Magnetic resonance imaging, Down's syndrome and Alzheimer's disease: research and clinical implications

Abstract

Background The diagnosis of Alzheimer's disease (AD) remains at times difficult to make using available neuropsychological measures. Neuro-imaging is a relatively new form of detecting the changes associated with dementia. The present study investigated the role of magnetic resonance imaging (MRI) in diagnosing AD in adults with Down's syndrome (DS). Methods Subjects with DS and Alzheimer-type dementia were matched to non-demented controls with DS. Magnetic resonance imaging findings (i.e. volumetric and two-dimensional scans) were compared between the two groups in order to show a relationship between the changes of AD and structural MRI abnormalities. Results Specific structural abnormalities which are seen in non-intellectually disabled subjects with dementia are also found in individuals with both DS and AD. However, such findings cannot be used to diagnose clinical AD with good accuracy in adults with DS. A number of practical issues of patient compliance and over-sedation are demonstrated by the findings.

Down Syndrome - Onset Age of Dementia

“…These long-term longitudinal observations do dispute the prevailing understanding that neuropathology [8,9] occurring concomitantly with a prodromal or asymptomatic phase precedes clinical dementia [4,10,11]. It can be speculated here whether the lack of this kind of long-term clinical data and/or the varying clinical follow-up methods utilized in different countries could explain this evident discrepancy between our results and the findings published by the others.…”

“…According to the literature AD neuropathology is observable in virtually all individuals by the age of 40 years [8,9], after which there is generally thought to be a prodromal or asymptomatic phase when AD pathology progressively accumulates so that clinical dementia is usually recognized within an age range of 48 to 56 years [10,11]. However, the results from our recent paper with 27 years follow-up of 45 adults with DS suggested that the turning point in the course of adaptive skills occurs already at the age of 35 [12].…”

Diagnosing Dementia in Adults with Down’s Syndrome

“…Claustrophobia is a significant problem with MRI scanners and general anesthesia may be required. The whole brain volume, as well as cerebral cortex, temporal lobes and cerebellum volumes are reported to be significantly smaller in individuals with DS and dementia [35][36][37]. The ventricles are significantly larger.…”

Avances Citogenéticos y Neurobiológicos en el Síndrome de Down

“…The lower volume on temporal cortical and subcortical regions (amygdala, hippocampus and temporal lobe) with verbal comprehension difficulties, memory and larger deficit presented in purely perceptual processing aspects such as color and shape (Krasuski, Alexander, Horwitz, Rapoport & Schapiro, 2002; White et al, 2003). The reduction in these regions and in the corpus callosum, coupled with the onset of the characteristic lesions of Alzheimer's disease, has also been related with the progressive deterioration of episodic memory and the subsequent onset of clinical signs of this dementia observed with advancing age (Prasher et al, 2003;Teipel et al, 2003). Similarly, the fact that most of the subcortical structures and, above all, the posterior cortical areas (parietal and occipital lobe) are not morphologically altered has been linked with better performance on tasks of visuospatial processing and visual motor coordination (Krasuski et al, 2002;.…”