In 1982 the neurologist Andrew Lees had a dream in which he was sitting on the seabed with a telescope observing a molecular structure above him. As two hydroxyl groups unfurled from a central benzene ring, he recognised the molecule as apomorphine, which William Burroughs had championed in the preface to Naked Lunch as the ‘junk vaccine’ that cured his addiction.

In the intervening years, any interest in Burroughs’s claims had lapsed and the drug was no longer being marketed in Britain. But Lees, following a hunch, managed to secure a supply and injected himself with a 1mg dose. He ‘started to feel pleasantly relaxed’ and developed a ‘strong penile erection’. None the worse for his self-experiment, he obtained permission to administer apomorphine to volunteer patients with advanced Parkinson’s disease. The results were spectacular: all the subjects were unlocked from their helplessly frozen state and ‘could now laugh, talk and stride effortlessly around the ward’. Apomorphine was a therapeutic breakthrough that set Lees on the path to becoming the world’s most highly cited Parkinson’s researcher.

Burroughs might seem an unlikely source of inspiration for a modern clinician. Quite apart from his notorious drug habit, his truculent rejection of authority led him to embrace all manner of what most scientists regard as flimflam, from orgone energy to telepathy, synchronicity and the magical power of the number 23. But what attracted Lees was his dogged empiricism, a term that at different points in its long history has been used in reference to alchemists, quack doctors and stubborn autodidacts as well as scrupulous collectors of evidence. In ploughing his own furrow and making himself the crucible of his own experiments, Burroughs may have succumbed to crank theories, but he also pursued the oblique strategies, with their sometimes serendipitous outcomes, that, in Lees’s view, science needs today more than ever.

Mentored by a Madman is partly a paean to Burroughs’s poison path, partly a series of fascinating vignettes from Lees’s career and partly an impassioned cri de coeur against the stifling of medical innovation by risk management and the pursuit of profit. The threads first intertwine in Lees’s account of being a medical student at the London Hospital in the mid-1960s, performing autopsies by day and ‘Harlem shuffling with a cool yé-yé crowd’ in Soho by night. ‘In rebellious mood’, he picked up the Corgi paperback edition of Naked Lunch and was captivated by the character of Dr Benway, Burroughs’s avatar of the medical profession’s arrogant and sadistic sang-froid. By the mid-1970s he was specialising in neurology in the rarefied atmosphere of University College Hospital, where he took on a second fictional mentor, Sherlock Holmes: ‘Pray give us the essential facts from the commencement and I can afterwards question you as to those details which seem to me to be most important.’

Lees’s sinuous narrative blurs the line between science and literature and erases the conventional distinction between medical and mind-altering drugs. Parkinson’s disease is a chronic disorder of the dopamine system, and the medicines that relieve it are close cousins to such stimulants and psychedelics as amphetamines and LSD. Lees became familiar with their ‘cloud nine effects’, in which patients released from the frozen state could become possessed by gambling, pornography, bingo, romantic infatuations or spending sprees. This ‘candy-land dream world’ of compulsive gratification led him deeper into exploring the mechanics of addiction – or, in William Burroughs’s formulation, ‘the algebra of need’. Nothing he read in medical journals compared in vividness or insight to ‘the unsentimental fieldwork of the arch self-experimenter’.

Lees believes there are many more cures for science to discover, including several that have long been familiar in the Amazon rainforest, folk healing traditions and the drugs counterculture. Yet the 20th century’s flood of new therapies has dwindled to a trickle: the medical industry has become a money machine, in which milking established treatments is more reliable than developing new ones. Apomorphine, since Lees rediscovered it, has been marketed as ‘a Rolls Royce drug that had been previously undersold for the price of a bicycle’ and now costs each patient several thousand pounds a year. The empirical method of pursuing hunches through chance discoveries and self-experiment has been policed to extinction by ‘the sheer volume of inflexible rules, auditing and clinical guidelines’.

In the book’s final part, Lees travels in William Burroughs’s footsteps to the Colombian Amazon to take ayahuasca, the hallucinogenic potion that Burroughs described as ‘the ultimate fix’. Overwhelmed by convulsive nausea and scintillating visions, he lurches into a new dimension of being in which ‘I understand for the first time how during hurricanes, chair-bound victims of Parkinson’s disease can magically override’ their condition. Like his disreputable mentor, he resolves to swim against the tide – to ‘fly crookedly in my curiosity for cures’.