Understanding Psychology (10th Ed)

emerging adulthood
The period 
beginning in the late teenage years and 
extending into the mid-20s.
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Module 39 
Adulthood 
423
Physical Development: 
The Peak of Health
For most people, early adulthood marks the peak of physical health. From about 18 
to 25 years of age, people’s strength is greatest, their refl exes are quickest, and their 
chances of dying from disease are quite slim. Moreover, reproductive capabilities are 
at their highest level. 
Around age 25, the body becomes slightly less effi cient and more susceptible to 
disease. Overall, however, ill health remains the exception; most people stay remark-
ably healthy during early adulthood. (Can you think of any machine other than the 
body that can operate without pause for so long a period?) 
During middle adulthood, people gradually become aware of changes in their 
bodies. They often experience weight gain (although they can avoid such increases 
through diet and exercise). Furthermore, the sense organs gradually become less 
sensitive, and reactions to stimuli are slower. But generally, the physical declines 
that occur during middle adulthood are minor and often unnoticeable (DiGiovanna, 
1994). The major biological change that does occur during middle adulthood per-
tains to reproductive capabilities. On average, during their late 40s or early 50s, 
women begin  menopause,  during which they stop menstruating and are no longer 
fertile. Because menopause is accompanied by a signifi cant reduction in the pro-
duction of estrogen, a female hormone, women sometimes experience symptoms 
such as hot fl ashes, sudden sensations of heat. Many symptoms can be treated 
through hormone therapy (HT) in which menopausal women take the hormones 
estrogen and progesterone.

However, hormone therapy poses several dangers, such as an increase in the 

risk of breast cancer, blood clots, and coronary heart disease. These uncertainties 
make the routine use of HT controversial. Currently, the medical consensus seems 
to be that younger women with severe menopausal symptoms ought to consider