Australian researchers say PTSD treatments need to change from solely psychological assistance to include a variety of physical symptoms as well.

The mind and body are intimately linked, which is why there needs to be a change in the way post-traumatic stress disorder (PTSD) is treated, say Australian researchers.

A study of Australian Vietnam War veterans, published in the Medical Journal of Australia, has shown PTSD is not purely psychological. It impacts the gastrointestinal, cardiovascular and respiratory systems too.

PTSD is also associated with sleep disturbances.

Professor Alexander McFarlane, director of the Centre for Traumatic Stress Studies at the University of Adelaide, says the "failure" to treat the "biological" symptoms of PTSD has not served patients well.

"The limited effectiveness of evidence-based psychological interventions in people with PTSD, particularly in veteran populations, highlights the need to develop biological therapies that address the underlying neurophysiological and immune dysregulation associated with PTSD," Prof McFarlane wrote in an editorial for the MJA.

Prof McFarlane says PTSD should be viewed as a systemic disorder with comorbidities, or co-occurring physical conditions or diseases.

Researchers from the Gallipoli Medical Research Institute (GMRI), the University of Queensland, the Queensland University of Technology Institute of Health and Biomedical Innovation, and Greenslopes Private Hospital in Brisbane, analysed the health of nearly 300 Vietnam War veterans between 2014-15.

Of these, 108 were confirmed as having had PTSD, and 106 served as trauma-exposed control participants who did not have PTSD.

The average total of comorbidities was higher among those with PTSD (17.7 per cent) than in trauma-exposed controls (14.1 per cent), according to the research.

"For 24 of 171 assessed clinical outcomes, morbidity was greater in the PTSD group, including for conditions of the gastrointestinal, hepatic, cardiovascular, and respiratory systems, sleep disorders, and laboratory pathology measures," the authors wrote.