The mind and body interact in powerful ways that affect a person's health. The digestive system Overview of the Digestive System The digestive system, which extends from the mouth to the anus, is responsible for receiving food, breaking it down into nutrients (a process called digestion), absorbing the nutrients into... read more is profoundly controlled by the mind (brain), and anxiety, depression, and fear dramatically affect the function of this system. Social and psychologic stress can trigger or aggravate a wide variety of diseases and disorders, such as diabetes mellitus Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Urination and thirst are... read more , high blood pressure High Blood Pressure High blood pressure (hypertension) is persistently high pressure in the arteries. Often no cause for high blood pressure can be identified, but sometimes it occurs as a result of an underlying... read more , and migraine headache Migraines A migraine headache is typically a pulsating or throbbing pain that ranges from moderate to severe. It can affect one or both sides of the head. It is often worsened by physical activity, light... read more . However, the relative importance of psychologic factors varies widely among different people with the same disorder.
Most people, on the basis of either intuition or personal experience, believe that emotional stress can cause or alter the course of even major physical diseases. How these stressors do this is not clear. Emotions obviously can affect certain body functions, such as heart rate, blood pressure, sweating, sleep patterns, stomach acid secretion, and bowel movements, but other relationships are less obvious. For example, the pathways and mechanisms by which the brain and immune system interact are only beginning to be identified. It is remarkable that the brain can alter the activity of white blood cells and thus an immune response because white blood cells travel through the body in blood or lymph vessels and are not attached to nerves. Nevertheless, research has shown that the brain does communicate with the white blood cells. For example, depression Depression A short discussion of prolonged grief disorder. Depression is a feeling of sadness and/or a decreased interest or pleasure in activities that becomes a disorder when it is intense enough to... read more may suppress the immune system and make a person more susceptible to infections such as the common cold.
Stress can cause physical symptoms even though no physical disease may be present because the body responds physiologically to emotional stress. For example, stress can cause anxiety Overview of Anxiety Disorders Anxiety is a feeling of nervousness, worry, or unease that is a normal human experience. It is also present in a wide range of psychiatric disorders, including generalized anxiety disorder,... read more , which then triggers the autonomic nervous system Overview of the Autonomic Nervous System The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person’s conscious... read more and hormones such as epinephrine to speed up the heart rate and to increase the blood pressure and the amount of sweating. Stress can also cause muscle tension, leading to pain in the neck, back, head, or elsewhere.
The mind-body interaction is a two-way street. Not only can psychologic factors contribute to the onset or aggravation of a wide variety of physical disorders, but also physical diseases can affect a person's thinking or mood. People with life-threatening, recurring, or chronic physical disorders commonly become depressed. The depression may worsen the effects of the physical disease and add to a person's misery.