As we age, our bodies change in physical ways. One can expect a variety of changes to take place through the early- and middle-adult years. Each person experiences age-related changes based on many factors: biological factors such as molecular and cellular changes are called primary aging, while aging that occurs due to controllable factors, such as lack of physical exercise and poor diet, is called secondary aging.
Aging factors
As an individual progresses through adulthood, a variety of factors can affect the aging process. This includes primary factors like decline of cellular function and oxidative damage, and secondary factors like an unhealthy lifestyle.
Early Adulthood (Ages 20–40)
By the time we reach early adulthood, our physical maturation is complete, although our height and weight may increase slightly. In early adulthood, our physical abilities are at their peak, including muscle strength, reaction time, sensory abilities, and cardiac functioning. Most professional athletes are at the top of their game during this stage, and many women have children in the early-adulthood years.
The aging process, although not overt, begins during early adulthood. Around the age of 30, many changes begin to occur in different parts of the body. For example, the lens of the eye starts to stiffen and thicken, resulting in changes in vision (usually affecting the ability to focus on close objects). Sensitivity to sound decreases; this happens twice as quickly for men as for women. Hair can start to thin and become gray around the age of 35, although this may happen earlier for some individuals and later for others. The skin becomes drier and wrinkles start to appear by the end of early adulthood. The immune system becomes less adept at fighting off illness, and reproductive capacity starts to decline.
Middle Adulthood (Ages 40–65)
During middle adulthood, the aging process becomes more apparent. Around the age of 60, the eyes lose their ability to adjust to objects at varying distances, known as presbyopia. Most people between the ages of 40 and 60 will need some form of corrective lenses for vision deficits. Middle-aged adults are also at higher risk than younger adults for certain eye problems, such as glaucoma. Hearing also further declines: 14 percent of middle-aged Americans have hearing problems. Skin continues to dry out and is prone to more wrinkling, particularly on the sensitive face area. Age spots and blood vessels become more apparent as the skin continues to dry and get thinner. The muscle-to-fat ratio for both men and women also changes throughout middle adulthood, with an accumulation of fat in the stomach area.
Women experience a gradual decline in fertility as they approach the onset of menopause—the end of the menstrual cycle—around 50 years old. This process involves hormonal changes and may last anywhere from six months to five years. Because of the shifting hormone levels, women going through menopause often experience a range of other symptoms, such as anxiety, poor memory, inability to concentrate, depressive mood, irritability, mood swings, and less interest in sexual activity.