In 1772, Joseph Priestley, natural philosopher and erstwhile teacher at the dissenting Warrington Academy, synthesised nitrous oxide, which he called ‘dephlogisticated nitrous air’.
In 1799, Dr Thomas Beddoes founded the Pneumatic Institution in Bristol to investigate the effects of recently discovered medical gases on the bodies and minds of volunteers. Sir Humphry Davy, later President of the Royal Society, was among those at the Institution who described the effects of inhaling nitrous oxide. It was later nicknamed ‘laughing gas’, due to its obvious and replicable psychoactive properties.
Following a busy few months, Beddoes published an exposition of the Institution’s emerging research, Notice of Some Observations Made at the Medical Pneumatic Institution (1799). He summarised the institution’s enthusiasm for the potential therapeutic effects of nitrous oxide, writing that their experiences:
‘… emboldened us to attempt the cure of diseases proceeding from a defect of nervous energy, analogous to that which takes place in palsy. We accordingly looked out for a paralytic patient, and were only anxious that his complaint should not depend upon visible organic lesion’. (p.18)
He then described two case reports of patients who underwent multiple inhalations of the gas over several weeks:
‘The first patient that offered was a man aged twenty-six, who after a course of excessive debauchery, especially with regard to fermented liquors, had been deprived, ten months before, of the power of one side … The progress of amendment was remarkable. The power of the affected side progressively returned; and at last he would grasp things without a tremor of his affected arm’. (p. 19)
‘… another patient, afflicted with the loss of power to one side, and in other respects as shattered a human creature as can easily be met with … received considerable amendment. He can now walk a little without crutches; and the improvement of his general health has more than kept pace with the abatement of his paralytic affection … He emphatically said that he found himself a great deal—a great deal stronger. On coming to us he required support, when he moved, beside that of his crutches. Now he walks down stairs without even a stick’. (p. 20)
These descriptions, from the close of the 18th century, appear to represent the first medical descriptions of the experimental use of a psychoactive substance in the (successful) treatment of what we might now call motor functional neurological disorder (FND).
Nitrous oxide faded into obscurity after the Institution closed, and it took another 50 years before its applicability as an anaesthetic was understood. In the 1940s there was re-emergent fringe interest in the use of the gas in abreaction therapy for what we might now call FND; yet, once again, it seemed to fall out of fashion as a treatment for neuropsychiatric disorders.
The relationship between nitrous oxide and motor FND is likely to be complicated, with inhalation sometimes associated with transient motor symptoms, and some case reports describing the emergence of FND post-anaesthesia. Nevertheless, given recent interest in the use of psychoactive compounds such as ketamine and psychedelics as potential treatments for FND, Dr Beddoes’ historical precedent is timely.
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