Intended for healthcare professionals

Rapid response to:

Practice Practice Pointer

Recognising and explaining functional neurological disorder

BMJ 2020; 371 doi: (Published 21 October 2020) Cite this as: BMJ 2020;371:m3745

Rapid Response:

Re: Functional neurological disorder - Patients' experience & research

Dear Editor

In their BMJ ‘Practice Pointer’ (1) for General Practitioners (GPs) the authors describe the “Growing evidence … ” around explanations and findings for Functional Neurological Disorder (FND). For patients with experience of FND this evidence raises the question “What could have caused the described corruption of the brain-generated predictions and interference from the limbic system and amygdala?”.

Contributing possibilities must be explored, and there is an obvious one that is not covered: prescribed medications which alter the functioning of the nervous system.

People are developing ‘functional neurological’ issues downstream of having taken GP prescribed antidepressants, benzodiazepines, etc. (on- or off-label, sometimes long-term) for various ‘indications’. As these prescribed drugs are designed to cross the blood-brain barrier and to act on the central and autonomic nervous systems this must surely be significant? We know from recently published work by Hengartner, Davies & Read 2020 (2) that a high percentage of people (46%) experience ‘severe’ withdrawals from antidepressants.

On ‘Comorbidities’ Stone et al mention (in addition to IBS & fibromyalgia)
“Other functional symptoms and disorders, especially those involving chronic pain, fatigue, and memory symptoms” and
“Psychological comorbidities—especially anxiety, panic, and depression … affecting over 50% of patients”

There is a high probability that these patients will have been prescribed antidepressants for ‘anxiety, panic and depression’ (and chronic pain, fatigue etc). Our 2018 ‘Patient Voice’ analysis of public petition evidence (3) has shown that the commonest persistent multiple ‘unexplained symptoms’ of FND overlap strongly with those experienced in antidepressant withdrawal, including dizziness, nausea, pain, fatigue, gastrointestinal problems, palpitations, sleep issues and so on – and these symptoms can persist for months or years, and do not cease (may become worse) once ‘the drug is no longer detectible’ in the system.

This raises important questions (for practitioners and patients) – which do not feature in the list of questions in the article –

• what is the person’s medication history – from the very first prescribed medications, and then over the long term?
• when did the ‘unexplained’ symptoms first become apparent, especially in relation to prescribed medications (i.e. the possibility of adverse medication effects or withdrawal)?
• what other factors may have caused damage to the functioning of the nervous system?

SSRI and SNRI ‘antidepressants’ (taken by 7.3 million people - 17% of the adult population in England, per Public Health England Review 2019 (4)) alter the essential serotoninergic systems – profoundly affecting brain and bodily functions, directly and indirectly via the fight/flight limbic activity. The effects of serotonin are multiple, as described in ‘Serotonin, Amygdala and Fear: Assembling the Puzzle’ by Marco Boccio et al (5) and ‘The Expanded Biology of Serotonin’ by Miles Berger et al (6).

It has been known for decades that antidepressants cause neurological problems; for example, Foster & Lancaster 1959 cases of ‘Disturbance of motor function during treatment with imipramine’ (7), and Peter Haddad et al ‘Antidepressant discontinuation (withdrawal) symptoms presenting as ‘stroke’’(8).

Grosset wrote in 2004 ‘Prescribed drugs and neurological complications’ (9), concluding that “A wide spectrum of neurological presentations may be caused or precipitated by drugs, prescribed and non-prescribed. Doctors have a responsibility in preventing iatrogenic symptoms by careful prescribing, and in identifying drug induced syndromes”.

People who have developed all manner of apparently bizarre symptoms, particularly movement disorders, visual and balance issues, ‘functional’ seizures etc. have been referred to neurology and acquired diagnoses of ME/CFS, MUS, FND, etc. Patients have been researching to try to understand what has happened to them. It seems that they have suffered neurotoxicity, described by Peter Breggin (psychiatrist) in ‘What should we really call psychiatric drugs?’ (10) and Raymond Singer (neurotoxicologist) in ‘Recognising Neurotoxicity’ (11).

In April 2018 we wrote ‘Is the BMJ – and the medical profession that it represents – really ‘listening to patients’ and the public?’ (12) “ is becoming abundantly clear that ‘the evidence’ of prescribed harm is being actively attributed to vague psychiatric diagnoses such as ‘medically unexplained’, ‘functional’ and ‘somatic’ disorders. Patients suffering complex, serious and disabling symptoms - from prescribed drug damage and neurotoxicity - are being directed to websites such as and encouraged to engage in Cognitive Behavioural Therapy (CBT) and acceptance of their mysteriously acquired disability. There is emphasis on locating problems in the patients’ own early life experiences – and socio-economic circumstances - without any reference whatsoever to the all-important life-time ‘medication history’ and its own trail of havoc in the life and health of the patient.”

Our Public Petition ‘Patient Voice’ evidence was included in the Public Health England Review (3) and features in the ‘Patient evidence’ for the National Guideline Centre (13). In their petition evidence, a number of patients (25%) describe MUS or FND diagnoses following antidepressant adverse effects.

If patients ask their GPs or neurologists about the possible cause of their acquired symptoms and disabilities, any suggestion of a link to the ‘effects of medicines, taken as prescribed’ is usually strongly denied, and the patient’s ‘beliefs’ called into question. This, of course, adds further to their distress. The Cumberlege review (14) has highlighted the folly of doctors ‘not believing patients’ – and the resulting ongoing risks to patient safety. “The review panel found that healthcare providers’ dismissive attitude toward patients was underpinned by a reluctance in all parts of the system to collect evidence on potential harms, by a lack of coordination that would allow clinicians and agencies to interpret and act on that information, and by a culture of denial that failed to acknowledge harm and error, impeding learning and safety.”

There will be various reasons why a person may develop functional symptoms; however, in the interests of reducing risks of further harm, and to explore avenues for healing those already harmed, we strongly urge that these clues to the aetiology of FND be fully recognised and investigated with utmost urgency. It is time to openly acknowledge that drugs which are prescribed specifically to alter the functioning of the central nervous system may be the very reason why that nervous system is now presenting as malfunctioning.

(1) Stone J, et al. ‘FND’ BMJ Oct 2020
(2) Hengartner M et al 2020 ‘Antidepressant withdrawal’
(3) Guy A et al. ‘Voice of Patient’ 2018
(4) PHE Review Summary report 2019
(5) Boccio M, et al. ‘Serotonin, Amygdala & Fear’ 2016
(6) Berger M, et al. ‘Biology of Serotonin’ 2009
(7) Foster & Lancaster. ‘Imipramine’ 1959
(8) Haddad P. ‘Stroke’ 2001
(9) Grosset & Grosset. ‘Neurological Complications’ 2004
(10) Breggin P. ‘Neurotoxins’ 2018
(11) Singer R. Neurotoxicity 2015
(12) Brown M et al. ‘Listening to patients?’ 2018
(13) National Guideline Centre. ‘Patient Experience’ 2019
(14) Haskell H. BMJ Report Cumberlege Review 2020

Competing interests: No competing interests

27 October 2020
Marion Brown
Stevie Lewis, Alyne Duthie, Fiona French, Sharron Hudson, Beverley Thomson, Ann Kelly, Janette Robb, Dierdre Doherty (Voice of Patient research group)