Can Biology Explain Panic Disorder?by Jerry Kennard, Ph.D. Medical Reviewer
Most experts agree that both biological and psychological issues are involved in panic disorder. The area of debate is around the relative importance of each and how they may combine or interact. An influential proponent of the biological theory of panic is Professor Donald Klein, of the Columbia University Medical Center. It was Klein who originally suggested that people who suffer with repeated panics had a distinct disorder. Eventually his views, and the gathering weight of related research, were accepted and the diagnosis of panic disorder was incorporated into Diagnostic and Statistical Manual. Although Klein's theory is just one of several biological theories, it provides a useful platform from which to describe the strengths and limitations of the biological approach to panic.
Two particular issues helped to persuade Klein that the experience of panic was different to other forms of anxiety. First was the fact that medications prescribed for anxiety appeared to have no effect on people who experienced panic. Secondly, in laboratory experiments, many panic sufferers could be induced into having a panic attack by giving them sodium lactate. Moreover, the use of the antidepressant drug imipramine had a suppressing effect on panic. This combination of effects (one a cause, one a blocking agent) suggested to Klein that the basis of panic was biological in nature.
Klein's original model of panic suggested that sufferers have a super-sensitive alarm system that is triggered by the nervous system. He proposed that the discharges in the nervous system were linked to separation anxiety and suffocation. Spontaneous panics then make the person apprehensive about further episodes. This increases anxiety and leads the person to seek more reassurance and safety. Eventually this leads to the person becoming agoraphobic.
Subsequent research confirmed Klein's assertion that panic leads to fear which leads to avoidance. However Klein's assertion that patients with panic disorder did not respond to anti-anxiety drugs was less convincing, as many did. Moreover, the sodium lactate laboratory tests which suggested that panic disorder patients responded distinctively and predictably to the substance, were later revised. After further analysis it was established that approximately half of panic disorder patients gave a panic response when given sodium lactate. This suggested that even if the substance did trigger an over-sensitive alarm system it only applied to a sub-set of patients. An added complication arose in the fact that when the sodium lactate test was applied to people with no prior history of panic, some experienced panic.
Despite the problems, Klein's biological theory is far from being disproved. Klein later revised the theory and suggested we all have an in-built suffocation alarm system that is super-sensitive in certain people. The fact that many panic sufferers do experience breathing difficulties and fear suffocation has encouraged further research into the area. Klein's theory is only one of several biological theories that offer interesting if unsubstantiated or, as yet, unconvincing evidence.
Rachman, S., De Silva, P (2003) Panic Disorder the facts (2nd Ed) Oxford University Press