RESUMO
BACKGROUND: People with Down's syndrome (DS) are at high risk of developing Alzheimer dementia (DS-AD) due to a triplication of the amyloid precursor protein gene. While several tools to diagnose and screen for DS-AD, such as the dementia screening questionnaire for individuals with intellectual disabilities (DSQIID), are available in English, validated German versions of such instruments are scarce. METHODS: A German version of the DSQIID questionnaire (DSQIID-G) was completed by caregivers before attending our specialist outpatient department for DS-AD. All participants were assessed blind to DSQIID-G scoring using clinical and neuropsychological examinations, including the Cambridge Examination for Mental Disorders of Older People with Down's Syndrome and Others with Intellectual Disabilities (CAMDEX-DS). ICD-10 and amyloid/tau/neurodegeneration (A/T/N) criteria were applied to detect and categorise cognitive decline. RESULTS: Of 86 participants, 43 (50%) showed evidence of cognitive decline. A definite diagnosis of DS-AD was reached in 17 (19.8%) and mild cognitive impairment in seven (8.3%) participants. Secondary causes of cognitive decline were determined among 13 (15.1%) participants, and in six (7%) cases, the diagnosis remained unclassifiable due to co-morbidities. Compared with cognitively stable individuals, participants with cognitive decline (n = 43) displayed higher DSQIID-G total scores [median (range): 3 (0-21) vs. 19 (0-48), P < 0.001]. A total score of >7 provided a sensitivity of 0.94 against a specificity of 0.76, to discriminate DS-AD and participants without cognitive decline according to ROC analysis. The convergent validity against the CAMDEX-DS interview score was good (r = 0.74), and split-half reliability (r = 0.96), internal consistency (Cronbach's α r = 0.96), test-retest reliability (r = 0.88) (n = 25) and interrater reliability (r = 0.81) (n = 31) were excellent. CONCLUSIONS: The DSQIID-G showed excellent psychometric properties, including concurrent and internal validity and reliability. The cut-off value for screening was lower than in the original English validation study. For a screening instrument like DSQIID-G, a lower cut-off is preferable to increase case detection.
RESUMO
BACKGROUND: Although people with Down's syndrome (DS) are at a high risk of developing an Alzheimer type dementia (AD) due to a triplication of the amyloid precursor gene, there are practically no internationally available test procedures to detect cognitive deficits in this at risk population in the German language. OBJECTIVE: The aim was to provide a German translation and intercultural adaptation of the Cambridge examination for mental disorders of older people with Down's syndrome and others with intellectual disabilities (CAMDEX-DS), which is available in English and Spanish. This instrument for diagnostics and monitoring consists of a psychological test examination (CAMCOG-DS) and a caregiver interview. METHODS: The translation and adaptation of the CAMDEX-DS were achieved through a multistep translation process, whereby two independent forward and back translations were provided by professional translators and a consensus version was finalized and tested. The final version of the caregiver interview was applied to 11 subjects and the CAMCOG-DS was conducted with 28 patients. RESULTS: The German version of the CAMDEX-DS proved to be easily administered. The CAMCOG-DS could be fully administered to 21 out of 28 patients (75%). The CAMCOG-DS values were much lower for older patients aged ≥45 years than for younger patients (46/109 vs. 73.5/109; pâ¯= 0.033). DISCUSSION: The German version of the CAMDEX-DS provides an internationally recognized tool for the diagnostics and monitoring of cognitive decline in Down's syndrome. Furthermore, the German version can standardize medical care of these patients. In particular it provides a means of participation in international research trials for this at risk population.