Alzheimer dementia in Down's syndrome: the relevance of cognitive ability

Abstract

More years of education have been found to be associated with a lower rate of Alzheimer disease (AD) in individuals without intellectual disability. It has been proposed that education reflects greater ‘synaptic reserve’ and that greater synaptic reserve may defer the development of AD. The present study compared individuals with Down's syndrome (DS) who were found to have symptoms of dementia with those who remained symptom‐free to determine if the two groups differed in their level of education, employment, recreational activities, years in an institution or overall level of cognitive functioning. Thirty‐five adults with DS aged between 29 and 67 years were assessed. The participants were recruited from a community health facility and included individuals with a wide range of ability levels. Neuropsychological testing, caregiver report and the Dementia Scale for Down Syndrome (Gedye 1995) were used to identify decline in participants over periods of 6 months to 3 years. After the effect of age was statistically removed, multiple regression analyses revealed that level of cognitive functioning was significantly associated with decline such that a higher level of cognitive functioning predicted less decline. None of the environmental variables (i.e. educational level, years in an institution and employment) were directly associated with decline; however, a post hoc regression using level of cognitive functioning as the outcome variable revealed that level of cognitive functioning itself was associated with these environmental variables. A higher level of cognitive functioning was associated with fewer cases of dementia in individuals with DS, and level of cognitive functioning appears to be associated with environmental factors such as level of education, years in an institution and employment. The present findings suggest that environmental interventions aimed at improving level of cognitive functioning may also be useful in deferring the onset of dementia.

Down's syndrome and dementia

“…Safety and stability of the individual's environment are of the utmost importance. It has been shown that the level of cognitive function has the greatest association with decline and that, in turn, environmental factors have the greatest impact on cognitive function (Temple et al, 2001). It might therefore hold true that environmental interventions increase cognitive function, which in turn might ameliorate the progression of the dementia.…”

“…The rate of deterioration appears to increase with age (Oliver et al, 1998). The level of pre-existing cognitive function is also closely associated with the rate of decline (Temple et al, 2001). …”

Síndrome de Down y enfermedad de Alzheimer: factores de riesgo, evaluación e intervención

“…En las personas con SD, un nivel alto de funcionamiento cognitivo se asocia con un menor número de casos de demencia, por lo que se espera que personas con niveles cognitivos más bajos experimenten síntomas de forma temprana y un declive más rápido (Temple et al, 2001). Además, pueden desarrollar EA más pronto que otras personas debido a su producción aumentada de ßA y a su menor reserva cognitiva, pudiendo ésta ser el resultado de la combinación de la discapacidad intelectual pre-existente y de factores genéticos tales como la concentración de ßA y myo-inositol (mI) en el cerebro (Mullins et al, 2013).…”

“…Además, pueden desarrollar EA más pronto que otras personas debido a su producción aumentada de ßA y a su menor reserva cognitiva, pudiendo ésta ser el resultado de la combinación de la discapacidad intelectual pre-existente y de factores genéticos tales como la concentración de ßA y myo-inositol (mI) en el cerebro (Mullins et al, 2013). En este sentido, el nivel de funcionamiento cognitivo parece estar asociado con factores ambientales tales como el nivel de educación, años en una institución y el tipo de empleo (Temple et al, 2001). …”

Telomere Shortening in Down Syndrome Patients—When Does It Start?

“…Standardized criteria for the diagnosis of dementia in DS include both informant-based and direct measures (O'Caoimh and Clune, 2013). The severity of preexisting cognitive impairment may also be a predictor of the rate of cognitive deterioration in DS (Temple et al, 2001). However, determining whether it is a cause or a consequence is not clear yet.…”