Previous research has found improvements in motor and cognitive measures following Assisted Cycle Therapy (AC) in adolescence with Down syndrome (DS). Our study investigated whether we would find improvements in mental health in older adults with DS as measured from the Adapted Behavior Dementia Questionnaire (ABDQ), Physical Activity Self Efficacy Scales (PACES), Children's Depressive inventory, which are early indicators of Alzheimer's disease (AD) in persons with Down syndrome. This study consisted of seven participants with Down syndrome between the ages of 31 and 54, inclusive, that cycled for 30 minutes 3 x/week for eight weeks either at their voluntary cycling rate (VC) or approximately 35% faster with the help of a mechanical motor (ACT). Our results were consistent with our prediction that self efficacy improved following ACT, but not VC. However, our results were not consistent with our prediction that dementia and depression were improved following ACT more than VC. These results were interpreted with respect to the effects of exercise in older adults with DS. Future research should focus on recruiting more participants, especially those with deficits in mental health.