A Novel Multi-Modal Approach to Promote Functional Outcomes in Cognitively Frail Older Adults

Objectives: To compare the effects of intermittent theta burst stimulation (iTBS) primed with continuous theta burst stimulation (cTBS), nonpriming iTBS, and sham stimulation on top of aerobic exercise in terms of improving cognitive function, mobility, brain structure, and brain function in older adults with cognitive frailty.

Hypothesis to be tested: We hypothesize that iTBS primed with cTBS can maximize the induction of therapeutically beneficial metaplasticity, and that this will be reflected in improved brain structure and brain function, thereby enabling superior cognitive function and mobility improvement in older adults with cognitive frailty.

Design and subjects: A randomized controlled trial involving 60 older adults with cognitive frailty.

Study instruments: Transcranial magnetic stimulation (TMS) and magnetic resonance imaging (MRI).

Interventions: Participants will be randomly allocated to receive a 39-session intervention with different TBS protocols (i.e., cTBS+iTBS, sham cTBS+iTBS, and sham cTBS+sham iTBS), delivered 3 times per week for 3 months. All participants will receive 60 minutes of aerobic exercise after each stimulation session for 6 months.

Main outcome measures: comprehensive neuropsychological battery covering major executive function (i.e., selective attention/response inhibition, psychomotor speed, set shifting), working memory, and verbal fluency; (2) mobility function evaluated via SPPB, Timed-Up-and-GO (TUG) test, functional gait analysis (i.e., gait speed, gait variability).

Secondary outcomes: underlying neural mechanisms of intervention-induced benefits will be assessed via functional and structural magnetic resonance imaging.

Data analysis: Analysis of variance (ANOVA)

Inclusion criteria

• be between 60 and 90 years old;
• scored < 9/12 on the SPPB;
• scored >18/30 on the MoCA;
• scored >9/42 on the PFFS;
• lived in the community;
• be able to ambulate up to four meters with or without assistive devices;
• be able to provide written informed consent on their own behalf;
• can understand verbal and written Cantonese and/or English.

Exclusion criteria

• have magnetic resonance imaging (MRI) contraindications;
• have aerobic exercise contraindications;
• have transcranial magnetic stimulation contraindications;
• be diagnosed with neurodegenerative conditions (i.e., dementia, Parkinson's, Alzheimer's disease, Amyotrophic lateral sclerosis, and stroke);
• live in a nursing home or other care facilities/institutions;
• bed taking fixed dose of medication or had been taking medications known to potentially affect cognitive and physical function (e.g., psychotropic medications), as identified through a review of their medication lists recorded in the health software. Medications were categorized by properties (e.g., antipsychotics, antidepressants, etc.) to inform eligibility decisions.
• have a history indicative of carotid sinus sensitivity (i.e., falls due to loss of consciousness);
• cancer and undergo radiation therapy.