h care system is enormous. As cognitive abilities and functional capacity deteriorate, negative emotional, social, and behavioral outcomes occur. In the early stages, social and emotional withdrawal is common. Many Alzheimer's disease patients demonstrate anxiety and depression as well, which result in more behavioral problems and increased limitations in daily activities. By 2030, the percentage of people with neurocognitive disorders in the United States is expected to reach 65 million, with associated increases in health care costs. Neurocognitive disorder also affects family caregivers, who are at increased risk themselves for depression and anxiety. Until recently, our thinking has been dominated by the ideas of mind-body dualism. According to this view, mind and body function independently, although they may interact. This philosophy persisted for many centuries with significant efforts to identify biological causes for medical illness and a relative neglect of attention to psychological variables influencing physical health. Only recently psychology has begun to have a role in identifying and treating medical illness. At present, psychologists play important roles in prevention, treatment, or management of physical health problems. Gradually, psychologists found certain personality patterns related to specific medical illnesses. Now, the bio-psycho-social model of physical illness recognizes the contributions of body, mind, and the social environment to the development of illness Any negative emotional experience that is accompanied by biochemical, physiological, cognitive, and behavioral responses that attempt to change or adjust to the stressor. A stressor is any agent that produces tension or another negative emotion such as fear and prepares the organism for a fight-or-flight response. Stressors can be physical (such as a medical disease or physical injury), environmental (natural disaster, change in living situation), interpersonal-social (breakup of a relationship, argument with a family member), or psychological (having to pay a debt). Stress is more likely if an event has a negative outcome, but even some positive outcomes (such as a higher paying job with more responsibilities) can also cause stress. Stress occurs when an event is perceived as uncontrollable, unpredictable, or ambiguous. People react to stressors in a variety of ways The study of relations among social, psychological, and physical responses. People who are under severe and/or chronic stress are
more likely to catch a cold, develop an upper respiratory infection, or get the flu. Stress suppresses the ability of the immune system to function adequately and increases people's susceptibility to bacteria and viruses. When people are under stress, wounds heal more slowly, chronic diseases progress more rapidly, and vaccinations are less effective. People or animals under stress develop fewer antibodies following immunization for flu, hepatitis, and tetanus. Interpersonal interactions also affect cell activity and immune functioning. Hostility between spouses, for example, is associated with suppressed immune functioning. Loneliness and perceived social isolation are also associated with poor immune functioning. Happily married men have the best immune functioning.
The variables that affect how stress is experienced and how it affects health and other aspects of functioning. Personality traits are related to stress. As stated before, Type A personality (consistent striving for achievement, impatience and time urgency, and aggressiveness towards others) is
influenced more by stress than Type B personality (easy-going, flexible, and non-aggressive). Type A persons are usually keyed up and have difficultly relaxing. Persons who are hostile and angry, even if they do not have the full Type A pattern, have an increased risk for cardiovascular problems. Negative emotions and/or a pessimistic style have been linked to poorer immune functioning. Optimists, on the other hand, are sick less often and have lower blood pressure. One of the most important pr