Dr Hickie discussed in detail reasons why he thinks Chronic Fatigue Syndrome is not caused by depression or other psychological factors. He also emphasised the influence the work of the Sydney research team is having internationally on the understanding of CFS.

Over 80% of CFS patients in the first gammaglobulin trial reported neuropsychological or psychological complaints as their primary complaints. "With regards to neuropsychological complaints, their primary symptoms are concentration and memory impairment; and with regards to psychological complaints, principally depression, irritability and lability - that is, their rapidly changing moods, of being happy one minute and being tearful the next, and of some anxiety and worry....So no matter what particular bias one has, with regards to the evaluation of Chronic Fatigue, one has to come up with some explanation for this degree of psychological symptomatology that patients are complaining of."

"Now basically, there have been three styles of hypotheses put up to attempt to explain the psychological symptoms. The first, not always just put by psychiatrists, but by other physicians, is that Chronic Fatigue Syndrome is some form of primary psychiatric disorder. The second hypothesis is that Chronic Fatigue occurs in psychologically vulnerable individuals; that there is some psychological factor that makes those people vulnerable to Chronic Fatigue. The third, the immunological hypothesis that Professor Dwyer presented earlier on and characteristic of our group, is that both psychological and physical symptoms arise basically from the same medical pathology, that there is some pathological process going on within the central nervous system that is producing both physical and psychological complaints. Now, as a psychiatrist, I want to deal primarily with the first two of these hypotheses."

"The first and most important, and probably the most widely discussed around the world, is that Chronic Fatigue is basically an unrecognised form of depression. That if such patients were seen by a psychiatrist they would be recognised as having a major depressive illness. Now, although we have argued against this particular point of view, it does have a great deal of currency, and Professor Kendall, who is one of the leading psychiatrists in the United Kingdom, recently had a review article published in 'The Lancet' basically arguing this point of view. A summary of his argument goes as follows: fatigue is a very common complaint and fatigue itself is one of the hallmarks of a depressive illness. Both fatigue and depressive symptoms are common in the general community, and one would expect to see both depression and fatigue commonly. On an epidemiological basis, itís well known that depression has its highest prevalence in women between the ages of 20-40, and from the reported studies around the world you would think that this is the group principally affected by Chronic Fatigue Syndrome."

Professor Kendall also said that people with CFS have a high rate of diagnosed major depression as determined in formal psychiatric interviews; that as far as he was aware, neither CFS nor depression is common in children; and that depression may account for any reported immune abnormalities in CFS.

"His basic argument would be that the only basic difference between Chronic Fatigue and depression is one of attribution, that is, that depressives blame themselves for their illness whereas those with Chronic Fatigue tend to blame some external factor such as a virus or a chemical or some other factor in the environment."

Dr Hickie listed ten key factors that argue against the idea that CFS is simply unrecognised depression:

Epidemiological evidence. The only work in the world which resembles a basic epidemiological study of CFS was that done by the Sydney researchers in the Lismore region of NSW. It was found that men and women suffer from CFS in approximately equal numbers. The study also found that CFS is a relatively rare disorder (37 per 100,000). Both these factors differ from findings in true depression. As well, children and adolescents represent a greater percentage of sufferers in CFS than they do in depression.

Symptom profile. The following are general characteristics of depression but not of CFS: anhedonia (lack of pleasure in life); weight loss; suicidal ideation; severe psychomotor change; pathological guilt; and severe anxiety.

Depression severity. Severity of depression in CFS is much less than that reported by patients with typical depressive illnesses.

Personality differences. CFS patients do not report neuroticism. In personality style they donít really resemble patients with depressive illnesses.

Neuroendocrine abnormalities. In neuroendocrine investigations, CFS patients tend to have opposite profiles to people with depression. CFS patients exhibit 'hypocortisolism', while those with depression exhibit 'hypercortisolism'.

Sleep disturbance. There are characteristic sleep pattern changes reported in depressed patients. Those same abnormalities are not reported in CFS.

Pre-morbid psychiatric disorder. Although a controversial area, the studies of the Sydney team indicate that before their illness, CFS patients did not suffer from depression more often than the general community. However, most depressed people have experienced depression quite often throughout their adult lives.

Response to psychological treatments. At this stage, no one has been able to demonstrate that patients with CFS respond to anti-depressant therapy in the same way that patients with depressive illnesses do.

Immunological changes in CFS. High rates of particular abnormalities have been found in CFS patients but not in depressed patients.

Response of psychological symptoms with immunological therapy. Studies have shown that if CFS patients get better physically with gammaglobulin, they also get better psychologically. The whole syndrome goes away. This suggests these two aspects are linked.

Dr Hickie doesn't believe that the hypothesis that psychologically vulnerable people get CFS stands up to study, for the reasons outlined in the points above. Vulnerability, however, can be seen in many terms: it may be genetic vulnerability, or a pre-existing medical condition that pre-disposes to CFS, not psychological vulnerability.

Dr Hickie favours the view that psychological symptoms in CFS are part of the illness itself, not just a psychological reaction to the illness:

"Those who take a much more organic, if you like, or particularly medical view of Chronic Fatigue Syndrome, still have to account for the psychological factors that people complain of....we think cytokines can account for both the physical and psychological symptoms. That is what I have labelled accounting for the symptoms in an intrinsic way, that is, when you get the illness you get the psychological symptoms. You don't simply get the psychological symptoms as a reaction to the illness, but as part of the illness itself. The alternative view for those who would argue medical models is that people get depressed after they get ill, after a long period of time. That doesn't seem to me to account for the other psychological symptoms that people get frequently. I'm more attracted to the first type of model, where it is argued that something intrinsically is happening in the central nervous system, rather than just simply being a psychological reaction to the illness."

At the meeting organised by the National Institutes of Health in the United States last year (1991), Dr Hickie said that "It was very clear that there was a large bonus from having collected a group of psychiatrists at that meeting. That is, prior to the involvement of the psychiatrists, the physicians had agreed that they would throw out anyone who had these psychological symptoms, and it was only when they got a bunch of psychiatrists involved that they said, 'That's crazy guys. Don't throw them out, because all people with medical disorders and anyone having a disease of the central nervous system is going to have those particular symptoms. You are going to throw out the people you are most interested in.' In fact, at that meeting they agreed that they would have to revise their criteria to say that both psychological and medical assessment were essential, but in no sense was that necessarily the cause of the syndrome."

"The kind of research we have been able to do in Australia has influenced a great deal of international thinking. We were actually able to present evidence with regard to psychological symptoms, with regard to epidemiology, with regard to immunology, with regard to response different treatments, none of which, to that stage, had been undertaken in the United States, and only half of which they were aware of....We have actually been able to have a major influence on thinking in this area and particularly on thinking with regard to psychological symptoms."

Reprinted from Emerge, September 1992.