We aimed to psychometrically evaluate and validate a Japanese version of the Social Functioning in Dementia scale (SF-DEM-J) and investigate changes in social function in people with dementia during the coronavirus disease-19 (COVID-19) pandemic.

We interviewed people with mild cognitive impairment (MCI) and mild dementia and their caregivers during June 2020–March 2021 to validate patient- and caregiver-rated SF-DEM-J and compared their scores at baseline (April 2020 to May 2020) and at 6–8 months (January 2021 to March 2021) during a time of tighter COVID-19 restrictions.

The neuropsychology clinic in the Department of Psychiatry at Osaka University Hospital and outpatient clinic in the Department of Psychiatry and Neurology at Daini Osaka Police Hospital, Japan.

103 dyads of patients and caregivers.

SF-DEM-J, Mini-Mental State Examination, Neuropsychiatric Inventory, UCLA Loneliness Scale, and Apathy Evaluation Scale.

The scale’s interrater reliability was excellent and test–retest reliability was substantial. Content validity was confirmed for the caregiver-rated SF-DEM-J, and convergent validity was moderate. Caregiver-rated SF-DEM-J was associated with apathy, irritability, loneliness, and cognitive impairment. The total score of caregiver-rated SF-DEM-J and the score of Section 2, “communication with others,” significantly improved at 6–8 months of follow-up.

The SF-DEM-J is acceptable as a measure of social function in MCI and mild dementia. Our results show that the social functioning of people with dementia, especially communicating with others, improved during the COVID-19 pandemic, probably as a result of adaptation to the restrictive life.

Diabetes mellitus (DM) is known to be one of the risk factors for cognitive decline and dementia. Neuropsychiatric symptom (NPS) is present not only in dementia, but also mild cognitive impairment (MCI). In this study, we examined NPS of MCI with DM and compared MCI with DM and our MCI database to investigate the characteristics of MCI with DM.

The participants were subjects who were diagnosed as MCI from type 2 DM participants enrolled in Osaka University Hospital. To estimate NPS, we used Neuropsychiatric Inventory (NPI) score.

The number of MCI subjects with DM who were estimated NPS was 19. According to the NPI score, apathy is the most severe symptom in MCI (average score = 2.5±3.3). This result was the same as the score of our database. In the frequency of NPS, there was no difference between the results in NPI of MCI with DM and MCI of our data (n = 225) except for sleep disturbance and appetite/eating disturbance (chi-squared test, P < 0.05). The sleep disturbance was more frequent in MCI with DM than in MCI of our database. On the other hand, the appetite/eating disturbance was less frequent in in MCI with DM than in MCI of our database. Moreover, the appetite/eating disturbance was not observed in MCI with DM.

NPS of MCI with DM is almost the same as MCI of our database except for sleep disturbance and appetite/eating disturbance. This result might be influenced by the disorder of lifestyle habits that is often observed in patients with DM or cognitive impairment of DM.

The limitation of our study is the small number of cases, further investigation is needed.

The present study aimed to compare the social function between mild cognitive impairment (MCI), mild Alzheimer’s disease (AD) dementia, and mild dementia with Lewy bodies (DLB) using the Japanese version of Social Functioning in Dementia scale (SF-DEM-J).

We interviewed 103 patients and family caregivers from June 2020 to March 2021: 54 patients with MCI, 34 with mild AD dementia, and 15 with mild DLB. We compared the caregiver-rated SF-DEM-J, Clinical Dementia Rating (CDR), MMSE, age, length of education, Geriatric Depression Scale (GDS), the University of California, Los Angeles Loneliness Scale (UCLA-LS), Neuropsychiatric Inventory (NPI), and informant version of the Apathy Evaluation Scale (AES) between MCI, mild AD dementia, and mild DLB groups using Kruskal-Wallis test with Dunn-Bonferroni correction for post-hoc analyses. We compared sex, living situation, and caregiver demographics between three groups using chi-square test. We performed correlation analysis between the score of each psychological test and the scores of SF-DEM-J within group using Spearman’s rank correlation coefficient.

For SF-DEM-J, the score of section 2 (communicating with others) was significantly worse in mild AD dementia than in mild DLB. The scores of section 1 (spending with others) and section 3 (sensitivity to others) and the total score did not significantly differ between three groups. The score of section 1 was significantly associated with MMSE in MCI, with anxiety and disinhibition of NPI, and AES in mild AD dementia, and with GDS in mild DLB. The score of section 2 was significantly associated with AES in MCI and mild AD dementia, with UCLA-LS in MCI, and with the length of education in mild DLB. The score of section 3 was significantly associated with agitation and irritability of NPI in MCI and mild AD dementia. The total score was associated with UCLA-LS and AES in MCI, and with AES in mild AD dementia.

Factors affecting social functioning differed between MCI, mild AD dementia, and mild DLB. Apathy, agitation and irritability affected social functioning in MCI and mild AD dementia while depressive mood affected social functioning in mild DLB.