People with mood disorders are more likely than the general population to have experienced at least one traumatic event in their lives (“traumatic” meaning being exposed to death or serious injury or the threat of death or serious injury to oneself or to someone close by)1. This is particularly true in those who have experienced several mood episodes, for instance, repeated episodes of depression.
For this reason we pay close attention to traumatic events when we are doing an initial consultation with a new patient. We find that many patients have symptoms of both posttraumatic stress disorder (PTSD) and depression, and the focus of treatment often shifts from mood symptoms to PTSD symptoms in the course of our work with a new patient.
PTSD symptoms overlap with mood symptoms (depression, avoidance, irritability, doubt about the future) but there are characteristic symptoms that are not found in people with simple depression — especially symptoms of “hyperarousal.” This refers to a “fight or flight” reaction that seems excessive in a given situation. For instance, feeling terrified suddenly while walking in a park in the evening2. These experiences are often triggered by events that evoke past memories. Vulnerability to hyperarousal varies depending on the level of stress a person is facing. In highly stressful circumstances a person may notice trouble sleeping, nightmares, or “panic attacks.”3 These could be due to depression, but often anxiety or irritability is more prominent than sadness.
PTSD is a condition which demonstrates that the common stereotype that psychiatric disorders can be divided into those that are due to life experiences (and therefore psychological) and those that are due to genes (and therefore biological) is false. PTSD is a profoundly biological disorder that is due to life experiences4.
Some of the biological findings in PTSD include evidence that traumatic events lead to the formation of “traumatic memories” which are memories that are like short video clips (memories with powerful images and sounds which evoke physical responses in the body that are identical to the original fear response, and which don’t fade the way typical memories fade) and which are created when fear circuits from the amygdala interact with memory circuits in the hippocampus5. There is also evidence that PTSD leads to a potentially life-long alteration in the body’s response to stress: a hyperactive fight or flight response from the sympathetic nervous system which may be due to turning off the parasympathetic nervous system, which mediates reflective and relaxed states of mind6.
Treatments for PTSD try to convert traumatic memories into more typical verbal or story memories (through the use of “exposure therapy”), or try to reduce the hyperarousal response (through the use of medications that reduce arousal, like propranolol and, indirectly, antidepressants), or try to increase the activity of the parasympathetic nervous system (through meditation, biofeedback, and other techniques)7.
1. Otto MW, Perlman CA, Wernicke R, Reese HE, Bauer MS, Pollack MH. Posttraumatic stress disorder in patients with bipolar disorder: a review of prevalence, correlates, and treatment strategies. Bipolar Disord. 2004 Dec;6(6):470-9.
2. American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC: Author.
3. Rachel Y. Post-Traumatic Stress Disorder. N Engl J Med 2002; 346:108-114 January 10, 2002
4. Cardenas VA, Samuelson K, Lenoci M, Studholme C, Neylan TC, Marmar CR, Schuff N, Weiner MW. Changes in brain anatomy during the course of posttraumatic stress disorder. Psychiatry Res. 2011 Aug 30;193(2):93-100.
5. Mahan AL, Ressler KJ. Fear conditioning, synaptic plasticity and the amygdala: implications for posttraumatic stress disorder. Trends Neurosci. 2011 Jul 26.
6. Blechert J, Michael T, Grossman P, Lajtman M, Wilhelm FH. Autonomic and respiratory characteristics of posttraumatic stress disorder and panic disorder. Psychosom Med. 2007 Dec;69(9):935-43.
7. Foa, Edna B. (Ed); Davidson, Jonathan R. T. (Ed); Frances, Allen (Ed); Culpepper, Larry (Ed); Ross, Ruth (Ed); Ross, David (Ed). The expert consensus guideline series: Treatment of posttraumatic stress disorder. Journal of Clinical Psychiatry, Vol 60(Suppl 16), 1999, 4-76.