What are some of the causes of panic disorder?
Panic disorder can run in families. One study showed that if one twin in a genetically identical pair has panic
disorder, it is likely that the other twin will also. Fraternal,
or non-identical twin pairs do not show this high degree of
“concordance” with respect to panic disorder. Thus, it appears
that some genetic factor, in combination with environment, may be
responsible for vulnerability to this condition.
Scientists have studies families in which several
members have panic disorder. The aim of these studies is to
identify the specific gene or genes involved in the condition.
Identification of these genes may lead to new approaches for
diagnosing and treating panic disorder.
Brain and Biochemical Abnormalities
One line of evidence
suggests that panic disorder may be associated with increased
activity in the hippocampus and locus coeruleus, portions of the
brain that monitor external and internal stimuli and control the
brain’s responses to them. Also, it has been shown that panic
disorder patients have increased activity in a portion of the
nervous system called the adrenergic system, which regulates such
physiological functions as heart rate and body temperature.
However, it is not clear whether these increases reflect the
anxiety symptoms or whether they cause them.
Another group of studies suggests that people with panic disorder
may have abnormalities in their benzodiazepine receptors, brain
components that react with anxiety-reducing substances within the
In conducting their research, scientists can use several
different techniques to provoke panic attacks in people who have
panic disorder. The best known method is intravenous
administration of sodium lactate, the same chemical that normally
builds up in the muscles during heavy exercise. Other
substances that can trigger panic attacks in susceptible people
include caffeine (generally 5 or more cups of coffee are
required). Hyperventilation and breathing air with a
higher-than-usual level of carbon dioxide can also trigger panic
attacks in people with panic disorder.
Because these provocations generally do not trigger panic
attacks in people who do not have panic disorder,
scientists have inferred that individuals who have panic disorder
are biologically different in some way from people who do not.
However, it is also true that when the people prone to panic
attacks are told in advance about the sensations these
provocations will cause, they are much less likely to panic.
This suggests that there is a strong psychological component, as
well as a biological one, to panic disorder.
NIMH-supported investigators are examining specific parts of the
brain and central nervous system to learn which ones play a role
in panic disorder, and how they may interact to give rise to this
condition. Other studies funded by the Institute are under way
to determine what happens during “provoked” panic attacks, and to
investigate the role of breathing irregularities in anxiety and
Scientists funded by NIMH are
investigating the basic thought processes and emotions that come
into play during a panic attack and those that contribute to the
development and persistence of agoraphobia. The Institute also
supports research evaluating the impact of various versions of
cognitive-behavioral therapy to determine which variants of the
procedure are effective for which people. The NIMH panic
disorder research program will also explore the effects of
interpersonal stress such as marital conflict on panic disorder
with agoraphobia and determine if including spouses in the
cognitive-behavioral treatment of the condition improves outcome.