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What is Comorbidity?
When two disorders or illnesses occur in the same
person, simultaneously or sequentially, they
are called comorbid. Comorbidity also implies
interactions between the illnesses that affect the course and
prognosis of both.
Is Drug Addiction
a Mental Illness?
Yes, because addiction changes
the brain in fundamental ways,
disturbing a person's normal hierarchy
of needs and desires and
substituting new priorities connected
with procuring and using
the drug. The resulting compulsive
behaviors that override the ability
to control impulses despite the
consequences are similar to hallmarks
of other mental illnesses.
Addiction
changes the
brain, disturbing
the normal
hierarchy of
needs and desires.
In fact, the Diagnostic and
Statistical Manual of Mental
Disorders (DSM), the definitive
resource of diagnostic criteria for all mental disorders, includes
criteria for drug use disorders,
distinguishing between two types:
drug abuse and drug dependence.
Drug dependence is synonymous
with addiction. By comparison,
the criteria for drug abuse hinge
on the harmful consequences of
repeated use but do not include
the compulsive use, tolerance (i.e.,
needing higher doses to achieve
the same effect), or withdrawal
(i.e., symptoms that occur when
use is stopped) that can be signs
of addiction.
Childhood ADHD
and Later Drug
Problems
Numerous studies have documented
an increased risk for
drug use disorders in youth with
untreated ADHD, although some
suggest that only a subset of
these individuals are vulnerable:
those with comorbid conduct
disorders. Given this linkage, it is
important to determine whether
effective treatment of ADHD
could prevent subsequent drug
abuse and associated behavioral
problems. Treatment of childhood
ADHD with stimulant medications
such as methylphenidate or amphetamine
reduces the impulsive
behavior, fidgeting, and inability
to concentrate that characterize
ADHD. However, some physicians
and parents have expressed concern
that treating childhood ADHD
with stimulants might increase a
child's vulnerability to drug abuse
later in life. Recent reviews of
long-term studies of children with
ADHD who received stimulant
therapy found no evidence for
this increase. However, most of
these studies have methodological
limitations, including small sample
sizes and nonrandomized study
designs, indicating that more
research is needed, particularly
in adolescents.
How Common
Are Comorbid
Drug Use and
Other Mental
Disorders?
Many people who regularly abuse
drugs are also diagnosed with
mental disorders and vice versa.
The high prevalence of this comorbidity
has been documented
in multiple national population
surveys since the 1980s. Data
show that persons diagnosed with
mood or anxiety disorders were
about twice as likely to suffer also
from a drug use disorder (abuse
or dependence) compared with
respondents in general. The same
was true for those diagnosed with
an antisocial syndrome, such as
antisocial personality or conduct
disorder. Similarly, persons diagnosed
with drug disorders were
roughly twice as likely to
suffer also from mood and
anxiety disorders ("Overlapping Conditions–
Shared Vulnerability").
Gender is also a factor in the
specific patterns of observed comorbidities.
For example, the
overall rates of abuse and dependence
for most drugs tend to be
higher among males than females,
and males are more likely to suffer
also from antisocial personality
disorder. In contrast, women
have higher rates of amphetamine
dependence and higher rates of
mood and anxiety disorders.
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