Co-morbid PTSD and suicidality in individuals with schizophrenia and substance and alcohol abuse

Suicide risk is high in schizophrenic patients and is further elevated in dual diagnosis patients. Suicide behaviour is a continuum from ideation, plans to attempts. Exposure to traumatic stress and co-morbid PTSD is elevated in schizophrenic patients. Suicide behaviour is also common in non-psychotic PTSD patients. This study aimed to investigate the effect of trauma and co-morbid PTSD on suicide behaviour in dual diagnosis patients and whether co-morbid PTSD would further elevate suicide risk.

This was a cross-sectional study in which suicide behaviour was compared in those with and without co-morbid PTSD in 110 patients suffering schizophrenia and alcohol and/or substance abuse.

100 (91%) reported at least one traumatic event with an average of 4.3 events. 31 (28%) patients met criteria for full PTSD. Current suicidal ideation was reported by 39 (35%) and 23 (21%) reported plans and ideation, 69 (63%) reported at least one previous suicide attempt. Suicide behaviour was significantly associated with an increasing number of traumatic events. Suicidality was significantly associated and elevated with co-morbid PTSD. Analysis indicated that the effect of trauma on suicide behaviour appeared to be mediated by hopelessness.

Suicide behaviour was not associated with exposure to trauma per se but was associated with incremental exposure to traumatic experiences. Consistent with the study hypotheses, co-morbid PTSD further adds to the risk of suicide behaviour in an already vulnerable group.