Functional disorders can affect the interplay of several organ systems (for example gastrointestinal, respiratory, musculoskeletal or neurological) leading to multiple and variable symptoms.
This difficulty in 'seeing' the processes underlying the symptoms of functional disorders has often resulted in these conditions being misunderstood and sometimes stigmatised within medicine and society.
There are many examples of symptoms that individuals may experience; some of these include persistent or recurrent pain, fatigue, weakness, shortness of breath or bowel problems.
[citation needed] Most medical specialties define their own functional somatic syndrome, and a patient may end up with several of these diagnoses without understanding how they are connected.
In clinical populations, functional disorders are common and have been found to present in around one-third of consultations in both specialist practice[5] and primary care.
When healthcare professionals are giving a diagnosis and carrying out treatment, it is important to communicate openly and honestly and not to fall into the trap of dualistic concepts – that is "either mental or physical" thinking; or attempt to "reattribute" symptoms to a predominantly psychosocial cause.
[16] Explanatory models that support our understanding of functional disorders take into account the multiple factors involved in symptom development.
A personalised, tailored approach is usually needed in order to consider the factors which relate to that individual's biomedical, psychological, social, and material environment.
[17] More recent functional neuroimaging studies have suggested malfunctioning of neural circuits involved in stress processing, emotional regulation, self-agency, interoception, and sensorimotor integration.
[23] Medical bias possibly contributes to the sex differences in diagnosis: women are more likely to be diagnosed than men with a functional disorder by doctors.
[28][29] Alexithymia (difficulties recognising and naming emotions) has been widely studied in patients with functional disorders and is sometimes addressed as part of treatment.
[30] Migration, cultural and family understanding of illness, are also factors that influence the chance of an individual developing a functional disorder.
[32][33][26] Newer hypotheses have suggested minority stressors may play a role in the development of functional disorders in marginalized communities.
For some people there seems to be a process of central-sensitisation,[37] chronic low grade inflammation[38] or altered stress reactivity mediated through the hypothalamic-pituitary-adrenal (HPA) axis (Fischer et al., 2022).
[39] Commonly, illness-perceptions or behaviours and expectations (Henningsen, Van den Bergh et al. 2018 ) contribute to maintaining an impaired physiological condition.
Iatrogenic factors such as lack of a clear diagnosis, not feeling believed or not taken seriously by a healthcare professional, multiple (invasive) diagnostic procedures, ineffective treatments and not getting an explanation for symptoms can increase worry and unhelpful illness behaviours.
Bodily complaints can be used as a signal to begin incorporating stress reduction and balanced lifestyle measures (routine, regular activity and relaxation, diet, social engagement) that can help reduce symptoms and are central to improving quality of life.
Most affected people benefit from support and encouragement in this process, ideally through a multi-disciplinary team with expertise in treating functional disorders.
The aim of treatment overall is to first create the conditions necessary for recovery, and then plan a programme of rehabilitation to re-train mind-body connections making use of the body's ability to change.
[46] Psychotherapy might be helpful to explore a pattern of thoughts, actions and behaviours that could be driving a negative cycle – for example tackling illness expectations or preoccupations about symptoms.
[50] Despite some progress in the last decade, people with functional disorders continue to suffer subtle and overt forms of discrimination by clinicians, researchers and the public.
Stigma is a common experience for individuals who present with functional symptoms and is often driven by historical narratives and factual inaccuracies.
[51] Part of this stigma is also driven by theories around "mind body dualism", which frequently surfaces as an area of importance for patients, researchers and clinicians in the realm of functional disorders.
[52] Current research is moving away from dualistic theories, and recognising the importance of the whole person, both mind and body, in diagnosis and treatment of these conditions.
[56][57] Directions for research involve understanding more about the processes underlying functional disorders, identifying what leads to symptom persistence and improving integrated care/treatment pathways for patients.
Understanding how stress effects the body over a lifetime,[58] for example via the immune[59][60] endocrine[20] and autonomic nervous systems, is important Ying-Chih et.al 2020, Tak et.