Lest the picture seem too rosy, young adults are not completely immune to the effects of aging. The closer they get to age 40, the more physical limitations they begin to notice. In fact, many young adults detect a significant decrease in energy and increase in health concerns after 40. However, with proper diet and exercise, the physical and psychological vitality that accompanies young adulthood can be maintained well into the 40s and beyond.
The most common health problems of young adulthood are arthritis, asthma, diabetes, depression and other mental problems, hypertension (high blood pressure), multiple sclerosis, and ulcers. Other conditions, such as atherosclerosis (hardening of the arteries), cirrhosis of the liver, heart and lung problems, kidney problems, and a variety of other diseases, may not exhibit symptoms at this stage, but may already be causing internal damage. Two additional categories of health concerns during young adulthood are disabilities and sexually transmitted diseases.
A physical disability is any physical defect, change, difficulty, or condition that has the potential to disrupt daily living. It may be present from birth, result from disease or injury, or develop later. A physical disability, for example, may be the absence of a vital organ from birth, deafness that develops in childhood, a spinal cord injury from a motorcycle accident, or a chronic condition like multiple sclerosis. The most common physical disabilities in adults are cerebral palsy, blindness, deafness, spinal cord injuries, and a number of chronic medical conditions, such as diabetes.
Persons who evidence subnormal intellectual functioning and social skills beginning before age 18 are developmentally disabled (mentally retarded). By definition, the developmentally disabled have an IQ of 70 or less and do not demonstrate culturally appropriate levels of social skills, living skills, responsibility, communication, and personal independence for their age.
Adults with a psychiatric disability (mental illness, or psychological disturbance) struggle with mild to incapacitating emotional problems and limitations that are often caused by either anxiety or affective disorders. Anxiety disorders are characterized by bouts of anxiety and/or panic. The recurrence of such episodes prompts an avoidance of people, places, and things. In many cases, the individual knows his or her anxiety is irrational, but is unable to master it. A combination of drug and psychological therapies can effectively treat anxiety disorders, which can otherwise severely disrupt life activities.
Affective disorders (mood disorders) cause a person to experience abnormally high and/or low feelings. Although several types of mood disorders exist, the two most common are unipolar depression, marked by feelings of self‐blame, sadness, guilt, and apathy; and bipolar disorder (manic‐depressive), marked by alternating periods of depression and mania (extreme hyperactivity and elation). Most affective disorders are treatable with a combination of medications and counseling. Unipolar depression responds well to antidepressant medications; bipolar disorder, to lithium carbonate.
Sexually transmitted diseases
Certain sexually transmitted diseases (STDs) are caused by microscopic single‐cell organisms known as bacteria. These organisms invade cells of the body, causing infection and disease. The most common bacterial STDs are gonorrhea, nongonococcal urethritis, nongonococcal cervicitis, chlamydia, and syphilis. Other STDs are caused by viruses — noncellular, microscopic particles that replicate themselves within invaded cells. Antibiotic medications are ineffective against them, making viruses very difficult or impossible to eliminate. The most common viral STDs are herpes, genital warts, and human immunodeficiency virus (HIV).
HIV is the virus that causes acquired immunodeficiency syndrome (AIDS). HIV does not directly cause death; rather it depresses the immune system of a victim to the point that infection and disease overwhelm the body's natural defenses. For HIV to attack human cells, it must first attach itself to special receptors on the cells' surface. Through several complex chemical reactions, cells attacked by HIV become factories that produce more viruses, which in turn attack more cells, which in turn become factories, and so on. Eventually the immune system becomes so depressed that almost any disease can easily overwhelm bodily defenses.
Based on medical research, HIV appears to be spread through the exchange of body fluids (blood, vaginal secretions, and semen), not through casual contact. The following are the most probable means of transmitting and contracting HIV: