Table 3.

Instruments based on informant reports

Author (Year)	Country and setting (clinical or applied)	Test name	Ability tested	Ppts and age	Type of ID	Groups	Outcome (what was sig?) ><	Comments
Zeilinger et al. (2015) [58]	United States—applied (in large residential care homes)	The National Task Group—early detection screen for dementia [59]	Dementia Status	221 carers	ID. All participants are cared for.	Groups	Four feasibility dimensions of use of the NTG-EDSD were reported on by carers. However, data from the NTG-EDSD were not assessed directly. All feasibility dimensions were rated good to very good and 80% of the carers found the NTG-EDSD useful or very useful in the early detection of dementia.	Reliability and validity of the instrument for clinical use in aiding dementia diagnostic assessment was not assessed. Therefore, further research is needed before use of this instrument.
Lin et al. (2014) [55]	Taiwan—Setting is not clearly stated but potentially an applied setting.	Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID[60])	Dementia status	459 ppts Aged: 45+ years	ID of varying degree	Cases = Dementia Controls = Nondementia	Was used to identify cases and controls in this study. 16.3% of ppts in this study were identified as being demented based on the DSQIID.	Although originally designed for use in DS is an effective tool for diagnosing dementia in ID.
		Activities of Daily living Questionnaire (ADL [54])	Daily functioning				Disability level and comorbidity can explain 10% of the ADL score variation. Dementia conditions can only explain 3% of the ADL score variation in the study.	ADL would not be an effective tool for diagnosing dementia in ID
de Vreese et al. (2011) [61]	Italy—Applied setting	Assessment for adults with Developmental Disabilities Scale (AADS-I [61])	Behavior	63 ppts	All ID included		Good reliability and validity found.	Useful for detecting dementia if used longitudinally.
Kirk et al. (2006) [62]	UK—Setting is not clearly stated.	Dementia questionnaire for mentally retarded people (DMR)[56]	Dementia status Behavior	88 ppts Aged: 40+	Varying ID (n = 76) And DS (n = 12)	All ppts completed both tests	DMR significantly related to ABS	Would need to use both to assess an individual for dementia diagnosis as neither covers the full range of factors effected by dementia.
		The Adaptive Behaviour Scale (ABS-RC2) [43]					ABS significantly related to DMR	2 questionnaires showed significant relationships.
Shultz et al. (2004) [30]	United States—Applied setting (rooms at group homes or workshops)	The Dementia Scale for Down Syndrome (DSDS)	Dementia status	38 ppts Aged: 45–74	ID without DS (32%) and ID with DS (68%)	Cases = Dementia Controls = Non dementia	Both dementia scales discriminated between groups.	All informant reports used were able to detect cases vs controls and therefore could be informative to clinicians looking to make a decision regarding dementia diagnostics for people with ID.
		Dementia questionnaire for mentally retarded people (DMR)[56]	Dementia status				The dementia scales were not related to premorbid IQ, age, or sex.
		Reiss screen for maladaptive behavior[63]	Adaptive behaviour				Various Reiss screen subscales also discriminated between groups.
Prasher et al. (2004) [64]	UK—Setting is not clearly stated.	Adaptive Behaviour Dementia Questionnaire (ABDQ [64])	Behavior	150 ppts (83 male 67 females) Mean age: 44 years	Down syndrome	Cases = Diagnosed DAT during 5 year study Controls = remained non dementia throughout.	The scale has good reliability and validity. Overall accuracy = 92%.	First tool designed specifically for detecting DAT in DS.
Lin et al. (2014) [65]	Taiwan—Setting is not clearly stated but potentially an applied setting.	Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID—[60])	Dementia Status	196 ppts Aged: 15–48 years	Down syndrome	Younger = adolescent ppt Older = adult ppts	Older > younger on DSQIID scores. Older age (P = .001) and comorbid conditions (P = .003) were significantly associated with DSQIID scores. Age (P < .01), severe disability level (P < .05), and comorbid condition (P < .01) significantly explained 13% of variation in DSQIID scores after adjusting for sex, education level, and multiple disabilities.	DSQIID used well to diagnose dementia here in DS but need to consider other demographic factors that play a large influence on dementia status.
Ball et al. (2004) [66]	UK—Setting is not clearly stated.	Modified version of Cambridge examination for mental disorders of the elderly (CAMDEX)	General cognitive functioning	74 ppts at first visit and 56 ppts at repeat 6 years later Aged: 30+ years	Down syndrome		CAMDEX-based diagnosis of AD shown to be consistent with objectively observed cognitive decline (good concurrent validity) and to be a good predictor of future diagnosis. Inter-rater reliability was good with Kappa >0.8 for 91% of items and >0.6 for all items.	Modified CAMDEX informant interview useful when diagnosing dementia in ID and DS.
McCarron et al. (2014) [40]	Ireland & United States—Clinical Setting (Memory clinic)	Daily Living Skills Questionnaire (DLSQ) [67]	Daily Functioning	77 ppts Aged: 35+ years	Down syndrome	Cases = dementia Controls = non dementia	Over 14 year follow-up average age of diagnosis = 55.41 years (SD = 7.14). Median survival of 7 years after diagnosis. Cases older than controls (sig) Decline in DLSQ score was shown 3-4 years prior to diagnosis. Presence of dementia also associated with epilepsy and sensory impairments.	Changes in DLSQ indicated diagnosis 3–4 years apriori. More effective than direct tests used (DMSE and TSI) Also informative about variables that are associated with dementia diagnosis.
		Dementia Questionnaire for Mentally retarded people (DMR)[56]					Among instruments used DMR most sensitive to tracking change in symptoms over time before diagnosis, reporting changes 5 years prior to diagnosis. Direct tests used only reported changes 1 year prior to diagnosis.	DMR most effective at reporting changes in functioning.
Deb (2007) [60]	UK—Setting is not clearly stated.	Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID—[60])	Dementia Status	193 ppts Aged: 23–77 years Mean age = 55 years	Down syndrome		Sensitivity = 0.92 and specificity = 0.97 On DSQIID score of 20. Internal consistency (a1/4 0.91) for all its 53 items, and good test–retest and inter-rater reliability. Good construct validity was established by dividing the items into 4 factors.	Valid and reliable screening method for dementia in DS.
Kay (2003) [42]	UK—Clinical setting	Adaptive Behaviour Scale (ABS)	Behavior	87 ppts Aged: 20+ years	Down syndrome	No dementia cases participated, the sample was made up of individuals with DS only.	Significantly correlated with direct test Prudhoe cognitive functioning test (PCFT—see Table 1) ABS correlated significantly with the degree of ID.	Was able to obtain scores for all levels of ID including profound, whereas the direct test was not able to.
Deb et al. (1999) [48]	UK—Setting is not clearly stated.	Dementia Questionnaire for persons with Mentally Retardation (DMR)[56]	Dementia Status	62 ppts Aged: 35+ with DS.	Down syndrome	Cases = Dementia (n = 26) Controls = non dementia (n = 36)	DMR and DSDS showed good positive correlation. A similar positive correlation was found between the overall DSDS score and the scores in the main subcategories of the DMR. Direct test used (MMSE) could not be completed by all ppts.	Informant scales, rather than the direct tests, were more useful for the diagnosis of dementia in people with an intellectual disability.
		Dementia Scale for Down Syndrome (DSDS[68])	Dementia Status

Abbreviations: ID, intellectual disabilities; DS, Down syndrome; DAT, dementia Alzheimer's type; ppts, participants.

NOTE. Tests highlighted in bold indicate repeated use within studies. Age is denoted in years.