Habit cough: A pseudo-asthma syndrome

Chronic cough is commonly attributed to asthma. The habit cough is a functional disorder, often treated as asthma. However, there are differences that should be recognized. Cough from asthma will be stopped with a short course of oral corticosteroid1, however, habit cough responds to no pharmacologic agents. The persistent coughing, without an identifiable cause, that is the characteristic of this disorder troubles the patient, family and physicians whose diagnosis and treatment are sought. The morbidity of this disorder is increased by unsuccessful medical interventions consisting of diagnostic procedures and therapeutic trials for other causes of cough.

History

The known history of the habit cough begins in the 17^th century. A book in the year 1694 by Franciscus Mercurios (1614-1699), a Flemish physician, alchemist, kabbalist and writer, published as a book, The Spirit of Diseases or Diseases from the Spirit Laid Open in Some Observations Concerning Man and His Diseases. It included a broad range of topics. However, the one of interest for the subject of this commentary reads as follows: ‘…Habitual Cough, which often continues after the first cough, which was caused by the cold, is gone …. and the Habitual Cough often proceed’2. A medical textbook from 1685 by Thomas Willis (1621–1675) described an adult woman with ‘a violent dry cough following her day and night unless she was fallen asleep’, a description that would fit the habit cough diagnosis today3. Habit cough was also recognized in the 19^th century in the writing of Charles Creighton (1847-1927), a British physician and medical author who was highly regarded for his scholarly writings on medical history. In his 1886 book, Illustrations of Unconscious Memory in Disease, he described, ‘…a habit cough – a reflex effect persisting after the cause is gone …. or an acquired habit….’ He went on to state, ‘…the treatment of it is to break the habit ….’4.

In 1963, Dr Leslie Bernstein in Iowa City reported a 12 yr old girl with a particularly harsh non-productive cough that the mother likened to ‘the cry of a Canadian goose’5; the mother of the girl estimated 30-60 coughs/h with frequent spasms during the day but the complete absence of cough once asleep. Morbidities included the inability to remain in a classroom and loss of social activities. Dr Bernstein suggested that the cough appeared to be a ‘respiratory tic and may be precipitated by emotional trauma’. While Dr Bernstein’s observations were based on that one patient, Dr Bernard Berman, a Boston allergist, published in 1966 his experience with 6 children over a five-year period, three boys and three girls between the ages of nine and 13 yr, afflicted with habit cough6. Neither tics nor serious underlying emotional problems was apparent to Dr Berman who described curing those children with what he called ‘a simple modality of therapy’ that required an understanding and experience in the art of suggestion.

In 1991, a manual review of medical records at the University of Iowa Paediatric Allergy and Pulmonary Clinic identified nine patients with the diagnosis of habit cough. All had been extensively evaluated by their referring physicians. Various medication trials provided by the referring physicians were ineffective in the control of the cough. All were coughing when seen and the coughing was stopped in all during 15 min of applied suggestion therapy7. Seven of the nine could be contacted a median of 3.6 yr (up to 9.4 yr) after the clinic visit. Six were asymptomatic; one had recurring minor self-controlled symptoms five years after the clinic visit. The assessment of the seven by a standardized SCL-90-R psychological questionnaire identified no serious psychological issues.

Habit cough diagnosis is based on the clinical presentation of a child or adult with an unusually frequent daily cough that is non-productive and is absent once asleep. The diagnostic criteria based on the clinical presentation were utilized at the University of Iowa in the USA8 and at the Brompton Hospital in London England9. Although habit cough may co-exist with another respiratory problem, diagnostic tests other than screening spirometry and a chest X-ray are not justified.

Treatment by suggestion therapy continued as the standard of care at the University of Iowa Paediatric Allergy and Pulmonary Division. Examination of the results over a 20 yr period, 1995-2014, was published in 20168. One hundred and forty children were diagnosed during that 20 yr period, with an average of nine per year during the last half of that period. Nine per year over six years was also seen at the Brompton Hospital in England. There was a seasonal decrease during the summer months in the Iowa study. Of the 85 seen and heard coughing during the clinic visit, coughing was stopped in 81 by whichever of the division faculty saw the child in the clinic that day.

In February 2019, suggestion therapy was provided by video conferencing to a 12 yr old girl with a chronic cough for three months consistent with habit cough. Cough was stopped, and subsequently, a video of that teleconference became incorporated into a website created by the father of the girl, www.habitcough.com. A copy of the video was also placed on YouTube, https://youtu.be/jnQUvD8Qdj0. We became aware that those with chronic cough consistent with habit cough who watched the video essentially experienced suggestion therapy by proxy and stopped coughing10. From 2019 to 2023, e-mails from more than 90 parents and 22 adults from 18 countries, including five children and three adults from India, described cessation of chronic cough from watching the video11. All were contacted and confirmed that the cough was consistent with habit cough.

Controversies

Prompt cessation of a prolonged chronic cough by something called suggestion is likely to be associated with an element of incredulity. Controversies are then to be expected. A 2020 Chest Guideline and Expert Panel argued against the diagnostic term, habit cough and instead supported that somatic cough disorder should be used12. The value of that diagnostic term was not apparent and the rationale for the recommended change in terminology was obscure. The terms ‘psychogenic cough and tic cough’ were also discussed in the guideline. A specific suggestion was that the presence or absence of cough during night sleep should not be used for diagnostic criteria12. However, the absence of repetitive daily cough once asleep is uniformly observed in multiple reports since 16933-6,9,13-15, while cough disturbing sleep is common in organic respiratory disorders. The absence of the troublesome repetitive non-productive cough when asleep in the habit cough disorder is so consistently observed that the absence when asleep is a sine qua non for the diagnosis. Nomenclature for the disorder, habit cough or tic, was debated by a paediatric pulmonologist and neurologist in 201916-19.

Habit cough has generally not been recognized in adults. However, over 40 per cent of patients referred for specialist evaluation have been described as a distinct group with idiopathic cough20,21. This estimate of 40 per cent has been repeated in subsequent reviews22,23. A behavioural component, such as habit cough, has not been generally considered in those adults with idiopathic chronic cough. Communications from 22 adults described a frequent chronic non-productive cough that was absent once asleep24. That description was identical to the habit cough in children. Most of those adults had extensive evaluations for other causes of chronic cough and received trials of various medications without benefit. Moreover, those adults responded with cessation of cough from viewing the suggestion therapy observed on www.habitcough.com or https://youtu.be/jnQUvD8Qdj0.

Thus, there should no longer be controversy regarding whether habit cough occurs in adults. The only question is the prevalence of adults with habit cough currently considered to have an idiopathic or refractory chronic cough; those adults, like the children could possibly respond to suggestion therapy. We will not know the answer to that until referral centres for adults with chronic cough first identify how many of the 40 per cent of patients with chronic cough meet the criteria for habit cough, a daily repetitive non-productive cough that is totally absent once asleep. A placebo-controlled trial of the video that has been effective in 22 adults and more than 90 children would then provide confirmation for our observations and benefit an as-yet-unidentified number of adults.