1. Noticeable signs of aging like wrinkles, gray hair, and decreased muscle strength begin to appear in middle adulthood starting in the 40s. 2. Physical changes include weight gain, decreased bone density and vision changes. Hearing and cardiovascular functioning also gradually decline. 3. Hormonal changes impact sexuality and fertility. Menopause occurs in late 40s/early 50s ending menstruation and reducing estrogen levels in women. Testosterone levels slowly decrease in men. 4. While fluid intelligence declines, crystallized intelligence increases with experience. Memory functioning remains stable if effective strategies are used. Job satisfaction is high during middle adulthood.