Associations of sarcopenia and physical frailty in cognitive and affective (depression, apathy, and behavioral and psychological symptoms of dementia) functions of mild cognitive impairment (MCI) and Alzheimer's disease (AD) were not fully evaluated previously, especially not for gender differences. 165 AD, 84 MCI, and 48 control participants (175 female, 122 male) were evaluated for cognitive, affective, activities of daily living (ADL), and physical functions associated with sarcopenia and physical frailty. In both sexes, cognitive and affective functions, ADL, and physical functions worsened in MCI and AD compared to control subjects. Physical dysfunctions, especially slow gait speed (3 m up and go test), were significantly associated with cognitive, affective, and ADL declines in participants (control subjects, MCI, and AD) of each gender, which were especially noticeable in females. The present study may be the first to suggest significant associations of sarcopenia and physical frailty with cognitive and affective functions of MCI and AD, especially in females.