Difficulties of diagnosing and managing dementia in people with Down syndrome

As practising clinicians who provide care to adults with Down syndrome, we appreciate Eady and colleagues’ attempt to address a real concern in this patient population.¹ However, we have significant concerns about clinicians potentially using in their practice the conclusions drawn by the authors. The study conclusions offer false hope and may result in wasted resources.

The authors themselves state that the treated and untreated groups have significant differences that would favour the treated group: ‘There were significant baseline differences between the groups prescribed and not prescribed antidementia medication. Those who were not prescribed medication were older, more likely to have severe–profound intellectual disability, and had more severe dementia symptoms at baseline’. Given those differences, it is difficult to understand how the authors can come to the conclusion that treatment with antidementia medications is of benefit.

Also of concern is the question of what the clinical significance would be from a functional perspective. Dementia takes a tremendous toll on the caregivers and families. Even if the medications do extend life, where is the benefit? What kind of life will they have? We believe quality of life would have been a more useful measured outcome.

Furthermore, there are four published studies and Cochrane reviews that show no benefit with donepezil,² rivastigmine,³ memantine,^{4, 5} or galantamine.⁶ Another Cochrane Review in 2015 showed no benefit of pharmacological interventions for cognitive decline in people with Down syndrome.⁷

In our experience as the directors of Down syndrome clinics for adults, the big issue is really how the diagnosis of dementia is made. Clinicians tend to easily apply the diagnosis of Alzheimer's dementia without looking at all the potential causes of pseudodementia in this population.⁸ They often assume that loss of ability is as a result of dementia because of a study published in 1985 that showed plaques and tangles in the brain tissue of all people with Down syndrome over the age of 35.⁹ Wisniewski & Rabe subsequently wrote that there was a discrepancy between neuropathology and the occurrence of dementia in people with Down syndrome.¹⁰ Just as in the population of typically developed older adults, the diagnosis of Alzheimer's dementia in people with Down syndrome should be made only after evaluation for causes of pseudodementia.