Co-morbidity in ADHD
When diseases tend to occur together more often than chance would predict,
it is called comorbidity. A familiar example is Diabetes and high blood
pressure. Identifying comorbid conditions when ADHD is present has led to
better treatments and a far better understanding of child psychiatry. When a
child is assessed for ADHD, it is absolutely essential to see if any of the
other common comorbid disorders are present. The presence of these comorbid
problems predicts which treatments will work and what the long term
prognosis is. About 50% of children have ADHD plus some other disorder. Here
is a brief description of the common disorders comorbid with ADHD. Virtually
all the child hood psychiatric disorders are more common in ADHD. Girls tend
to have more comorbid disorders than boys. ADHD without hyperactivity
differs here. There is no increase for that disorder in Conduct disorder or
Oppositional defiant disorder.
Conduct disorder
This is an inherited disorder characterized by cruelty, violence, and
disregard for the rights of others. When it is present with ADHD, it is a
bad sign. Approximately 25% of ADHD children also have this. Children and
adolescents with ADHD without hyperactivity do not have an increase in
Conduct disorder. A third of ADHD children who also have conduct disorder
will have committed multiple crimes by the time their teenage years are over
compared to 3-4% of children who have only ADHD. Children with ADHD and
Conduct disorder have a higher rate of becoming criminals as adults, too.(8)
Oppositional Defiant Disorder
This is a disorder characterized by aggression, bad temper tantrums, and a
desire to irritate and oppose others. About 80% of children with this also
have ADHD. Children and adolescents with ADHD without hyperactivity do not
have an increase in Oppositional Defiant disorder.
Tic disorders
Sudden movements of the body or sudden sounds which are not voluntary are
characteristic of Tourette's and related problems. ADHD and tics often go
together. Tics certainly change the treatment of ADHD.
Anxiety Disorders
Anxiety disorders are not uncommon in children, but ADHD children are twice
as likely to have them. One-third of ADHD children have anxiety disorders.
They predict school failure and strongly influence the treatment of ADHD.
Children with ADHD and anxiety are less hyperactive and impulsive than
children with ADHD only. On the other hand, children with AHDD plus anxiety
have more difficulty with difficult work and get "bogged down" more
frequently. Children with ADHD plus anxiety do not respond to the stimulant
medications as well. While over 80 % of children with ADHD alone will
respond to these drugs, only 30% of children with ADHD plus anxiety will
respond to the stimulant drugs. (8)
Depression
Varying degrees of depression are present in many children with ADHD,
especially after about age 10. This changes the treatment and predicts a
worse outcome. About 40% of children with ADHD have marked depression. Often
a child with ADHD will have relatives with depression. In some families,
some relatives will have ADHD and others depression. Children with ADHD and
depression are not more likely to commit suicide. (8)
Learning Disabilities
Many children with these have ADHD, it makes life even more frustrating and
difficult. About one third of ADHD children have learning disabilities.
Children with ADHD without hyperactivity have more learning disabilities
than children with ADHD. If a child with just learning disabilities is given
stimulant medication for ADHD, it will not improve their learning. However,
if a child with ADHD and learning disabilities (especially a reading
problem) is given stimulant medication, their reading improves markedly. (8)
Mania
Mania is quite rare in children, it is the opposite of depression. About 80%
of manic children have ADHD. This is a very, very severe problem when it
occurs.
Autism and related disorders
ADHD is present in about a quarter of this group, about five times what you
would expect.
Enuresis and Encopresis
Not being in control of your feces or urine is much more common in ADHD than
in children without ADHD. Having ADHD can make it harder to control these
problems. On the other hand, many times the treatment of ADHD will improve
these problems also. About 30% of children with ADHD have enuresis.
Developmental Coordination Disorder
Being exceptionally clumsy and poorly coordinated is much more common in
ADHD children. This combination can lead to very poor self-esteem,
especially in boys.
Speech-Language Disorder
This is one of the most well documented connections. ADHD is much more
common in this group. ADHD can make speech therapy much more difficult.
Epilepsy
About 20-30% of children with epilepsy also have Attention Deficit
Hyperactivity Disorder. In a recent study, 70% responded positively to
medications for Attention Deficit Hyperactivity Disorder. (11) The
medications for Attention Deficit Hyperactivity Disorder are safe with most
siezure medications.
Auditory Processing disorder
These persons hear all right, but they have a hard time filtering out sounds
which are not important. About 50% also have ADHD or one of the sub-types of
ADHD.
Substance abuse
If you go to drug and alcohol programs for teenagers, you will find many
more cases of ADHD than you would expect. However, the good news is that
this is not due to ADHD, but due to Conduct Disorders. That is, ADHD alone
is not associated with an increased risk of substance abuse, outside of
cigarettes. Conduct disorder is associated with a marked increase in
substance abuse. So if your child has conduct disorder and ADHD, there is a
great risk of substance abuse. But if the child just has ADHD, he or she is
not at a higher risk for drug abuse as a teenager. (22)
There is some evidence to suggest that if a person still has ADHD as an
adult, even without conduct disorder, they will be at a greater risk for
alcoholism. (23)
Comorbidity doesn't always mean just two disorders. I frequently see two or
three different disorders besides ADHD in one child.
