Provided by David Satcher, M.D., Ph.D.
Surgeon General of the United States of America
Chapter 2
Overview of Mental Illness
Mental illness is a term rooted in history that refers
collectively to all of the diagnosable mental disorders. Mental disorders are
characterized by abnormalities in cognition, emotion or mood, or the highest
integrative aspects of behavior, such as social interactions or planning of
future activities. These mental functions are all mediated by the brain. It is,
in fact, a core tenet of modern science that behavior and our subjective mental
lives reflect the overall workings of the brain. Thus, symptoms related to
behavior or our mental lives clearly reflect variations or abnormalities in
brain function. On the more difficult side of the ledger are the terms disorder,
disease, or illness. There can be no doubt that an individual with schizophrenia
is seriously ill, but for other mental disorders such as depression or
attention-deficit/hyperactivity disorder, the signs and symptoms exist on a
continuum and there is no bright line separating health from illness, distress
from disease. Moreover, the manifestations of mental disorders vary with age,
gender, race, and culture. The thresholds of mental illness or disorder have,
indeed, been set by convention, but the fact is that this gray zone is no
different from any other area of medicine. Ten years ago a serum cholesterol of
200 was considered normal. Today, this same number alarms some physicians and
may lead to treatment. Perhaps every adult in the United States has some
atherosclerosis, but at what point does this move along a continuum from normal
into the realm of illness? Ultimately, the dividing line has to do with severity
of symptoms, duration, and functional impairment.
Despite the existence of a gray zone between health and illness, science can
study the mechanisms by which illness occurs. Indeed, understanding mood
regulation and its abnormalities, for example, proceeds independently from any
set of diagnostic clinical criteria. Family studies, molecular genetics
strategies, epidemiology, and the tools of clinical investigation tailored to
specific populations are being used to investigate the mechanisms of mental
illness. Specific manifestations of mental illness will be covered in succeeding
pages.
This overview of mental illness focuses on those features of the disease process
that are most common and characteristic of these disorders. The chapters that
follow will present specific details about major categories of mental disorders
that occur across the life span. The purpose here is to provide a framework upon
which subsequent discussions of specific disorders can rest. The section leads
with a descriptive overview of the cardinal manifestations, signs, and symptoms
of mental disorders. It then describes how mental disorders are diagnosed and
classified and provides an overview of the epidemiology and societal burden of
mental disorders.
Back to the Mental Health: The Surgeon General's Report Table of Contents