Diagnosis of dementia in individuals with intellectual disability*

Abstract

The foremost impediment to progress in the understanding and treatment of dementia in adults with intellectual disability is the lack of standardized criteria and diagnostic procedures. Standardized criteria for the diagnosis of dementia in individuals with intellectual disability are proposed, and their application is discussed. In addition, procedures for determining whether or not criteria are met in individual cases are outlined. It is the intention of the authors, who were participants of an International Colloquium on Alzheimer Disease and Mental Retardation, that these criteria be appropriate for use by both clinicians and researchers. Their use will improve communication among clinicians and researchers, and will allow researchers to test hypotheses concerning discrepancies in findings among research groups (e.g. dementia prevalence ranges and age of onset).

A four year prospective study of age-related cognitive change in adults with Down's syndrome

“…However, it should be noted that the majority of participants (71n7 %) experienced no cognitive deterioration. These estimates of cognitive deterioration are high in comparison to the range described by Aylward et al (1995) and those given by Lai & Williams (1989). This may be because the criteria employed in this study are not diagnostic for dementia but are operationalized in terms of cognitive impairment.…”

“…Prevalence rates of dementia increased with age in the 53 people living in an institutional setting, from 8 % in the 35-49 age group to 75 % in those over 60 years. In a review of prevalence estimates, Aylward et al (1995) document prevalence rates of dementia in DS to vary from a few percent for adults between 30-39 years of age, 10 % to 25 % in those aged between 40-49 years, 20 % to 50 % in those 50-59 years of age and between 30 % and 75 % in those above 60 years of age. This overview of prevalence is in contrast to the findings of Burt et al (1995) and Devenny et al (1996).…”

Neuroimaging of individuals with Down’s syndrome at-risk for dementia: Evidence for possible compensatory events

“…The diagnosis of dementia in people with DS is exceedingly difficult because clinical and behavioral measures like the Mini Mental Status Examination (MMSE) are confounded by low intelligence (Aylward, Burt et al 1997;Deb and Braganza 1999). For this study where a main goal is to identify brain changes associated with the earliest indicators of dementia, before a clinical diagnosis is possible, we had an even more difficult problem.…”

Chapter 4 Alzheimer's Disease in Adults with Down Syndrome

“…Measures were focused on those that were likely to be sensitive to changes associated with developmental aging and dementia, and/or could be useful in describing profiles of changes that differentiated between these two very different situations. In making selections of procedures, maximizing compatibility with recommendations published by a Working Group focused on assessment of dementia within the population with intellectual disability was desired (Aylward, Burt, Thorpe, Lai, & Dalton, 1997;Burt & Aylward, 2000). Direct participant testing had to be sufficiently brief and had to incorporate frequent breaks in order to avoid fatigue and avoid approaching the limits of attention span, both of which could exert strong effects on performance.…”

“…In adults with Down syndrome, this pathology is superimposed on a neural substrate already affected by pre-existing developmental abnormalities. Therefore, as dementia must be assessed against a baseline of lifelong intellectual disabilities (Aylward et al, 1997), neuropathology must be assessed against neurodevelopmental abnormalities that include defects of neurogenesis, synaptogenesis and lamination producing reductions in the sizes of specific brain structures (Crome, 1972;Raz et al, 1995), and a reduced number of neurons and synapses (Ross, Galaburda, & Kemper, 1984;Wisniewski, 1990).…”