Date Published: January 02, 2019
Author(s): Jessica Budgett, Anna Brown, Stephanie Daley, Thomas E. Page, Sube Banerjee, Gill Livingston, Andrew Sommerlad.
The psychometric properties of the social functioning in dementia scale over different dementia severities are unknown.
We interviewed 299 family carers of people with mild, moderate, or severe dementia from two UK research sites; examined acceptability (completion rates); conducted exploratory factor analysis; and tested each factor’s internal consistency and construct validity.
Of 299, 285 (95.3%) carers completed questionnaires. Factor analysis indicated three distinct factors with acceptable internal consistency: spending time with other people, correlating with overall social function (r = 0.56, P < .001) and activities of daily living (r = −0.48, P < .001); communicating with other people correlating with activities of daily living (r = −0.66, P < .001); and sensitivity to other people correlating with quality of life (r = 0.35, P < .001) and inversely with neuropsychiatric symptoms (r = −0.45, P < .001). The three factors' correlations with other domains were similar across all dementia severities. The social functioning in dementia scale carer version measures three social functioning domains and has satisfactory psychometric properties in all severities of dementia.
Decline in social functioning, defined as “how individuals associate and interact, both in society at large and their own personal environment” , accompanying cognitive deterioration is part of the diagnostic criteria for dementia . Such changes can occur in the early stages of a number of conditions causing dementia, including Alzheimer’s disease  and frontotemporal dementia . Putative mechanisms include disruption to the amygdala and frontal cortex network  or deficits in emotion recognition  or theory of mind . Changes in social function, such as reduced engagement in close relationships or lack of interest in previously valued hobbies, are distressing to people with dementia ,  and can be upsetting and stressful for family carers  especially when the person with dementia lacks awareness of these changes . However, social change is not routinely asked about or reported as a symptom in clinical settings .
This cross-sectional study of family carers of people with dementia was nested in the CDEMQOL study (Alzheimer’s Society project grant: 234 AS-PG-14-017), and the South Central–Hampshire A Research Ethics Committee gave ethical approval (15/SC/0605).
We recruited 300 study participants; one carer withdrew before completing SF-DEM, so we included data from 299 carers. Table 1 summarizes the demographic and clinical characteristics of participants and their relatives with dementia. The mean age of family carers was 63 years (standard deviation [SD] 14), and three-quarters were female. The mean age of people with dementia was 81 years (SD 8), and 60% were female. Nearly half the participants were daughters or sons of the person with dementia, and most of the others were spouses or long-term partners of the person with dementia. Alzheimer’s disease was the commonest dementia subtype, and there was a range of dementia severity; over two-thirds had mild or moderate dementia.Table 1Clinical and demographic characteristics of participantsCharacteristicCarers (n = 299)People with dementia (n = 299)Mean (SD), rangeAge (years)63 (14), 21-9081 (8), 55-98n (%)Sex Female218 (73)179 (60)Ethnicity White British253 (84.6)241 (80.6) White – Other26 (8.7)38 (12.7) Black and minority ethnic19 (6.7)20 (6.6)Marital status Married/cohabiting238 (79.6)164 (55.2) Widowed5 (1.7)108 (36.4) Single36 (12)4 (1.3) Divorced/separated20 (6.7)21 (7.1)Level of education No qualification23 (7.7)77 (26.6) School (O levels/A levels)79 (26.5)91 (31.5) Degree/postgraduate145 (48.7)75 (25.9) Other30 (12.8)46 (15.9)Living situation of carer Resident carer150 (50.2) Nonresident carer148 (49.5)Living situation of PWD Lives alone53 (17.7) Lives with others248 (82.3)Carer relationship to PWD Spouse/long-term partner128 (42.8) Son/daughter148 (49.5) Other13 (7.7)Employment status Paid employment109 (36.5) Unemployed/retired/full-time carer190 (63.5)Dementia subtype Alzheimer’s disease159 (53) Vascular36 (12) Other79 (263) Not known25 (8.3)Mean B-ADL score (SD)27.85 (16.32)Mean NPI score (SD)24.12 (20.01)Mean DEMQOL-proxy score (SD)94.55 (14.29)CDR, very mild, n (%)31 (10.4)CDR, mild, n (%)108 (36.1)CDR, moderate, n (%)99 (33.1)CDR, severe, n (%)61 (20.4)Abbreviations: SF-DEM, Social Functioning in Dementia scale; SD, standard deviation; PWD, person with dementia; B-ADL, Bristol Activities of Daily Living Scale; NPI, Neuropsychiatric Inventory; DEMQOL, Dementia Quality of Life scale; CDR, Clinical Dementia Rating scale score.
We report results from this large multicenter study testing the psychometric properties of the carer-rated SF-DEM. These data suggest that the scale is an acceptable, reliable, and valid tool for measuring the social functioning of a person with dementia of any severity. Our EFA indicates that SF-DEM measures three distinct factors related to social functioning: spending time with other people, communicating with other people, and sensitivity to other people and that the corresponding sum scores had acceptable internal consistency as estimated by coefficient α. We found, as expected, that spending time with other people and communicating with other people decline with dementia progression, but this was not the case for sensitivity to other people, which varied little at differing dementia severities, possibly suggesting that this factor reflects premorbid personality .