Background
During the second half of the last century, there was a vast increase in the number of people aged 60 and above, from 205 million people worldwide in 1950 to 606 million people in 2000 [
1]. This number is expected to increase to almost two billion in 2050. Within this group of older adults, the group of people aged 80 and above is increasing the fastest [
2]. As age is an important risk factor for dementia [
3], an increase is also expected in the number of people with dementia, from about 35.6 million people in 2010, to 115.4 million in 2050 [
4]. One of the main characteristics of dementia is a progressive cognitive decline [
5]. In the most prevalent subtypes of dementia, Alzheimer’s disease and vascular dementia [
6], cognitive functions such as memory and executive functions (EF) already decline in an early stage of the disease, although in a different degree for both subtypes [
7].
With the decline in cognitive functions, the dependency of people with dementia increases [
5]. Indeed, for many subtypes of dementia, a decline in cognitive functions is associated with increasing limitations in activities of daily living (ADL) [
8]. Other aspects of daily life functioning, such as physical functioning, are also altered in dementia. Functional mobility and muscle strength already decline over the adult lifespan [
9], and physical functions such as mobility and lower extremity strength decline even more in people with dementia [
10]. In both older adults and people with dementia also several gait disturbances are present [
11]. Depending on the presence and subtype of dementia, these gait disturbances are, for example, wide base, decreased velocity, and decreased step length. Additionally, the rest-activity rhythm becomes weaker and more fragmented over the adult lifespan [
12]. In people with dementia, many sleep disturbances such as a disrupted sleep-wake rhythm are present [
13].
Because of the negative influences of dementia on multiple aspects of daily life, and no cure for dementia is available yet [
14], it is of clinical relevance to find a way to decrease the decline in these functions or even improve them. This could be achieved by an increase in physical activity. Physical activity has been shown to have multiple beneficial effects for older adults in general. Not only is physical activity an important factor in maintaining health [
15], it has also been found to be beneficial for mobility/physical functioning [
16], to lower the risk of (progression of) ADL disability [
17], to reduce depressive symptoms in older adults with depression [
18,
19], and, although based on only one study of 10 male participants, to influence the rest-activity rhythm by reducing its fragmentation [
20]. Exercise may also have beneficial effects on several aspects of cognition, but the findings for this outcome measure are more equivocal [
21,
22]. The same holds for quality of life (QoL), on which beneficial effects have also been found in some but not all studies [
23].
Despite the numerous beneficial effects of physical activity, many older adults are insufficiently active. Even though the percentage of older adults that meets the recommended physical activity level varies widely across studies, most of the reported percentages do not exceed 50% [
24]. The level of inactivity is higher in older adults than in younger age groups [
25], and people living in nursing homes or other residential care facilities seem to have even higher levels of inactivity than their community-dwelling counterparts [
26-
28]. Many people with dementia relocate to a nursing home, which implies they are at a higher risk of becoming sedentary. Being physically active is however not only found to be effective for older adults in general, also older adults with cognitive decline or dementia may experience beneficial effects from physical exercise. Beneficial effects have been reported on for example, mobility/physical functioning [
29], ADL [
10] and cognitive function [
22]. However, for cognitive function findings were more equivocal [
22].
Because of the beneficial effects of physical activity, it is important to motivate older people with dementia to become more physically active. Of all physical activities, walking is among the easiest to perform in daily life [
30]. Many people are able to perform this activity, which makes walking a suitable activity to encourage older adults to do. However, it is time-consuming for caregivers to go for a walk with residents on a regular basis. Moreover, considering the expected increase in the number of older adults [
1], as well as in the ratio of older adults to the working-age population [
31], it will most likely become harder for caregivers to find time to motivate older people for and supervise them in the participation in a walking activity. A more feasible and less demanding way to increase walking and obtain its beneficial effects in older adults with dementia may be activation of the mirror neuron system (MNS) through action observation.
Mirror neurons become activated both when people perform an action themselves, and when they see someone else perform the same action [
32]. The MNS seems to become activated only if an observed action exists in one’s own motor repertoire [
33], and it becomes activated more if the specific motor skill observed is acquired better, that is, expertized [
34]. Clearly, for ambulatory people, walking is an action that meets both these ‘requirements’. Walking can be considered a voluntary movement, as opposed to an affective movement. The MNS that is activated in the recognition of voluntary movements, the parietofrontal MNS, consists of the parietal lobe, the premotor cortex (PMC), and the posterior inferior frontal gyrus [
33]. Both the PMC and the parietal lobe are activated in a somatotopic way [
35]. Areas that are activated during observation of foot movements related to an object (e.g., ball kicking), are the dorsal sector of Brodmann’s area 6, and posterior parts of the parietal lobe (Brodmann’s areas 7 and 39). In addition, during observation of a person walking corticospinal excitability has been found to increase [
36].
Observation of an action seems to have a facilitative effect on the execution of the observed action, as has been found for the movement onset of finger movements [
37]. Furthermore, activation of the MNS through action observation has been shown beneficial, for example, for the rehabilitation of motor functions after stroke [
38]. In the described studies, participants that both observed and executed a specific action (i.e., action observation therapy), showed a larger improvement in the function concerned than participants who performed the action without observing it. Action observation therapy has also been shown to decrease the number of freezing of gait episodes in patients with Parkinson’s disease for a longer period of time than practicing the action and watching images of landscapes [
39]. Another pilot study showed a greater improvement in daily actions in patients with Parkinson’s disease who received action observation therapy, than in patients who performed the actions and watched videos in which no physical movements were shown [
40].
Based on among others the activation of the PMC and the corticospinal excitability induced by observing an action, observing a certain movement (e.g., walking) may facilitate people to initiate the execution of that movement. This may increase their amount of physical activity. Furthermore, based on the effects of action observation therapy on the execution of the observed action, and the beneficial effect of physical activity on physical functioning and ADL, these physical performance measures may also improve. This would imply that also the quality of movements may improve as a result of action observation. Thus, the primary hypothesis in this study is that the observation of videos of walking people will have a beneficial effect on the amount of physical activity (walking) as well as on physical performance (the ‘quality’ of movements, e.g., physical functioning and ADL) in older adults with dementia. In addition, secondary effects may follow directly from action observation and/or indirectly through an increase in physical activity. The secondary hypothesis, therefore, is that the observation of videos of walking people has beneficial effects on cognition and QoL related outcomes (i.e., the rest-activity rhythm, QoL and depression). In sum, this study aims to examine the effects of observation of walking on physical, cognitive, and QoL related outcome measures in older adults with dementia.
Discussion
The aim of this study is to examine the effect of observing videos of walking people on physical activity, physical functioning, and ADL, as well as on cognitive functioning, the rest-activity rhythm, QoL and depression, in older adults with dementia. This is examined using an RCT design, in which videos are shown in shared living rooms of residential care facilities. Since it is not possible to have participants of both conditions in the same living room (this would require videos of both conditions being shown in one living room, causing participants of each group to see videos of both conditions), living rooms instead of individual participants are randomly assigned to the experimental or control condition.
This study has several strengths. First, the study is highly feasible. For the intervention days, the only actions that are asked of caregivers are turning the televisions on and off, and writing down a minimum amount of information. This also implicates that if this intervention has beneficial effects on one or more of the outcome measures, the intervention is easily applicable in daily life in residential care facilities, and possibly also in home care settings. The applicability is due to the little amount of time needed, that is, only for turning on and off the televisions, and also to the limited associated costs. Another strength of this study is that it gives an extensive insight in the effects of the intervention on (the quality of) daily life functions, such as physical functioning, as well as on QoL itself. Additionally, some outcome measures are measured objectively, through the use of actometers or sensors.
There are also challenges in this study. Actually, one of the advantages of the study is a challenge at the same time. Since the intervention does not require much time and attention from caregivers or researchers, they are not necessarily present in the living room all the time. It is therefore difficult to get a good idea of whether and how long residents are present in the room, and how long they watch the videos. This is overcome as good as possible, without the need for much additional time and effort, by asking caregivers to write down whether participants were present/absent in the living room during an intervention day. In addition, to know whether participants watch the videos being shown, additional observations are made by the researchers by means of behavioral and focal sampling techniques.
Another aspect to take into consideration is the large number of tests that is administrated. Especially the duration of the complete neuropsychological test battery containing the DQoL may be demanding for the participants. Therefore, test administrators are instructed to pay attention to among others fatigue of participants, and, if necessary, look for a good moment for a short break, or even postpone a part of the test administration.
Beneficial effects may obviously manifest themselves through improvements in the outcome measures. However, as partly reasoned elsewhere [
52], since many of the measured functions typically decline with age and/or dementia, stabilization or a decreased decline in these functions would also be an important beneficial effect of the intervention. Indifferently how the beneficial effects will manifest themselves, this intervention is expected to be a feasible means for these beneficial effects to occur. In sum, observing videos of walking people is expected to give rise to beneficial effects on physical activity, physical performance, cognition, and QoL related outcome measures, in older adults with dementia.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
JGD designed the study together with EJAS and KMV. JGD wrote the manuscript, receiving critical feedback from EJAS, KMV, PJV, MHS, and RHMG. PJV and JGD wrote the statistical sections of this manuscript together. All authors read and approved the final manuscript.