This randomized controlled trial aims to investigate the effects of cognitive task-based walking exercise on cognitive function, depressive symptoms, sleep quality, and quality of life in older adults experiencing brain fog. Eligible participants will be randomly assigned to either a cognitive task-based walking exercise group or a walking-only exercise group. The intervention will be conducted under physiotherapist supervision, three times per week for four weeks. Outcome measures will be assessed at baseline and after the intervention period to compare the effectiveness of the two exercise approaches.

This study is a single-center, prospective, randomized controlled trial designed to evaluate the effects of cognitive task-based walking exercise on cognitive function, depression, sleep quality, and quality of life in older adults experiencing brain fog. The study will be conducted between November 2025 and May 2026 at the Geriatrics Outpatient Clinic of Istanbul Medipol Mega Hospital.

Participants aged 65 years and older who report a subjective decline in attention, concentration, or mental clarity for at least four weeks and who demonstrate moderate or greater brain fog symptoms according to the Turkish version of the Brain Fog Scale will be eligible for inclusion. Only individuals with preserved global cognitive function (Montreal Cognitive Assessment score ≥20) and the ability to walk independently, with or without an assistive device, will be enrolled. Individuals with diagnosed neurological disorders, severe psychiatric conditions, or medical problems that limit physical activity will be excluded.

Eligible participants will be randomly assigned, using a computer-generated randomization sequence, to one of two groups: (1) a cognitive task-based walking exercise group or (2) a walking-only exercise group. Both groups will participate in supervised, low-intensity walking exercise sessions three times per week for four weeks. Exercise intensity and progression will be individualized according to each participant's physical capacity and balance status.

Each exercise session will include a warm-up phase, a main walking phase, and a cool-down phase. Participants in the cognitive task-based walking exercise group will be required to perform concurrent cognitive tasks during walking, including forward and backward counting, verbal fluency tasks, and sequencing of days of the week and months of the year, targeting attention, memory, and executive functions. The walking-only exercise group will follow the same walking protocol without the addition of cognitive tasks.

Outcome assessments will be conducted at baseline and after the four-week intervention period. Primary and secondary outcomes will include brain fog severity, cognitive function, depressive symptoms, sleep quality, and quality of life. All assessments will be performed by independent outcome assessors who are blinded to group allocation.

The findings of this study are expected to provide evidence regarding the clinical effectiveness of integrating cognitive tasks into walking exercise programs and to support holistic rehabilitation strategies in older adults with brain fog.

Inclusion Criteria:

• Aged 65 years or older
• Self-reported experience of brain fog symptoms (e.g., reduced attention, concentration, or -mental clarity) for at least the past 4 weeks
• Moderate or higher brain fog severity as determined by the Turkish version of the Brain Fog Scale
• Preserved global cognitive function (Montreal Cognitive Assessment score ≥20)
• Ability to walk independently, with or without an assistive device
• Ability to communicate verbally and follow instructions
• No changes in medication and no acute illness within the past 4 weeks
• Willingness to participate and provide written informed consent

Exclusion Criteria:

• Diagnosed neurodegenerative or neurological disorders (e.g., Alzheimer's disease, stroke, or other major neurological conditions)
• Severe psychiatric disorders
• Medical contraindications to physical exercise
• Severe visual or hearing impairments interfering with assessment or exercise participation
• Inability to adhere to or complete the study procedures and exercise program

De-identified individual participant data underlying the results reported in this study will be made available upon reasonable request to the corresponding author for scientifically sound research purposes. Data will be shared after approval of the proposed use and execution of an appropriate data sharing agreement, in accordance with institutional policies and applicable ethical requirements.

Beginning immediately following publication for a period of 5 years.

Researchers who provide a methodologically sound proposal may request access to the de-identified data. Requests should be directed to the corresponding author. Access will be granted after review and approval of the research proposal and completion of a data sharing agreement.

Outcome assessors will be independent from the intervention process and will be unaware of group assignments during baseline and post-intervention assessments.