Search results

The database search yielded 2356 publications and a further 40 were included from reference harvesting and the free search. Duplicate publications were removed (n=173), and following three screening phases, 61 publications were eligible and included in the review. Once duplicate reports were collated, a total of 33 original studies were identified and subject to detailed review. Descriptions of these studies can be found in table 1.

The inter-rater agreement between the reviewers were calculated to be 0.91 for the title screen, 0.64 for the abstract screen and 0.89 the final report, demonstrating very good, good and very good correlation between the reviewers, respectively, according to Cohen’s Kappa coefficient.10

Figure 1 outlines a Preferred Reporting Items for Systematic Reviews and Meta-Analyses schematic flow diagram of the review process and reasons for exclusion.11

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Figure 1

Schematic flow diagram of the review process.

Participants and settings

Across the studies, 1574 participants were included. However, due to inconsistent reporting, overall age and gender information are not available. All participants were considered elderly, and among the studies that reported age information (n=28; 1411 participants), only one participant was under the age of 60 years. The number of participants included in any given study varied from 3 to 415 subjects. In the 24 studies that reported gender information (comprising 1264 participants), 71% of the participants were women. The majority of studies exclusively assessed participants with a dementia diagnosis (n=18; 1036 participants), while a further six studies (151 participants) included some patients with dementia. A large proportion of studies were conducted in Japan (n=10; 178 participants), the USA (n=8; 182 participants) and Australia (n=4; 577 participants). The most common setting was the nursing home (n=17; 621 participants). In total, 11 robot systems were used across the studies. Assessed in 22 of the 31 studies, Paro was the most popular choice of SAR intervention. Robots are divided into those capable of learning responses, such as NAO using closed-loop architecture, and those which cannot, such as Paro, using open-loop architecture. In total, only two closed-loop robots were used (NAO and AIBO) in a total of six studies. Descriptions of individual robot systems reviewed can be found in table 2.

Identified roles of SARs

Eligible studies were organised into sets by the role assumed by SAR. Five roles were identified: affective therapy, cognitive training, social facilitator, companionship and physiological therapy. Specific details of the studies below, such as assessment tools or subject demography, are described in table 1.

Affective therapy

Fifteen studies (889 participants) evaluated the effect SAR can have in improving the general mood and well-being of elderly participants, or its ability to overcome episodes of mood disturbance. In this review, this role is collectively termed affective therapy. Nine of these studies (650 participants) were conducted on participants diagnosed with dementia. In total, 11 reported positive findings including reductions in depression scores, agitation scores and increases in quality of life scores. While these studies were evaluating similar effects of SAR, their intervention design can broadly be divided into two types: one-on-one interactions with SAR or group interactions with SAR.

Eight studies (657 participants) assessed SAR in one-on-one settings, whereas the remaining seven studies (232 participants) had group settings. All of the group setting studies reported positive findings, including reduced agitation and depression levels and higher expression of positive emotions. Of the eight one-on-one interaction studies, only five report positive findings. Indeed, two of these studies12 13 report negative findings with increased agitation and worsening dementia, respectively.

These contrasting set of results could indicate a mechanism of how elderly users gain emotional benefit from SAR. A Japanese pilot study14 assessed group interactions of 26 subjects with Paro and found significant improvements in mood scores during the intervention period. Of note, the authors commented on improved sociability between subjects. As discussed later, several studies15–19 demonstrate that SAR can increase the sociability of subjects within groups, which may play a direct role in the mood changes seen here.

Notwithstanding this, however, a Dutch crossover study20 compared two types of one-on-one intervention: therapeutic interventions (Paro introduced at times when subject was distressed) and care support interventions (Paro introduced to facilitate activities of daily living). Only the therapeutic intervention showed a significant improvement in the mood score (P<0.01). This suggests that perhaps while group interventions may be better at generating positive emotions, one-on-one interventions may be appropriate to remedy negative emotions.

Some studies in this set also investigated how SAR compared with soft toys in improving general mood and well-being of participants. A large Australian randomised controlled trial (RCT)21 of 415 participants with dementia compared one-on-one interventions with Paro switched ‘on’ and Paro switched ‘off’ (placebo Paro) to identify if Paro’s additional social capabilities translated into any positive outcomes. The study found Paro was more effective than usual care in improving pleasure and agitation but was no different to placebo Paro. Similarly, a Japanese study8 compared the effect of group interactions with Paro and placebo Paro and again did not demonstrate any differences between the groups.

These results are mimicked by a Danish RCT13 of 100 subjects, which compared interactions with Paro, a living dog or soft toy cat. The study found intervention type did not affect cognitive state, independence or depression scores and did not affect sleep quality. However, depressive scores improved compared with baseline scores in all groups (P<0.05).

Indeed, only two small pilot studies found differences between SAR and soft toys. The first22 showed subjects engaged more with Paro (P<0.05) and showed more positive emotional expressions with Paro (P<0.01) when compared with a stuffed lion. The second23 was a study on participants with dementia; it showed that agitation scores were only significantly decreased in a toy cat (P<0.05), whereas NeCoRo (SAR—cat-like robot) only improved scores of pleasure and interest (P<0.01 and P<0.05, respectively).

Cognitive training

Six studies (344 participants) assessed whether SAR can improve aspects of cognition, such as working memory or executive function, and as such this review has termed this set cognitive training. This set included four studies (239 participants) that assessed elderly subjects with dementia, and two studies (105 participants) that assessed elderly subjects who were cognitively intact. Several robot types have been used in this set including two closed loop robots capable of learnt responses. This means that while broad conclusions surrounding the role of SAR in cognitive training can be made, the evidence for any individual robot system is limited. Five of the six studies (133 participants) concluded with positive findings, although there is a breadth of outcome measures used as surrogate markers for cognitive improvement.

Two studies used cognitive tests, such as Mini-Mental State Examination (MMSE) as the primary outcome measure to assess the impact of SAR interactions. The first was a RCT24 of 34 cognitively healthy subjects in Japan using the Nodding Kabochan as the SAR intervention. Subjects either received the fully functional Nodding Kabochan or a non-functional Nodding Kabochan (control) for 8 weeks. All interactions were one on one with the participant and the SAR in the participants’ home. Only subjects receiving the functional Nodding Kabochan demonstrated an improved cognitive function score (P<0.01) after the study period. This result contrasts with the conclusion of the previous set, affective therapy, where it was difficult to distinguish the positive effects between functional SAR and placebo toys. The distinction here may be that the Nodding Kabochan robot is a communication robot that can talk and sing with the user, a function that a placebo toy is incapable of. The communication itself may be key to this study’s findings.

The other study that used cognitive tests as an outcome measure for cognition was a two-phase block RCT.25 This Spanish study involved 101 and 110 subjects with dementia, in the respective phases, and assessed the cognitive effects of group interactions with SAR. In phase 1, the study compared open-loop system robot, Paro, with closed-loop robot, NAO, and a control group treatment as usual. Compared with control group, phase 1 showed a decrease in cognitive function scores in the NAO group only (P<0.05) at follow-up. Notably, there were no significant differences between NAO and Paro groups at follow-up. This set of results contrasts with the previous study conducted on cognitively healthy subjects in one-on-one settings. Given different robots systems have been used in the studies, it is difficult to establish which factor is responsible for differing results.

Two studies used neuroimaging modalities as outcome measures of interactions with SAR. The first was a South Korean study26 that used MRI in a RCT of 71 cognitively healthy subjects. The primary outcome measure was change in cortical thickness in brains of participants over the 12-week study period. Subjects were randomised into three arms: (1) robot-assisted group training using Silbot and Mero (SAR), (2) traditional intervention training, using computer software or (3) non-intervention arm - control. The study showed attenuation of cortical thinning on MRI in both intervention groups (P<0.05) and estimated it would take 15.3 months for intervention groups to reach the same level of cortical thinning as controls. This study also used neuropsychiatric tests as a secondary outcome measure. Both intervention groups showed greater improvement in the executive function scores than control group (P<0.001). However, in the general cognitive and visual memory tasks, the traditional intervention group had greater improvement than in the robot group. Indeed, the robot group did not outperform the traditional group on any neuropsychological tests. Both Silbot and Mero are communication robots, like the Nodding Kabochan, which may underpin the improvements in executive function. Nonetheless, the SAR arm did not prove to be any more effective than traditional computer software in either outcome measures for cognitive function.

The other study to use a neuroimaging modality was a Japanese pilot study27 of 14 subjects with dementia. This study investigated the neuropsychological influence of Paro within an interactive group setting by analysing the electroencephalogram (EEG) recordings. They found an increase in cortical neuronal activity in seven participants, particularly in participants who liked Paro. It is unclear what the clinical meaning of this finding is, and without a control group, one cannot distinguish the effect of SAR from any other stimulating activity on EEG.

The two final studies used game performance as a surrogate marker for cognitive function in participants with dementia. These were very small studies without control groups. The first28 included three subjects and found that verbal encouragement from SAR (Bandit) improved response time in a game quiz, while the second study, with 11 participants, concluded the participants’ performance in group ball games and individual card games improved following interactions with SAR (AIBO). Again, the clinical utility of this is unclear, and without objective outcome measures or control groups, there is little that can be learnt from these studies.

Social facilitator

Seven studies (230 participants) assessed the utility of SAR as facilitators for improved sociability between subjects or between subjects and other people. As such, this review has titled this role social facilitator. All of these studies concluded that the respective SAR intervention improved sociability of participants. Five of these studies (210 participants) were conducted with participants who had been diagnosed with dementia. Four of the studies used Paro as the SAR intervention, and two used AIBO, the robotic dog, which allowed for a greater degree of comparison between the studies. The final study used Sophie and Jack as the SAR intervention.

Most studies used observed behaviour changes on video recording or via a live assessor during the interaction period. One study16 used a validated communication scale to assess how group Paro interactions affected sociability. The study concluded that after the 4-week programme, a significant improvement in communication and interaction skills were exhibited by subjects (P<0.05) and an increase in activity participation (P<0.05).

Two studies compared SAR with comparative soft toys/animals. The first was a crossover study17 of 23 subjects in the USA. Subjects were grouped into sessions with Paro, placebo Paro or no object. The study concluded that the group with Paro engaged in more social interactions than the group with placebo Paro. This suggests that the sociability effects are associated with SAR itself. The authors note that the novelty around SAR may have contributed to the excitement manifested in increased social engagement. However, as this study was conducted over 4 months, any novelty effects would not likely have been sustained.

The other comparative study was another crossover study29 in the USA, which involved 18 female subjects with dementia. Subjects were divided into sessions with AIBO, a real dog or no object. The study concluded that although all visit types with AIBO, a dog or no object stimulated social interaction by the subject, there were no significant differences in the frequency of social behaviours exhibited by the subjects between visit types.

A similar US pilot study15 of seven subjects with dementia was instead conducted in a group setting. Subjects within a group were divided into primary users, those individuals who engaged with Paro at any one time, or non-primary users who were defined as everyone else in the group. The study showed an increase in social interaction over the 7-week period between primary and non-primary users towards each other and towards staff.

This study’s results are reflected in two larger, more recent studies that also investigate effects of group interactions with SAR on participants with dementia. The first is an Australian study18 of 139 participants conducted over 5 years with Sophie and Jack. The study reported that social engagement increased over the study period. The second was a Norwegian study19 with 23 participants that evaluated the effects of group interactions Paro on those with mild to moderate dementia compared with those with severe dementia. The study found that those with mild to moderate dementia paid more attention to Paro than those with severe dementia. The authors note that SAR interventions may need to be more tailored towards the degree of dementia severity. Another finding was that over the 12-week study period, there was a reported increase in interactions with other subjects and a decrease in interactions with Paro.

Companionship

Three studies (78 participants) assessed the utility of SAR in overcoming the feeling of loneliness and social isolation in the elderly. These studies are collected into a set this review has titled the companionship role. All three of the studies examining SAR in this role showed reductions in loneliness scores. None of these studies were conducted on patients with diagnosed dementia. Two studies used AIBO as the intervention, while the third used Paro.

Only one study assessed this in a one-on-one setting. This was a RCT30 of 38 subjects in the USA. Subjects were randomised to have weekly one-on-one sessions with a real dog, AIBO or no object (control). Subjects in the dog or AIBO group were significantly less lonely than those in the control group at week 7 (P<0.05, respectively). In both intervention groups, there was a higher attachment score compared with the control group. No significant differences were found between the dog and AIBO groups in the assessment of loneliness or attachment. This is an important finding that suggests an artificial animal (SAR) can be as effective a companion as a pet.

The other two studies were conducted in a group setting. The first study was a pilot study7 of 11 subjects in Japan using AIBO. Mean loneliness scores after the session were significantly lower than those before the session (P<0.05), although longer term benefits were not established. The second was a larger RCT31 of 34 subjects in New Zealand investigated the effects of Paro on loneliness. Subjects were randomised into a Paro group or a control group that attended normal activities. Subjects in the Paro group had a significantly greater decrease in loneliness score at the 12-week follow-up than the control group (P<0.05). This indicated that sustained effects can be achieved.

The last two studies do show promising results; however, in the context of the previous set of studies, the decreased sense of loneliness may result from increased sociability in the group setting. Sociability was not measured in either study and therefore may act as a confounder.

Physiological therapy

Two studies (33 participants) investigated the effects of SAR on physiological markers, and as such, this review titles this set physiological therapy. This clinical applicability of this set is less clear but does raise some questions that future studies may be able to answer. Both of these studies used Paro as the SAR intervention.

The first was a pilot study32 of 21 subjects in New Zealand and investigated the effect of Paro on blood pressure and heart rate. Subjects had a single 10 min session with Paro where they were free to interact with the robot. Blood pressure and heart rate was recorded before (T1), immediately after (T2) and 5 min after (T3) the 10 min interaction. Overall, no significant changes in blood pressure or heart rate were demonstrated; however, the study decided to exclude four residents who did not interact or touch the robot. Subsequently, significant decreases in systolic blood pressure (P<0.05) from T1 to T2 were shown, and such decreases were sustained at T3 measurement. Similarly, significant decreases in diastolic blood pressure (P<0.05) from T1 to T2 were shown; however, this decrease was not sustained at T3. Between T1 and T3, heart rate significantly decreased (P<0.05).

In the other study33 of 12 subjects in Japan, physiological effects of interacting with Paro were investigated. Compared with baseline readings, a significant increase in the ratio of urinary 17-ketosteroid:17-hydroxycorticosteroid (P<0.01), by week 4 of Paro being introduced, was found. The authors suggest this confers an improved physiological reaction to stress. A confounder noted was an increase in social interactions with other residents (P<0.05) by week 4, compared with baseline. It is also not clear from this study if Paro played any role in the increased sociability of residents; however, in the context of other studies on the topic, it seems likely.

These two studies do not provide much indication of the clinical use of SAR; however, they do give a direction for what future studies could investigate further.

Quantitative comparison

Several studies reported comparative quantitative data by using the same or similar assessment scales to others within their role category. The data from these studies have been reproduced from the studies and are compiled in tables 3–5. As different assessment tools were used across studies, a standardised mean score (0–100) was generated to allow comparison across similar assessment tools. Five comparable studies were identified in the affective therapy, each using a mood scale to assess either anxiety or depression or both, giving rise to seven comparable sets of data. Of these, five showed significant improvements in the mood scores either in the robot intervention group or in the follow-up score, depending on study design.

Four comparable studies were identified in the cognitive training set of studies, and of these, three studies showed significant improvements in the cognitive scores. Of note, the two phases of the Spanish paper25 have been listed as two separate sets of data as they are different studies with different interventions and different subject numbers; they both use the same control data, however, as seen on table 4.

Finally, three studies with comparable data were identified in the companionship set of studies, each of which used validated loneliness scales. All of these studies showed significant improvements in loneliness scores in the robot intervention group or in the follow-up score, depending on study design.

No comparative data were identified in the social facilitator or physiological therapy groups.