My first experience of the semantic headaches self-deception creates when working in a literary genre (creative non-fiction) that aims to capture the nuance and subtlety of life – the real “truth,” as it were – happened in 2005. It was Toronto’s “summer of the gun,” and my assignment was to interview victims of gun violence and write about what it’s like to be shot.

A simple assignment, but in the reporting, I realized writing about trauma poses unique challenges for the journalist. When an event is outsized and beyond our normal coping skills, the mind can construct barriers to self-knowledge, and since these usually impede any real understanding of the events one is desperately trying to process, it leaves one wondering who has built them and why. When something bad happens, we often do strange things, and don’t always know the reason why we behave the way we do.

All this I knew on an intellectual level. And yet when it came to my own story, I found I was unable to apply this professional understanding to my personal life.

The difficulties began when I started writing Invisible North, my memoir of four months spent living in Kashechewan, a troubled northern Ontario reserve. While there, I witnessed first-hand the intergenerational impact of the legacy of residential schools. Children with records of suicide attempts slashed into their arms or the yellow craters of cigarette burns where they had tried to numb the emotional pain. There were nine cases of arson that year, yet there was no fire department. Kids came to my door hungry. My heartbreak at the situation calcified to anger, and I began to drink heavily to manage my emotions. On returning home, my family doctor diagnosed me with post-traumatic stress disorder.

When I began to conceive of the book, it was apparent to everyone involved – including my agents and publisher – that my condition would have to play an important role. That an outsider could mentally and physically break down after just four months spoke volumes about the conditions of some of our reserves.

PTSD is notoriously difficult to write about. Its definition, according to the Diagnostic and Statistical Manual of Mental Disorders, changed greatly between my being diagnosed and writing the book, and debate continues to rage over all aspects of treatment and nosology, including whether it is a disorder or an injury, how intense the symptoms must be, and what are legitimate causes. In the absence of clarity, various experts have weighed in with their own explanations.

Broadly, these theories fall into two categories. The first, popularized by experts such as West Point psychology professor Lt. Col. Dave Grossman, analyzes what has happened to the patient, and the severity of the trauma experienced or witnessed. Under this definition, the likelihood of PTSD multiplies with the intensity of fear, pain, and injury; for example, being raped is more likely to cause symptoms than inappropriate sexual touching.

The second theory is action-driven, meaning it focuses on what the subject has done. In this conception, popularized by the work of specialists like retired Navy psychiatrist William Nash and clinical psychologist Brett T. Litz, PTSD isn’t simply a consequence of something external that has been witnessed or experienced. Instead, it results from the way one behaves in response to the trauma, with specific reference to whether one acts in accordance with one’s own moral values, or, by contrast, does something perceived to be embarrassing or shameful. Veterans looking back on their time in Iraq or Afghanistan are prone to wonder, “In my little sphere of influence, how well did I or didn’t I live up to the ideals?” explains Nash, who, as a combat therapist, deployed with marines to Iraq. Often, he said, the soldiers’ inability to answer that question in a satisfactory way “is what kills them.”

Early drafts of my book stuck to the former definition, explaining the condition through the shock of my first-hand experience. Resources for the residential schools’ legacy had been promised with Stephen Harper’s 2008 apology. Yet, in Kashechewan, there are none. Without help, crisis had become normalized.

When the editing process for the manuscript got underway, my brilliant editor, Michael Melgaard, began to ask difficult questions. What exactly had caused my mental break? Simply the act of witnessing? And if so, why did I feel a sense of overwhelming guilt? As he probed further, we both realized something important was missing from the book. Returning to a diary I kept while living in Kashechewan changed the book’s focus. There, in vivid detail, was a description of the events that led to my mental descent. I don’t have the space to explain fully what happened and why, except to write that I definitely did not live up to my own ideals. Instead, I ended up lashing out at the Kashechewan children whom I had been trying to help. In my shame, I dismissed those events in my own mind, then forgot about them altogether.

How we relate to difficult truths became one of the volume’s central themes. As I delved deep into indigenous history, poring over historical archives and Access to Information requests, I wondered whether my own personal story was a metaphor for a larger problem, and whether we as a society have banished from the historical record those elements of our collective experience that are uncomfortable and embarrassing. Many of the human-rights abuses against First Nations have been glossed over, or written about in terms that appear to lessen the wrongdoing and sanitize their emotional impact. Were we as a nation guilty of the same sin that had plagued me in the writing of this book?

Alexandra Shimo’s Invisible North: The Search for Answers on a Troubled Reserve will be published by Dundurn in August.

Update, July 4, 2016: In the print version of this essay, Alexandra Shimo’s upcoming book was mentioned by an earlier title. This online version has been updated to reflect the the change to Invisible North.