Another excerpt from the US Office of Surgeon General:
http://www.surgeongeneral.gov/library/mentalhealth/chapter1/sec1.html#roots_stigma
Mind and Body are Inseparable
Considering health and illness as points along a continuum helps one appreciate that neither state exists in pure isolation from the other. In another but related context, everyday language tends to encourage a misperception that “mental health†or“mental illness†is unrelated to“physical health†or“physical illness.†In fact, the two are inseparable.
Seventeenth-century philosopher Rene Descartes conceptualized the distinction between the mind and the body. He viewed the “mind†as completely separable from the “body†(or“matter†in general). The mind (and spirit) was seen as the concern of organized religion, whereas the body was seen as the concern of physicians (Eisendrath & Feder, in press). This partitioning ushered in a separation between so-called“mental†and“physical†health, despite advances in the 20th century that proved the interrelationships between mental and physical health (Cohen & Herbert, 1996; Baum & Posluszny, 1999).
Although“mind†is a broad term that has had many different meanings over the centuries, today it refers to the totality of mental functions related to thinking, mood, and purposive behavior. The mind is generally seen as deriving from activities within the brain but displaying emergent properties, such as consciousness (Fischbach, 1992; Gazzaniga et al., 1998).
One reason the public continues to this day to emphasize the difference between mental and physical health is embedded in language. Common parlance continues to use the term“physical†to distinguish some forms of health and illness from“mental†health and illness. People continue to see mental and physical as separate functions when, in fact, mental functions (e.g., memory) are physical as well (American Psychiatric Association, 1994). Mental functions are carried out by the brain. Likewise, mental disorders are reflected in physical changes in the brain (Kandel, 1998). Physical changes in the brain often trigger physical changes in other parts of the body too. The racing heart, dry mouth, and sweaty palms that accompany a terrifying nightmare are orchestrated by the brain. A nightmare is a mental state associated with alterations of brain chemistry that, in turn, provoke unmistakable changes elsewhere in the body.
Instead of dividing physical from mental health, the more appropriate and neutral distinction is between “mental†and “somatic†health. Somatic is a medical term that derives from the Greek word soma for the body. Mental health refers to the successful performance of mental functions in terms of thought, mood, and behavior. Mental disorders are those health conditions in which alterations in mental functions are paramount. Somatic conditions are those in which alterations in nonmental functions predominate. While the brain carries out all mental functions, it also carries out some somatic functions, such as movement, touch, and balance. That is why not all brain diseases are mental disorders. For example, a stroke causes a lesion in the brain that may produce disturbances of movement, such as paralysis of limbs. When such symptoms predominate in a patient, the stroke is considered a somatic condition. But when a stroke mainly produces alterations of thought, mood, or behavior, it is considered a mental condition (e.g., dementia). The point is that a brain disease can be seen as a mental disorder or a somatic disorder depending on the functions it perturbs.