Page 471 - Total War on PTSD

It is important to understand that each person has different acceptance and tolerance levels to changes in their environments based on experiences, temperaments, perceptions, motivations and organizational skills. How much change is required to push a person over the edge varies with that individual’s “How am I” and “Who am I” pathways, which alters electrical and chemical signals in the retina. As we have established, these pathways are often damaged in those suffering from PTSD. Because sensory systems interact; each person has an optimal load and an upper threshold of tolerance before a breakdown occurs. In patients with PTSD, this threshold is far lower than it is for the general population. Most individuals have large ranges of comfort and tolerance and can readily adapt to change. However, such adaptation is oftentimes difficult for people who have sustained brain injuries or experienced shocking circumstances. Their protective mechanisms take over and hinder cognitive processing. The nervous system becomes hyper-sensitized.
External environmental signals affect a person’s internal systems. Similarly, internal signals can influence the filtering abilities of external sensory systems. For example, exposure to noise impacts retinal sensitivity. Running with a peaceful water scene in the background elicits different stress chemicals than running while being chased by wild dogs. Sudden, unexpected movement caught out of the corner of one’s eye can cause internal chemical and muscular systems to react. These internal systems, which are beyond conscious control, are triggered simply by a moving shadow on the peripheral retina. When we consider PTSD in this light, we can begin to see the solutions.
Humans have built-in protective mechanisms, and these mechanisms are stronger in patients with PTSD. When they pass their individualized comfort range and go into a
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