The purpose of this study is to clarify the benefits to brain health and thinking processes that result from different forms of exercise. This study will examine the effectiveness of cybercycling (virtual reality enhanced stationary cycling) for persons at risk for and with MCI, and compare this with the individual cognitive, behavioral, and physiological effects of physical and mental exercise alone. The Investigators hypothesis that cognitive benefit will be greatest for combined aerobic and cognitive exercise compared to physical and mental exercise alone.

This is a multi-site, randomized controlled trial. Participants will be randomized into one of three conditions for six months: cybercycle-tour, cybercycle-game, or videogame alone. Comprehensive evaluations will include: neuropsychological (e.g., executive function and memory), behavioral (e.g., compliance and effort/watts), physiological (e.g., cardiorespiratory fitness), biomarker (e.g., BDNF), and an expanded neuroimaging pilot. After the six-month intervention period, participants choose whether or not to continue exercising, using any of the three conditions.

Inclusion Criteria:

• age 50+
• able to pedal recumbent stationary bicycle
• available for regular exercise participation 3-5x/week for at least 6 months
• physician permission to exercise

Exclusion Criteria:

• unstable heart condition or other significant cardiovascular history (e.g,. stroke)
• meets criteria for Alzheimer's or other dementia
• significant history of other neurological disease (e.g., seizures, Parkinson's, etc.)
• physician denial to exercise