Many years ago Robert Sapolsky wrote a book entitled: “Why Zebras Don’t Get Ulcers”. The basic idea of the book was that acute stressors (e.g., a lion attacking a zebra) alter body physiology in adaptive ways (i.e., a fight or flight reaction) thus allowing the animal to surmount the difficulties of that particular moment. However, when the stressors become chronic what used to be adaptive responses become injurious to the body (e.g., increased heart rate may strain the cardiac muscles).
I remember during my surgical rotation receiving a bed-ridden patient who had been on anticoagulants. Because of lack of mobility she had developed pressure ulcers all over her back and my job was to take care of her wounds. Her skin had slough off and the wounds reached into her muscles. It was clear that she was in constant pain. Her ulcers were chronic stressors and she could not escape them.
Chronic stressors in today’s society are usually different from those of my patient with pressure ulcers. Contrary to stress in other species, chronic stressors in humans are not the result external factors; more often than not they are self-generated. Our chronic stressors tend to be psychological, such as worrying about things we can’t change. They also come and go in waves, with the recovery phase after each relapse taking longer and longer to correct itself.
Temple Grandin often calls attention in her books to the debilitating aspects of anxiety. According to a recent study approximately 40% of autistic individuals exhibit an anxiety disorder roughly divided among the following (van Steensel et al., 2011):
Specific phobias 30%
Obsessive compulsive disorder 17%
Social anxiety Disorder 15%
Separation Anxiety Disorder 9%
Panic Disorder 2%
I have often wondered how many of the manifestations usually attributed to the core pathology of autism are really the effect, or an exacerbated side effect of, chronic stress. Some people believe, for example, that the social phobia exhibited by some autistic individuals is a post-traumatic stress disorder (PTSD). In this scenario autistic individuals who fail in their first attempts at social intercourse are forced to relieve their painful experience on subsequent attempts. Under these circumstances self-consciousness builds into fear. The end result would be for some autistic individuals to shy away from further social contact.
Chronic stress offers a gender bias and may be more prominent in females. In females chronic stress has the added confound of lowering estrogen levels and playing havoc with the menstrual cycle. Chronic stress also lowers the immune defenses of your body making you more prone to infectious conditions. It also increases the risk for flare-ups of autoimmune conditions. Several studies have linked an increased prevalence of autoimmune conditions to autistic individuals and their relatives. Indeed, arthritis of the spine may be more common in autism just as mothers with rheumatoid arthritis are more likely to give birth to an autistic individual.
Animal studies reveal that chronic stress diminishes brain dopamine levels. It seems that the anticipation of pleasure provided by this neurotransmitter is diminished under chronic stress. The end result may be a mixed mood state of anxiety-depression. Some of the clinical manifestations that may offer warning signals as to the presence of chronic stress are: memory problems, poor judgment, constant worrying, isolating yourself from others, nervous habits, frequent colds, irritability/short temper, and changes in sleeping habits. Autistic individuals suffering from these symptoms may be in need of medical intervention.(Note: As an interesting side note glugocorticoids that are released during stress have a high density of receptors in both the frontal cortex and hippocampus. Damage to these areas of the brain may explain many of the previously mentioned symptoms).
Lastly, chronic stress worsens clinical outcomes in neurological disorders. This may be quite evident in autistic individuals who suffer from seizures as they are often unresponsive to medications. Although I have not found any appropriate literature, we could also speculate as to a poorer outcome to stroke.
A useful link that discusses the role of cognitive behavioral therapy as treatment for anxiety disorders in autism and the role of the parents in treating anxiety can be found at: http://www.iidc.indiana.edu/?pageId=3616
Van Steensel FJA, Bogels SM, Perrin S. Anxiety disorders in children and adolescents with autistic spectrum disorders: a meta-analysis. Clinical Child and Family Psychology Review 14:302-317, 2011.