At the same time Lindemann was laying the foundation for the study of grief and dysfunctional grieving, Alexandra Adler conducted psychiatric observations and questionnaires over eleven months with more than 500 survivors of the fire, publishing some of the earliest research on post-traumatic stress disorder. More than half of the survivors exhibited symptoms of general nervousness and anxiety which lasted at least three months. Survivors who lost consciousness for a short period of time during the incident exhibited the most post-traumatic mental complications. Adler noted that 54% of survivors treated at BCH and 44% of those at MGH exhibited "post-traumatic neuroses", and that a majority of the survivors' friends and family members showed signs of "emotional upset that attained proportions of a major psychiatric condition and needed trained intervention." Adler also discovered one survivor with a lasting brain lesion who presented symptoms of visual agnosia, most likely caused by exposure to carbon monoxide fumes, other noxious gases and/or a lack of sufficient oxygen.