Biological Theories of Panic Disorder

What Does Research Show About the Biological Causes of Panic Disorder?

Biological causes of panic disorder. Getty Images Credit: PeopleImages

Currently, the exact cause of panic disorder remains unknown. However, there are several theories that take different factors into account when examining the potential causes of panic disorder. Read ahead to learn more about the biological theory of panic disorder. 

The Biological Theory of Panic Disorder

Serotonin, norepinephrine and dopamine are chemicals that act as neurotransmitters or messengers in the brain.

They send messages between different areas of the brain and are thought to influence one’s mood and anxiety level. One theory of panic disorder is that symptoms are caused by an imbalance of one or more of these chemicals. 

Known as the biological theory of panic disorder, this theory examines the biological factors as the cause of mental health concerns. Support for this theory is the reduction of panic symptoms many patients experience when antidepressants, which alter brain chemicals, are introduced. Some examples are:

  1. Selective serotonin reuptake inhibitors (SSRIs) (such as Paxil (paroxetine), Prozac (fluoxetine), and Zoloft (sertraline)) work by increasing the level of serotonin in the brain.
  2. Serotonin-norepinephrine reuptake inhibitors (SNRIs) (such as Effexor (venlafaxine) and Cymbalta (duloxetine)) work on both serotonin and norepinephrine.
  3. Tricyclic antidepressants (TCAs) (such as Anafranil (clomipramine) and Elavil (amitriptyline)) affect serotonin, norepinephrine and to a lesser extent, dopamine.
  1. Monoamine oxidase inhibitors (MAOIs) (such as Nardil, Parnate) also inhibit panic by altering brain chemicals.

Additional Support for the Biological Theory 

In addition to the response of panic disorder to biochemical changes introduced by antidepressants, there is further evidence that an underlying biochemical change in the brain may lead to panic disorder including GABA and metabolic theories.

Gamma-Aminobutyric Acid (GABA)

It is believed that gamma-aminobutyric acid—GABA—is a chemical in the brain that modulates anxiety. GABA counteracts excitement in the brain by inducing relaxation and suppressing anxiety. Research has indicated that GABA may play a role in many mental health issues including anxiety and mood disorders.

Anti-anxiety medications (benzodiazepines) such as Xanax (alprazolam), Ativan (lorazepam), or Klonopin (clonazepam), work because they target GABA receptors in the brain. These medications enhance the function of GABA resulting in a calm and relaxed state.

In several studies, GABA levels in individuals with panic disorder were lower than in control subjects with no history of panic. Future research to yield a better understanding of the role of GABA in mental health disturbances will, likely, lead to improved medication options for sufferers.

Metabolic Theories and Panic Disorder

Metabolic studies focus on how the human body processes particular substances. Many of these studies have shown that people with panic disorder are more sensitive to certain substances than are their non-panic counterparts. Such observations further support the biological theory, demonstrating how those with panic disorder may have a different makeup than those without this condition.

For example, panic attacks can be triggered in people with panic disorder by giving them injections of lactic acid, a substance naturally produced by the body during muscular activity. Other studies have shown breathing air with elevated carbon dioxide can trigger panic attacks in those with the disorder. Caffeine, nicotine and alcohol have also been implicated as triggers for those with panic disorder.

What Does This All Mean?

Despite the implications of the research to date, no definitive laboratory findings can assist in the diagnosis panic disorder. Chemical messengers in the brain and metabolic processes are complex and interactive.

It may be that each of these theories has a specific importance in the development of panic disorder. Future research is needed to further delineate and tie together the biological causes of panic disorder.

Many experts currently agree that panic disorder is caused by a combination of factors. Research has also supported theories that take several factors into account such as the person's genetic and environmental influences. Researchers continue to look for the causes of mental health conditions, like panic disorder, as this can help in diagnosis and determining the best treatment options. 

While learning how biochemical processes may lead to panic disorder isn't terribly helpful in making the diagnosis of panic disorder, this knowledge may be especially helpful for those who are reluctant to take a medication to improve their symptoms. This is true for many other mental health conditions as well. There has been a stigma about mental illness, with attitudes still circulating that a person should be able to overcome a condition such as panic disorder on their own. Looking at what we are learning about the biochemical and metabolic theories of panic disorder, this thought pattern is akin to saying that someone should get over their appendicitis by having a positive attitude alone.

Sources:

Goossens, L., Leibold, N., Peeters, R. et al. Brainstem Response to Hypercapnia: A Symptom Provocation Study into the Pathophysiology of Panic Disorder. Journal of Psychopharmacology. 2014. 28(5):449-56.

Schur, R., Draisma, L., Wijnen, J. et al. Brain GABA Levels Across Psychiatric Disorders: A Systematic Literature Review and Meta-Analysis of (1) H-MRS Studies. Human Brain Mapping. 2016. 37(9):3337-52.

Zangrossi, H., and F. Graeff. Serotonin in Anxiety and Panic: Contributions of the Elevated T-Maze. Neuroscience and Biobehavioral Reviews. 2014. 46 Pt 3:397-406.

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