Screening for dementia in Down syndrome using the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE)

Abstract

AbstractBackgroundDown syndrome (DS) is genetically associated with Alzheimer´s disease (AD), and the neuropathological features of AD can be found in DS brains since early adulthood. Screening tests are required for the clinical assessment of dementia; however, the presence of intellectual disability at various degrees precludes the use of most of the available cognitive screening tests in this population, and few instruments have so far been validated for this purpose. The aim of the present study was to examine the psychometric properties of the IQCODE for the screening for cognitive/functional decline and dementia in DS.Method92 aging adults with DS (mean age 43.45 SD 8.51; 61.0% males) were enrolled for a cross‐sectional assessment by two independent psychiatrists. Inclusion criteria were: diagnosis of DS according to the International Classification of Diseases, tenth edition (ICD‐10); minimum age of 30 years; and having an informant with daily contact with the subject for the past 10 years at least. Participants were assessed by the Cambridge Examination for Mental Disorders of Older People with Down syndrome and others with Intellectual Disability (CAMDEX‐DS) using a validated Brazilian version, and by the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). The concurrent validity of the IQCODE was analyzed in relation to the gold standard CAMDEX‐DS diagnosis.ResultParticipants were allocated into three diagnostic groups according to the CAMDEX‐DS: 1‐ dementia (N= 13); 2‐ prodromal dementia (N=17); and 3‐ stable cognition (N=62). ROC curve analyses were carried out to determine the diagnostic accuracy of the IQCODE in comparison to CAMDEX‐DS by diagnostic pairs indicated that the IQCODE optimal cut‐off scores for each diagnostic pair were as follows: (a) AD versus stable cognition: 3.14 (AUC=0.993; sensitivity: 100% specificity: 96.8%; (b) AD + prodromal versus stable cognition: 3.11 (AUC=0.975; sensitivity: 93.3%; specificity: 91.9%).ConclusionThe IQCODE appears to be a suitable tool for the brief screening of cognitive/functional decline in aging DS adults.