The British Journal of Psychiatry (2004) 185: 95-96


There is only one functional somatic syndrome*

Simon Wessely
Department of Psychological Medicine, GKT School of Medicine, 103 Denmark
Hill, London SE5 8AF,UK. E-mail:

Peter D. White
Department of Psychological Medicine, St Bartholomew's Hospital, London
EC1A 7BE,UK. E-mail:

Edited and introduced by Mary Cannon, Kwame McKenzie and Andrew Sims

* This proposition was debated on 1 October 2003 at St Bartholomew's
Hospital, as part of East London and the City Mental Health NHS Trust's
monthly multidisciplinary academic afternoon, with Professor Stephen
Stansfeld in the chair.

Functional somatic symptoms and syndromes are a major health issue. They
are common, costly, persistent and may be disabling. Most of the current
literature pertains to specific syndromes defined by medical
subspecialties. Indeed, each medical subspecialty seems to have at least
one somatic syndrome. These include: irritable bowel syndrome
(gastroenterology); chronic pelvic pain (gynaecology); fibromyalgia
(rheumatology); non-cardiac chest pain (cardiology); tension headache
(neurology); hyperventilation syndrome (respiratory medicine) and chronic
fatigue syndrome (infectious disease). In 1999, Wessely and colleagues
concluded on the basis of a literature review that there was substantial
overlap between these conditions and challenged the acceptance of
distinct syndromes as defined in the medical literature (Wessely et al,
1999). They proposed the concept of a general functional somatic
syndrome. But is there any empirical evidence for such a general
syndrome? Is it even a useful concept? Five years on, Professor Simon
Wessely, King's College London, revisits this debate. He is opposed by Dr
Peter White from St Bartholomew's Hospital and Queen Mary School of
Medicine and Dentistry, London.

When Mike Sharpe, Tok Nimnuan and I proposed in the Lancet (Wessely et
al, 1999) that the classification of the world of unexplained syndromes
was a mess, we had little idea of how controversial it would prove to be.
This debate is, therefore, a welcome opportunity to make it clear what we
did, and did not, say.

Our starting point was that every medical specialty has its own
'unexplained' syndrome, by which we mean a diagnostic label used in that
clinic to describe patients with symptoms, disability, but no clear-cut
biomedical mechanism to explain their distress. Gastroenterologists see
people with irritable bowel syndrome, rheumatologists see fibromyalgia,
infectious disease specialists frequently diagnose post-viral fatigue
syndrome, and so on and so forth.

However, as time passed, more and more reports described the overlaps
between two or more of these syndromes. If one studied a population with
the label of fibromyalgia, many also fulfilled criteria for chronic
fatigue syndrome. Patients presenting with irritable bowel syndrome have
high rates of tension headaches. Women with chronic pelvic pain also had
marked myalgic symptoms. And again, so on and so forth. Indeed, the
literature on these syndromes showed numerous similarities. The
epidemiology seemed similar. Putative mechanisms overlapped
(abnormalities of serotonin function, for example, have been found in
many of these syndromes). Outcomes seemed similar, and not encouraging.
All had links to depression and anxiety. And there was considerable
overlap in successful treatment strategies, especially those involving
some variety of active rehabilitation, such as cognitive-behavioural
therapy (CBT).

So why did our article provoke so much reaction? (Although, to be fair,
this was rarely among professionals, most of whom had no problem in
accepting our thesis, particularly if they belonged to that disappearing
breed, the general physician.) There were two reasons. First, many
sufferers did not accept the thesis, and continue to have strong
emotional attachments to their label. A person who believed powerfully
that they were a victim of multiple chemical sensitivity, for example,
did not always take kindly to the view that they also had links to
atypical chest pain or irritable bowel syndrome, even if they had the
symptoms of both. Explanations advanced for these syndromes clearly
differ - a patient attending a gynaecology clinic with pre-menstrual
syndrome has a very different idea of why they are sick than a person
attending a clinic for chronic fatigue syndrome. Nevertheless, our
argument that the symptoms overlap to a very great extent is not
disproved by this, even if the explanations advanced by patient or
professional differ.

Second, some felt that what we were saying was that all these syndromes
are psychiatric. Those offended by this idea were often those who also
equated the word psychiatric with imaginary or non-existent, a
regrettable view sadly made more regrettable because it is also held by
some professionals. But this has never been our argument. What we said is
that all of these syndromes still fall under the title of 'unexplained'
since no consensual scientific explanation has been advanced for any of
them that meets with universal acceptance. Unexplained means what it says
on the tin, and is not a code for psychiatric, still less for 'all in the

Five years later, Sharpe and I stand by our thesis. We are not saying
that all these syndromes are the same. We do believe that in time
differences will emerge that will enable us to divide up the unexplained
cake better than at present. We believe that better understanding and
classification will result from an improved understanding of mechanisms.
Conversely, we do not expect that improved understanding will come from
further statistical manipulations of symptoms and their occurrence. The
symptom-based classifications that we have now are more a reflection of
professional specialisation and access to care, and do not cleave nature
at the joints.

Wessely and colleagues (1999) have suggested that patients with diverse
medically unexplained symptoms 'may have... a general functional somatic
syndrome'. Telling patients that they have a psychosomatic disorder is
usually the first step in a deteriorating doctor-patient relationship. To
most lay people, psychosomatic means malingering or 'all in the mind'.
Lumping functional somatic syndromes together as a general functional
somatic syndrome conceptually supports mind/body dualism, feeding this
misapprehension. A general functional somatic syndrome can be consistent
only with psychogenesis, since it is difficult to conceive of a
pathophysiological mechanism that would be common to all functional
somatic syndromes. The alternative of deconstructing or splitting
functional somatic syndromes into their constituent parts leads both to a
more sophisticated understanding of these illnesses and to better
treatments, using the biopsychosocial approach.

Wessely and colleagues suggest that case definitions of functional
somatic syndromes overlap. However, there is little overlap in the core
symptoms of the two most common syndromes: irritable bowel syndrome and
fibromyalgia. The apparent overlap is also confounded by both co-morbid
mood disorders and selection bias. Primary care and community studies
find lower rates of overlap of functional somatic syndromes than do
secondary care studies (Jason et al, 2001; Whitehead et al, 2002).

Most doctors are either 'splitters' or 'lumpers' as they classify
ill-health. Historically, more progress has been made through splitting
illnesses rather than lumping them together. Take the example of dropsy
(generalised oedema), which was thought to be a single disease, until it
was divided into heart, kidney and liver causes. Psychiatric taxonomies
are similarly misleading and dualistic. A somatoform disorder can only be
so classified in the absence of an adequate physical explanation (World
Health Organization, 1992). Furthermore, a somatoform pain disorder can
only '... occur in association with emotional conflict or psychosocial
problems that are sufficient to allow the conclusion that they are the
main causal influences' (World Health Organization, 1992). How can the
clinician be sure that the psychosocial problem actually caused the
illness? Somatisation is generally more useful when regarded as a process
that is essentially independent of diagnosis, and which can therefore be
applied to a patient with any medical condition.

The concept of a general functional somatic syndrome does not lead to
better understanding of aetiology. For instance, there is a five-fold
risk of chronic fatigue syndrome in patients suffering from infectious
mononucleosis (White et al, 1998), whereas there is no evidence that
fibromyalgia is caused by infections (Rea et al, 1999). Lumping
fibromyalgia and chronic fatigue syndrome together as a general
functional somatic syndrome would have reduced the chance of finding this
effect (because of dilution). Moreover, the risk factor of childhood
sexual abuse varies six-fold across different functional somatic
syndromes (Romans et al, 2002). It is only by separating general
functional somatic syndrome into its separate disorders that we will
advance understanding of causation. We have started to understand the
pathophysiology of fibromyalgia as central nervous system
supersensitivity due to brain neuroplasticity (Gracely et al, 2002). We
have gone further by starting to deconstruct individual functional
somatic syndromes, such as chronic fatigue syndrome, into aetiologically
different disorders.

The concept of a general functional somatic syndrome does not lead to
better treatments. Antidepressant efficacy ranges widely in different
functional somatic syndromes, and may be more accurately predicted by the
presence of comorbid mood disorders. A recent systematic review showed
that '... psychosocial treatments have not yet been shown to have a
lasting and clinically meaningful influence on the physical complaints of
polysymptomatic somatisers' (Allen et al, 2002). A recent large trial of
treatment of Gulf War syndrome found no significant differences between
CBT and control treatments (Donta et al, 2003). An accompanying editorial
by Hotopf (2003) correctly attributed this lack of efficacy of CBT to not
using an illness-specific model for CBT. In contrast, CBT is effective
when specifically designed to help improve the physical functioning of
patients with chronic fatigue (Whiting et al, 2001).

Finally, the concept of a general functional somatic syndrome does not
predict prognosis, which varies by specific functional somatic syndrome.
Fibromyalgia runs a persistent and chronic course, whereas irritable
bowel syndrome runs an intermittent course with recovery being more
common. The concept of a general functional somatic syndrome, therefore,
reduces the accuracy of prognosis.

I conclude that the concept of a general functional somatic syndrome is
unhelpful in understanding illness, aetiology, treatment and outcome,
thus failing four of Kendell's tests of clinical validity (Kendell,
1989). Illnesses with unexplained physical symptoms are best considered
in an integrated way, paying equal attention to body, mind and social

Allen, L. A., Escobar, J. I., Lehrer, P. M., et al (2002) Psychosocial
treatments for multiple unexplained physical symptoms: a review of the
literature. Psychosomatic Medicine, 64, 939 -950.

Donta, S. T., Clauw, D. J., Engel, C. C., et al (2003) Cognitive
behaviour therapy and aerobic exercise for Gulf War veterans' illnesses:
a randomised controlled trial. Journal of the American Medical
Association, 289, 1396 -1404.

Gracely, R. H., Petzke, F., Wolf, J. M., et al (2002) Functional magnetic
resonance imaging evidence of augmented pain processing in fibromyalgia.
Arthritis and Rheumatism, 46, 1333 -1343.

Hotopf, M. (2003) Treating Gulf War veterans' illnesses - are more
focused studies needed? JAMA, 289, 1436 -1437.

Jason, L. A., Taylor, R. R., Kennedy, C. L., et al (2001) Chronic fatigue
syndrome: comorbidity with fibromyalgia and psychiatric illness. Medicine
and Psychiatry, 4, 29 -34.

Kendell, R. E. (1989) Clinical validity. Psychological Medicine, 19,

Rea,T., Russo, J., Katon, W., et al (1999) A prospective study of tender
points and fibromyalgia during and after an acute viral infection.
Archives of Internal Medicine, 159, 865 -870.

Romans, S., Belaise, C., Martin, J., et al (2002) Childhood abuse and
later medical disorders in women: an epidemiological study. Psychotherapy
and Psychosomatics, 71, 141 -150.

Wessely, S., Nimnuan, C. & Sharpe, M. (1999) Functional somatic
syndromes: one or many? Lancet, 354, 936 -939.

White, P. D., Thomas, J. M., Amess, J., et al (1998) Incidence, risk and
prognosis of acute and chronic fatigue syndromes and psychiatric
disorders after glandular fever. British Journal of Psychiatry, 173, 475

Whitehead,W. E., Palsson, O. & Jones, K. R. (2002) Systematic review of
the comorbidity of irritable bowel syndrome with other disorders: what
are the causes and implications? Gastroenterology, 122, 1140 -1156.

Whiting, P., Bagnall, A. M., Sowden, A. J., et al (2001) Interventions
for the treatment and management of chronic fatigue syndrome: a
systematic review. JAMA, 287, 1360 -1368.

World Health Organization (1992) The ICD-10 Classification of Mental and
Behavioural Disorders, Clinical Descriptions and Diagnostic Guidelines.
Geneva: WHO.

© 2004 The Royal College of Psychiatrists