Impact of action observation therapy on motor and cognitive outcomes in older adults with mild cognitive impairment: a randomized controlled study

Mild cognitive impairment (MCI) is characterized by cognitive deficits beyond age- and education-expected levels without major ADL impairment or dementia, often with predominant memory deficits. Globally, cognitive impairment among older adults is projected to rise substantially, posing societal challenges. MCI commonly affects executive function, leading to reduced mobility and independence in ADLs, and is linked to upper limb motor impairments and gait/balance dysfunctions, increasing fall risk. Interventions combining physical and cognitive training may mitigate these deficits. Action Observation Therapy (AOT) involves observing a motor action and imitating it, engaging the mirror neuron system (MNS), which may enhance motor learning and cognitive functions. While AOT has shown benefits in stroke and MCI populations, uncertainty remains regarding optimal observation modality (therapist vs. peer) in older adults with MCI. This study investigates whether AOT improves cognition, UL function, ADLs, gait, and balance, and whether therapist vs. peer observation yields differential effects.

Prior work indicates MCI negatively impacts motor control and ADLs, with strong ties between cognitive function and UL performance, as well as gait and balance impairments that elevate fall risk. AOT has demonstrated efficacy in stroke rehabilitation, improving UL function and independence in ADLs, and shows promise in MCI populations. The MNS, activated during both action execution and observation, underpins motor learning and may benefit cognitive domains like attention and memory. Age- and sex-related differences in MNS activation suggest demographic factors could modulate AOT efficacy. In pediatric cerebral palsy, peer observation sometimes outperforms therapist observation, suggesting relatability may influence learning; however, these findings may not generalize to older adults with MCI due to different neurocognitive profiles. Evidence also supports community and group-based AOT/exercise programs for enhancing functional outcomes in older adults, emphasizing feasibility and dosage considerations.

Study design: Randomized, block-structured, analytical, longitudinal experimental study conducted in three senior care facilities in Madrid, Spain. Ethical approval: Hospital Clínico San Carlos (code: 23/122-E). Trial registration: NCT05934344. Standards: CONSORT and Helsinki guidelines followed. Participants: Adults ≥65 years with MCI (MoCA 20–26), able to walk independently for 10 m, and without severe pain. Exclusion: Uncorrected sensory impairments (without aids), inability to follow simple commands, recent neurological/musculoskeletal conditions, or exercise contraindications. Recruitment: Healthcare staff screened residents to minimize selection bias; informed consent obtained. Randomization: OxMaR software ensured allocation concealment and balanced assignment to three groups: Therapist Observation Group (TOG), Peer Observation Group (POG), and Control Group (CG). Attrition: Of 44 eligible, 36 randomized (TOG n=11, POG n=15, CG n=10); final analyzed n=30 with 6 dropouts (1 pre-intervention in TOG; 5 lost to follow-up in POG). Intention-to-treat (ITT) and sensitivity analyses conducted. Intervention: Duration 5 weeks, 3 sessions/week, 20–30 minutes/session. TOG observed exercises demonstrated by a therapist positioned in front; POG observed cognitively intact peers performing the same exercises; CG continued standard facility therapy focused on maintaining mobility and ADLs. Exercises included resistance training, balance activities, and UL exercises, inspired by Fugl-Meyer Assessment (FMA) and Vivifrail programs, tailored to individual deficits based on baseline assessments. Outcome measures: Cognition—MoCA; ADLs—Barthel Index (BI); UL function—Fugl-Meyer Assessment Upper Extremity (FMA-UE), Box and Block Test (BBT); Balance—Berg Balance Scale (BBS); Functional mobility—Timed Up and Go (TUG); Gait speed—10-Meter Walk Test at normal pace (10MWTN) and fast pace (10MWTF). Assessments conducted pre- and post-intervention; improvement variables computed as post minus pre. Data analysis: Sample size via GRANMO based on Donoghue et al., targeting minimum detectable difference of 6.3 (α=0.05, β=0.2) with 20% dropout. Normality assessed with Shapiro–Wilk (non-normal distribution). Between-group differences tested with Kruskal–Wallis; pairwise post-hoc with Mann–Whitney U. Significance p<0.05. Effect sizes computed with Cohen’s d (small 0.2, medium 0.5, large 0.8) to interpret clinical relevance. Analyses performed in SPSS v29.0.

Baseline: Groups were homogeneous in age, gender, and initial scores (MoCA, BI, FMA-UE, BBT, BBS, TUG, 10MWTN, 10MWTF). Kruskal–Wallis (improvement variables): MoCA H=13.3, p=0.001; BI H=7.0, p=0.030; FMA H=17.2, p<0.001; BBT left H=8.7, p=0.013; BBT right H=3.7, p=0.160 (ns); BBS H=16.2, p<0.001; TUG H=15.7, p<0.001; 10MWTN H=16.6, p<0.001; 10MWTF H=8.6, p=0.013. Pairwise comparisons (median improvement, IQR; Mann–Whitney U with p-values; effect sizes where available): - TOG vs POG: No significant differences across outcomes (MoCA p=0.97; BI p=0.83; FMA p=0.53; Left BBT p=0.97; Right BBT p=0.68; BBS p=0.97; TUG p=0.70; 10MWTN p=0.11; 10MWTF p=0.36). - TOG vs CG: Significant improvements in MoCA (p<0.001, d=1.51), BI (trend, p=0.13, ns), FMA (p<0.001, d=3.44), Left BBT (p=0.002, d=2.16), Right BBT (p=0.04, d=1.34), BBS (p<0.001, d=2.72), TUG (p<0.001, d=−1.92), 10MWTN (p=0.001, d=−1.05), 10MWTF (p=0.019, d=−0.82). - POG vs CG: Significant improvements in MoCA (p=0.004, d=1.77), FMA (p<0.001, d=1.34), BBS (p=0.001, d=1.94), TUG (p<0.001, d=−1.71), 10MWTN (p<0.001, d=−1.18), 10MWTF (p=0.009, d=−1.22); BI (p=0.063, ns); Right BBT (p=0.315, ns); Left BBT (p=0.05, borderline). Medians (improvement): MoCA TOG 2.5 (1.0,4.0), POG 2.5 (1.25,3.75), CG 0.0 (−0.5,0.5); BI TOG 2.5 (−0.62,6.87), POG 2.5 (0.0,5.0), CG 0.0 (0.0,0.0); FMA TOG 23.5 (17.62,29.37), POG 29.0 (9.12,48.87), CG 1.0 (−1.12,5.37); BBS TOG 8.5 (6.0,11.0), POG 9.0 (4.87,13.12), CG 0.0 (−1.62,1.62); TUG TOG −5.8 (−8.4,−3.2), POG −5.1 (−7.63,−2.57), CG −0.34 (−1.13,1.25); 10MWTN TOG −2.2 (−3.74,0.88), POG −3.08 (−5.18,−0.98), CG −0.4 (−0.95,0.15); 10MWTF TOG −1.15 (−2.0,0.5), POG −1.7 (−2.58,−0.82), CG −0.145 (−0.98,1.52). Overall: Both AOT groups (TOG, POG) exhibited significant gains over CG in cognition (MoCA), UL function (FMA; some BBT contrasts), balance (BBS), mobility (TUG), and gait speed (10MWT normal/fast). No significant differences between TOG and POG on any outcome.

AOT administered three times weekly for five weeks produced significant improvements in cognition, UL motor function, balance, mobility, and gait speed in older adults with MCI compared to standard care. The absence of differences between therapist and peer observation suggests that both modalities effectively engage the mirror neuron system and support motor learning and cognitive enhancement in this population. While ADL gains (BI) trended positively in intervention groups, BI may lack sensitivity to detect subtle functional changes in MCI. The strongest effects were seen in FMA and BBS, consistent with targeted UL and balance training embedded within AOT sessions and prior literature on AOT efficacy. Improvements in 10MWT and TUG indicate enhanced functional mobility and dynamic balance, even without specific speed-focused drills, likely reflecting better balance, motor control, and fatigue resistance. Contrary to pediatric CP findings favoring peer models, older adults with MCI may benefit equally—or slightly more—from expert demonstrations, potentially due to factors like cognitive fatigue, variability in peer performance, and the need for structured, clear guidance. Group-based AOT is feasible and potentially cost-effective, with peer-facilitated models meriting optimization to ensure safety, engagement, and fidelity.

AOT is an effective and adaptable intervention for improving motor and cognitive outcomes in older adults with MCI. Both therapist- and peer-observation modalities yielded significant benefits compared to standard care across cognition, balance, mobility, and gait domains. These findings support integrating AOT into rehabilitation programs for MCI, with future research needed to validate results in larger samples, assess long-term sustainability, and refine peer-based delivery models.

Small sample size limits generalizability; lack of long-term follow-up precludes conclusions about durability of effects; Barthel Index may be insufficiently sensitive to subtle ADL changes in MCI; potential influences of cognitive fatigue and age-related variability in peer observation were not systematically controlled; outcomes rely on short-term pre/post measures without extended retention assessment.