The investigators will conduct a proof-of-concept randomized controlled trial study to provide preliminary evidence of efficacy of a resistance exercise training program for maintaining white matter health and improving cognitive function in older adults with vascular cognitive impairment, defined as the presence of cognitive impairment combined with cerebral small vessel disease, compared with a stretch and relaxation program.

A total of 88 adults with vascular cognitive impairment will be randomized to either a 12-month twice-weekly resistance training program or stretch and relaxation program. There will be three measurement sessions: baseline, 6 months (midpoint of intervention period), and 12 months (end of intervention period).

Inclusion Criteria:

The study will specifically recruit individuals who fulfill the diagnostic criteria for SIVCI -- the presence of both cognitive impairment and small vessel ischaemic disease.

Specifically, individuals must meet the following inclusion criteria:

1. Montreal Cognitive Assessment (MoCA) score less than 26 at screening;
2. MMSE score of = or > 20 at screening;
3. Community-dwelling;
4. Lives in Metro Vancouver;
5. Able to comply with scheduled visits, treatment plan, and other trial procedures;
6. Must be able to read, write, and speak English in which psychometric tests are provided with acceptable visual and auditory acuity;
7. Stable on a fixed dose of cognitive medications (e.g., donepezil, galantamine, rivastigmine, memantine, etc.) that is not expected to change during the 12-month study period, or, if they are not on any of these medications, they are not expected to start them during the 12-month study period;
8. Provide a personally signed and dated informed consent document indicating that the individual (or a legally acceptable representative) has been informed of all pertinent aspects of the trial. In addition, an assent form will be provided at baseline and again at regular intervals;
9. Able to walk independently; and
10. Must be in sufficient health to participate in study's aerobic-based exercise training program. This will be based on medical history, vital signs, physical examination by study physicians, and written recommendation by family physician indicating individual's appropriateness to participate in an aerobic-based exercise training program.

Exclusion Criteria:

1. Absence of relevant small vessel ischaemic lesions on an existing brain computed tomography (CT) or MRI;
2. Diagnosed with another type of dementia (e.g., AD) or other neurological conditions (e.g., multiple sclerosis, Parkinson's disease, etc.) that affects cognition and mobility;
3. Diagnosed previously with a genetic cause of SIVCI (e.g., CADASIL);
4. At high risk for cardiac complications during exercise and/or unable to self-regulate activity or to understand recommended activity level (i.e., Class C of the American Heart Risk Stratification Criteria);
5. Participating in regular RT in the last six months;
6. Have clinically significant peripheral neuropathy or severe musculoskeletal or joint disease that impairs mobility;
7. Taking medications that may negatively affect cognitive function, such as anticholinergics, including agents with pronounced anticholinergic properties (e.g., amitriptyline), major tranquilizers (typical and atypical antipsychotics), and anticonvulsants (e.g., gabapentin, valproic acid, etc.); or
8. Individual who plans to participate or is enrolled in a clinical drug trial concurrent to this study.
9. Unable to meet the specific scanning requirements of the UBC 3T MRI Research Centre. Specifically, we will exclude anyone with: pacemaker, brain aneurysm clip, cochlear implant, recent surgery or tattoos within the past 6 weeks, electrical stimulator for nerves or bones, implanted infusion pump, history of any eye injury involving metal fragments, artificial heart valve, orthopedic hardware, other metallic prostheses, coil, catheter or filter in any blood vessel, ear or eye implant, bullets, or other metallic fragments.