1. Introduction
Motoric cognitive risk syndrome (MCR) is defined as a condition profile that combines a reduced walking speed and subjective memory complaints (SMC). It is a known indicator of an elevated risk of incident dementia [
1,
2]. A number of meta-analyses and longitudinal studies have demonstrated a correlation between MCR and the incidence of dementia [
3,
4,
5]. Prior research has demonstrated that MCR is linked to diminished cerebral volume [
6,
7,
8] and pathological alterations in the vasculature of cerebral white matter [
9]. Additionally, it is associated with lacunar lesions and frontal lobe dysfunction, encompassing the premotor and prefrontal cortices [
3,
10]. Recently, it has been reported that MCR reflects various other risks besides dementia. For example, MCR has been shown to reflect the risk of falls, disability, and death. Furthermore, these trends have been observed to manifest similarly across racial groups [
11,
12].
The prevalence of MCR is subject to variation according to the findings of previous studies. Recent meta-analyses report a prevalence of MCR of 10.0% (95 CI: 8.0–12.0%) worldwide [
13] and 6.4% [
14] and 11.1% [
15] in Japan. In Japan, MCR has also been reported to be associated with diabetes, depressive symptoms, falls and disability [
14,
16]. However, there is a paucity of studies examining the association between MCR and key indicators that are crucial for older people to maintain their independence living in the community.
In recent years, there have been reports indicating that social participation plays a significant role in maintaining the health and well-being of older individuals [
17]. A state of social frailty has been identified as a risk factor for physical and cognitive decline, as well as an increased likelihood of developing disabilities [
18,
19]. Indeed, social frailty has been linked to an elevated risk of incident MCR [
20]. It can be reasonably inferred that there may be a correlation between MCR and social participation. Therefore, there may be a link between MCR and social participation. However, the extent to which MCR affects older people’s higher levels of functional living capacity, including aspects of social participation, has yet to be elucidated. It is also known that cognitive and gait functions, which are components of MCR, are closely related to each other [
21], and a decline in one function will cause the other to follow suit. This suggests that MCRs may reflect earlier signs that an elderly person’s health is beginning to decline.
In Japan, for example, a questionnaire survey called the Kihon checklist has been used to identify older people who are likely to require long-term care and to implement care prevention programs. However, the government’s estimate that about 5% of the elderly who are not certified as requiring long-term care should be eligible for long-term care prevention projects has not been reached, and the actual figure is less than 1% [
22]. Alternatively, the Community Rehabilitation Activity Support Program, which promotes the involvement of rehabilitation professionals to strengthen care prevention efforts in the community, was launched in 2012. However, 65.2% of all municipalities in Japan have dispatched physiotherapists and 46.8% of occupational therapists, leaving a shortage of professionals who can contribute to care prevention in the community [
23]. In addition, the Questionnaire for Medical Checkup of the Old-Old (QMCOO) has been adopted from 2020 [
24], but its ability to predict incident disability among the elderly has yet to be verified [
25]. Therefore, in Japan, a super-aged society, there is a need for a simple disability prediction tool to complement the Kihon checklist and the QMCOO.
The present study was designed to test the hypothesis that MCR is an indicator that reflects independent living indicators such as social participation and the health status of the elderly. To test this hypothesis, an MCR assessment was conducted on community-dwelling older adults as well as a comprehensive evaluation of health status and social participation, and the association between these factors and MCR was examined. Furthermore, the extent to which MCR explains the health status and social participation of the elderly, independently of the conventionally used measures of physical frailty and sarcopenia, was examined.
4. Discussion
This study aimed to test the hypothesis that MCR is associated with various health indicators in community-dwelling older adults. Furthermore, the extent to which MCR was associated with the health indicators utilized in this study was examined in comparison to the established risk indicators of physical frailty and sarcopenia. The main findings indicate that MCR is associated with the health status (QMCOO) and higher life functioning (JST-IC) of community-dwelling older adults. Moreover, MCR was identified as a reflective indicator of the health status and higher life functioning of older individuals, exhibiting similarities to physical frailty.
The prevalence of MCR in the participants of this study was 12.1%, which is generally comparable to the MCR prevalence in previous studies [
13] (range 4.22–14.74). The cut-off value of gait speed for determining MCR in this study was 0.85 m/s, which is the mean −1 SD value of the participants. The mean gait speed of the MCR participants was 0.75 ± 0.09 m/s. This cut-off value for gait speed is comparable to those used in other studies on Japanese subjects [
14,
15,
16], and the results of the present MCR determination appear to be generally valid.
One of the findings of the present study was the discovery of an association between QMCOO and MCR. The QMCOO is designed to encompass a comprehensive range of frailty conditions, many of which may be associated with physical frailty. Indeed, the possibility of physical frailty determination has been investigated by QMCOO and it has been reported that frailty determination is possible [
29,
40]. The QMCOO questions include ‘7: Do you think you walk slower than before?’, which asks about subjective gait speed reduction. In addition, there are questions such as ‘10: Do your family or your friends point out your memory loss? For example, you ask the same question over and over again’ or ‘11: Do you find yourself not knowing today’s date?’, which are questions about cognitive decline, similar to the MCR judgement. This feature of the QMCOO structure is the reason why it was found to be associated with MCR. A recent study reported that subjective MCRs reflect the original MCR [
41], which also supports the interpretation of the present findings.
On the other hand, the association between JST-IC and MCR is another interesting finding of this investigation. The JST-IC encompasses a range of higher levels of functional living capacity that are essential for older adults to maintain an independent lifestyle. The JST-IC questionnaire encompasses competencies that necessitate advanced cognitive functioning, including information literacy and the utilization of novel equipment. With regard to cognitive functioning, there have been reports indicating that SMC is associated with health literacy [
42] and that the capacity to utilize everyday technology begins to decline at the SMC stage [
43,
44]. In this context, it is noteworthy that higher levels of functional living capacity in older individuals necessitate the maintenance of a high level of cognitive function and that MCR was associated with indicators of older individuals’ ability to live independently.
The final indicator, social frailty, showed no correlation with MCR. However, a longitudinal study examining the association between social frailty and the incidence of MCR [
20] has shown that individuals with social frailty are at an elevated risk of developing MCR compared to those without social frailty. The fact that this study used a cross-sectional design and the restriction of the participants to a single city may have contributed to the absence of an association between MCR and social frailty. It should be noted that the QMCOO and JST-IC include questions pertaining to social participation. In the QMCOO, three of the total fifteen questions are related to social participation and social support, whereas in the JST-IC, four of the total sixteen questions are concerned with social participation. It has been reported that social participation can reduce the risk of physical functional decline [
17,
45] and reduce the risk of developing a need for long-term care [
17] in community-dwelling older adults. The findings of the present study indicate that MCRs do not fully account for social participation status. Therefore, a separate assessment of the social participation of community-dwelling older adults needs to be carried out.
Our findings suggest that MCRs may enable community-dwelling older adults to assess their higher levels of functional living capacity and health status, which are important factors in independent living, through a simple and easy-to-assess MCR. Furthermore, SMC and SG, which are components of the MCR, have been demonstrated to reflect a range of adverse events when assessed individually [
46,
47,
48]. Therefore, the MCR should be used for screening community-dwelling older adults because, in addition to being a simple assessment, it reflects the comprehensive health status and higher life functions of older people. However, there are challenges in using the MCR as a replacement for conventional assessment tools such as frailty and sarcopenia. More careful assessment is needed to identify in detail the problems of older people with varying degrees of frailty. In such cases, surveys and medical examinations using QMCOO and the Kihon checklist [
49] are considered necessary. However, as the MCR assessment does not require any special expertise, it can be used to help community-based long-term care prevention projects to identify the target population. Alternatively, it could be used to improve health awareness by having residents conduct MCR assessments among themselves.
The limitations of this study should be noted. First, the study is a cross-sectional study and cannot explain the causal relationship between MCR and community-dwelling older adults’ health status (QMCOO) and higher life functioning (JST-IC). Secondly, the study’s participants were older people living in a particular area, so the results may reflect effects specific to the area of interest. Third, the participants in this study participated in a self-management exercise group, and the influence of this activity may be reflected in the results. Fourth, there are many other factors that can influence health status and higher life functions than those addressed here, which have not been taken into account (e.g., built environment, objective medical information, etc.). In addition, global cognitive function tests such as the MMSE were not available for the subjects in this study. In recent years, it has become known that the presence of negative affect as well as depressive symptoms in older people can have a negative impact on independent living and daily functioning [
50,
51]. It is also known worldwide that the prevalence of frailty is higher in women. There are interesting findings that the higher prevalence of frailty in women is related to financial exploitation [
52], and we believe that it is important to discuss this issue in the future, taking into account different cultural backgrounds and gender and their impact on independent living among the elderly.
Future research should follow participants longitudinally, complementing factors affecting health status and higher life functioning, to demonstrate the effectiveness of conducting MCR determinations for community-dwelling older adults.