Alzheimer's disease in Down's syndrome

TLDR

The study demonstrates that longitudinal neuropsychological assessments and laboratory testing can diagnose Alzheimer’s disease in severely and profoundly retarded Down’s syndrome patients after excluding other dementia causes. The authors used longitudinal neuropsychological evaluations and laboratory testing to rule out other dementia causes and diagnose AD in Down’s syndrome patients. Seven Down’s syndrome patients over 40 developed Alzheimer’s disease, with dementia lasting 2.5–9.2 years, progressive cognitive decline, and extensive amyloid plaques and neurofibrillary tangles in cortical and subcortical regions, along with small strokes in four and amyloid angiopathy in five.

Abstract

Clinical and neuropathologic evidence points to the development of Alzheimer's disease (AD) in seven Down's syndrome patients above age 40. Dementia was observed in these patients over periods of 2.5 to 9.2 years. The first clinical sign of AD, visual memory loss, was succeeded by impaired learning capacity and decreased occupational and social functioning, and culminated in seizures and urinary incontinence. The morphometric observations of the brains of these seven patients with AD showed that the numbers of plaques and tangles exceeded 20 per 1.5 X 10(6) microns2 area, in both the prefrontal and hippocampal cortices. Plaques and tangles were also evident in the basal ganglia, thalamus, hypothalamus, and midbrain. In addition, we found that four of the seven brains showed small strokes, and five of the seven amyloid angiopathy. This study also indicates that by longitudinal neuropsychological evaluations and lab tests, which exclude other causes of dementia, the diagnosis of AD can be made even in severely and profoundly retarded patients.