Diagnosis

Type of psychology: All
Fields of study: All
Diagnosis is a process whereby an assessor evaluates symptoms and signs of illness or
abnormality in order to be able to determine the type of problem present. This can be
done using interviews, observation, and formal testing instruments or procedures.
Key concepts
• assessment
• associated features
• course
• criteria
• differential diagnosis
• interviewing
• screening
• signs
• symptoms
The word “diagnosis” is derived from two Greek roots: dia, which means “to
distinguish,” and gnosis, which means “knowledge.” It is most often understood
to be a noun, but from the perspective of a psychologist or a person
assessing an afflicted individual, it is seen as a process whereby one understands
the condition of the person affected. It is also important to remember
that diagnosis is not a one-time event but is ongoing. For example, diagnoses
may shift. Changes can be noted in terms of signs (the observable
indications of mental health problems) and symptoms (the problems reported
by clients indicating their discomfort, notice of changes, or abnormality
in their way of being). In some ways, diagnosis has no discrete end but
consists of different observation points in time when the progress of a disorder
is evaluated.

Screening
The goal of diagnosis is to arrive at information that can be communicated
and used to aid in the treatment of the person with the mental or physical
health problem. In the United States, mental health diagnoses are typically
based on the framework presented in the American Psychiatric Association’s
Diagnostic and Statistical Manual of Mental Disorders (DSM), which is updated
periodically. In order to be diagnosed with a particular mental disorder,
individuals go through a systematic evaluation to determine whether
they satisfy the diagnostic criteria, the conditions necessary to qualify for a
disorder, as described in the DSM.

Often, this process begins when individuals or their relatives notice symptoms
and seek the consultation of a professional. At that time, the professional
will begin a series of systematic inquiries, ruling possible conditions in and out of consideration, in order to determine how best to proceed with
further diagnostic work. In some cases, a preliminary step called screening
may be undertaken. Screening is a relatively brief procedure in which the
signs and symptoms that have the highest association with specific mental
health conditions are asked about in order to determine whether a more
thorough evaluation is necessary.

Typically, screening results in a person being placed into one of two categories:
possibly having the condition of concern or mostly likely not having
the condition. Those individuals in the former category receive more thorough
evaluations. Those who are judged as unlikely to have the condition
do not receive more thorough evaluations immediately but instead may be
invited to continue their own observations of symptoms or to begin another
path of diagnostic inquiry.

For those performing the screening, the primary goal is to identify those
individuals who may have the problem. It is also important, however, not to
rule out individuals for further evaluation who might actually have the condition
but do not appear to do so during the screening. In technical terms,
the first group is known as true positives: individuals who are screened as
likely to have the condition and who actually have it. The second group is
known as false negatives: individuals who are screened as not having the
condition but actually do have it.

Screening tests increase in their usefulness if they are not overly sensitive
and do not produce too many false positives: people who screen positive but
who actually do not have the condition. It is important to minimize false
positives because some diagnostic procedures, such as magnetic resonance
imaging (MRI), are expensive. Additionally, some diagnostic procedures
can be invasive, such as injection dye procedures used to observe different
organ systems in action. Minimizing false positives in screening saves money
for health care providers and, more important, saves potential pain, suffering,
and anxiety for individuals.

Finally, screening also increases in usefulness when it can effectively identify
true negatives: individuals who are screened as not having the problem
and who, in fact, do not. The sooner these individuals are identified, the
more quickly they can be considered for other diagnostic possibilities.