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Functional abilities and cognitive decline in adult and aging intellectual disabilities. Psychometric validation of an Italian version of the A lzheimer's F unctional A ssessment T ool ( AFAST ): analysis of its clinical significance with linear statistics and artificial neural networks
Author(s) -
De Vreese L. P.,
Gomiero T.,
Uberti M.,
De Bastiani E.,
Weger E.,
Mantesso U.,
Marangoni A.
Publication year - 2015
Publication title -
journal of intellectual disability research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.941
H-Index - 104
eISSN - 1365-2788
pISSN - 0964-2633
DOI - 10.1111/jir.12113
Subject(s) - psychology , dementia , discriminant validity , intellectual disability , activities of daily living , gerontology , raw score , cognition , internal consistency , psychometrics , developmental psychology , clinical psychology , statistics , psychiatry , medicine , raw data , mathematics , disease , pathology
Abstract Purpose (a) A psychometric validation of an Italian version of the A lzheimer's F unctional A ssessment T ool scale ( AFAST‐I ), designed for informant‐based assessment of the degree of impairment and of assistance required in seven basic daily activities in adult/elderly people with intellectual disabilities ( ID ) and (suspected) dementia; (b) a pilot analysis of its clinical significance with traditional statistical procedures and with an artificial neural network. Methods AFAST‐I was administered to the professional caregivers of 61 adults/seniors with ID with a mean age (± SD ) of 53.4 (± 7.7) years (36% with D own syndrome). Internal consistency ( C ronbach's α coefficient), inter/intra‐rater reliabilities (intra‐class coefficients, ICC ) and concurrent, convergent and discriminant validity ( P earson's r coefficients) were computed. Clinical significance was probed by analysing the relationships among AFAST‐I scores and the S um of C ognitive S cores ( SCS ) and the S um of S ocial S cores ( SOS ) of the D ementia Q uestionnaire for P ersons with I ntellectual D isabilities ( DMR ‐I) after standardisation of their raw scores in equivalent scores ( ES ). An adaptive artificial system ( A uto C ontractive M aps, AutoCM ) was applied to all the variables recorded in the study sample, aimed at uncovering which variable occupies a central position and supports the entire network made up of the remaining variables interconnected among themselves with different weights. Results AFAST‐I shows a high level of internal homogeneity with a C ronbach's α coefficient of 0.92. Inter‐rater and intra‐rater reliabilities were also excellent with ICC correlations of 0.96 and 0.93, respectively. The results of the analyses of the different AFAST‐I validities all go in the expected direction: concurrent validity ( r = −0.87 with ADL ); convergent validity ( r = 0.63 with SCS ; r = 0.61 with SOS ); discriminant validity ( r = 0.21 with the frequency of occurrence of dementia‐related B ehavioral E xcesses of the A ssessment for A dults with D evelopmental D isabilities, AADS‐I ). In our sample age and gender do not correlate with the scale and comparing the distribution of the AFAST‐I and DMR ‐ SCS and DMR ‐ SOS expressed as ES , it appears that memory disorders and temporal and spatial disorientation ( SCS ) precede the loss of functional abilities, whereas changes in social behaviour ( SOS ) are less specific in detecting cognitive deterioration sufficient to provoke functional disability and vice versa. The results of AutoCM analysis reveal that the hub (core) of the entire network is represented by the functional domain ‘personal/oral hygiene’ in the entire study sample and ‘use of toilet’ in a subgroup of subjects who obtained an ES equal to 0 at DMR ‐ SCS . Conclusions These results confirm the reliability and validity of AFAST‐I and emphasise the complexity of the relationship among functional status, cognitive functioning and behaviour also in adults/seniors with ID .