposed that non-demented adults with DS may undergo accelerated brain ageing. METHOD: We used volumetric magnetic resonance imaging (MRI) and manual tracing to compare brain anatomy and ageing in 39 non-demented adults with DS and 42 healthy controls. RESULTS: Individuals with DS had significant differences in brain anatomy. Furthermore, individuals with DS had a significantly greater age-related reduction in volume of frontal, temporal and parietal lobes, and a significantly greater age-related increase in volume of peripheral cerebrospinal fluid (CSF). CONCLUSIONS: Non-demented adults with DS have differences in brain anatomy and 'accelerated' ageing of some brain regions. This may increase their risk for age-related cognitive decline and Alzheimer's disease (AD). [ABSTRACT FROM AUTHOR]

Objective: The neural basis for autistic spectrum disorders is unclear, but abnormalities in the development of limbic areas and of glutamate have been suggested. Proton magnetic resonance spectroscopy ((1)H-MRS) can be used to measure the concentration of brain metabolites. However, the concentration of glutamate/glutamine in brain regions implicated in autistic spectrum disorders has not yet been examined in vivo.Method: The authors used (1)H-MRS to investigate the neuronal integrity of the amygdala-hippocampal complex and a parietal control region in adults with autistic spectrum disorders and healthy subjects.Results: People with autistic spectrum disorders had a significantly higher concentration of glutamate/glutamine and creatine/phosphocreatine in the amygdala-hippocampal region but not in the parietal region.Conclusions: Abnormalities in glutamate/glutamine may partially underpin the pathophysiology of autistic spectrum disorders, and the authors confirm earlier reports that limbic areas are metabolically aberrant in these disorders. [ABSTRACT FROM AUTHOR]

Objective: The cause of autistic spectrum disorder (i.e., autism and Asperger's syndrome) is unknown. The serotonergic (5-HT) system may be especially implicated. However, cortical 5-HT2A receptor density in adults with the disorder has not been examined, to the authors' knowledge.Method: The authors investigated cortical 5-HT2A receptor binding in eight adults with Asperger's syndrome and in 10 healthy comparison subjects with single photon emission computed tomography and the selective 5-HT2A receptor ligand 123I iodinated 4-amino-N-[1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methoxybenzamide (123I-5-I-R91150).Results: People with Asperger's syndrome had a significant reduction in cortical 5-HT2A receptor binding in the total, anterior, and posterior cingulate; bilaterally in the frontal and superior temporal lobes; and in the left parietal lobe. Also, reduced receptor binding was significantly related to abnormal social communication.Conclusions: The authors' findings suggest that adults with Asperger's syndrome have abnormalities in cortical 5-HT2A receptor density and that this deficit may underlie some clinical symptoms. [ABSTRACT FROM AUTHOR]