Comment

A population perspective on the IWG-2 research diagnostic criteria for Alzheimer's disease

La démence est un syndrome qui se définit par un trouble de la mémoire accompagné par un déficit dans au moins un autre domaine cognitif (i.e., l’aphasie, l’apraxie, l’agnosie ou une atteinte des fonctions exécutives). L’âge est le principal facteur de risque de démence ; parmi les autres facteurs de risque on compte les facteurs cardiovasculaires, les comportements de santé et les facteurs psychosociaux tels que l’éducation. Cependant, ce domaine de recherche se caractérise par des résultats incohérents et l’échec des essais cliniques. Cet article tente d’apporter une explication à ces incohérences en soulignant la longue période d’incubation de la démence et propose un cadre pour la recherche dans ce domaine.

Dementia is a syndrome that is characterized by memory loss, accompanied by a deficit in at least one other cognitive domain (i.e., aphasia, apraxia, agnosia or impairment of executive function). Age is the principal risk factor for dementia ; other risk factors include cardiovascular factors, health behaviours, and psychosocial factors such as education. However, this area of research is characterized by inconsistent findings and failed clinical trials. This article attempts to provide an explanation for these inconsistencies by highlighting the long incubation period of dementia and propose a framework for research.

The importance of home research study visit capacity in Alzheimer's disease (AD) studies is unknown.

All evaluations are from the prospective Adult Changes in Thought study. Based on analyses of factors associated with volunteering for a new in-clinic initiative, we analyzed AD risk factors and the relevance of neuropathologic findings for dementia comparing all data including home visits, and in-clinic data only. We performed bootstrapping to determine whether differences were greater than expected by chance.

Of the 1781 people enrolled during 1994–1996 with ≥1 follow-up, 1369 (77%) had in-clinic data, covering 61% of follow-up time. In-clinic data resulted in excluding 76% of incident dementia and AD cases. AD risk factors and the relevance of neuropathologic findings for dementia were both different with in-clinic data.

Limiting data collection in AD studies to research clinics alone likely reduces power and also can lead to erroneous inferences.