How cannabis helped understand mental illness

share this article

Early 19th-Century France saw the genesis of an interesting if controversial approach towards understanding the origins and nature of psychosis. Jacques-Joseph Moreau was at the forefront of modern psychiatry.

As Vincent Van Gogh's 'The Starry Night' (1889) seems to depict, a psychotic state of mind is very similar — or, looks eerily similar on canvas, at any rate — to a dream state. | Wikipedia


Self-Experimenters: Sources for Study” is a 2003 bibliographical book authored by Arsen P. Fiks. It provides an exhaustive list of scientists across various branches of medicine who have experimented on themselves. The entry for the French psychiatrist Jacques-Joseph Moreau (1804-1884), rather cryptically notes the following under “conclusion/ contribution”:

Informed his friends about his feelings in time of experiment. As a result the artistic community of Paris had a short hasheesh epidemic.

This less-than-scientific entry for Moreau is a reflection of the cultural impact of his experiments. Moreau’s “Club des Haschischins”, a 19th-Century Parisian group dedicated to the exploration of drug-induced experiences, counted the likes of Charles Baudelaire, Alexander Dumas and other French literary intellectuals as members. His influence extends beyond counterculture to early psychopharmacology, to the characterisation of the effect of cannabis on mental health, to the theory of dissociation of ideas and to the theory of mental degeneracy. He was also a progenitor of the chemical modelling of psychosis; while examples abound of physicians using cannabis to cure mental illness, Moreau’s work on modelling and understanding mental illness using cannabis was novel. 

Source: Wikipedia

Jacques-Joseph discovered hashish on a trip to the Orient, and experimented with other psychoactive substances to decipher a link between insanity and dreams. He saw the potential in psyhoactive substances for treating mental illnesses, thus pioneering the advent of modern psychopharmacology.

Moreau found that the frenetic rush of unconnected thoughts one experiences during a “trip” was no different from the dreams we experience in natural sleep

France was a birthplace of modern psychiatry and in the early nineteenth century, psychiatrists (called alienists) there enjoyed many privileges. An asylum system had been set up and integrated the new specialty into the medical apparatus of the state. However, by the late 1830s, the profession was in something of a crisis. To prove the necessity for specialised medical expertise in managing mental health, psychiatrists had long been trying to find a physical origin of mental illness. Attempts using phrenology (the study of craniums or heads to determine character) and locating brain lesions through autopsies had failed. Most alienists had given up on finding proof of the physical origin of mental illness and acquiesced to an uneasy position of taking organic lesions as granted; in any case, belief in physical cause had little to do with treatment. The exigencies of day-to-day practice meant that most mid-19th-Century alienists would have agreed that it was impossible to eliminate philosophical considerations from the study of madness as long as its symptoms included acts of questionable morality. Everyday practice had largely been learnt from the concierges that used to manage asylums earlier. A “scientised” version of the old so-called “moral treatment” was developed by pioneers like Pinel and Esquirol accompanied by medical remedies such as blood-letting, cold baths and purgatives.

The profession also faced challenges from those who emphasised treatment methods not grounded in physicalist theory. For example, Jean-Pierre Falret emphasised the religious roots of moral treatment and raised the prospect of collaboration with religious healers, thereby threatening the still-embryonic “scientisation” of the alienist practice. Another challenge came from Francois Leuret who sought to reinvigorate a particularly barbaric brand of violent moral treatment.



Moreau’s career was illustrative of these mid-nineteenth-century crises in French psychiatry. Born in Montrésor to a mathematician-soldier father, he studied in Tours before moving to Paris, where he obtained his medical degree. In 1826, he became an intern at Charenton asylum under Esquirol, traveling the world with patients to whom Esquirol had prescribed travel. Returning to France in 1839, he worked briefly at the Bicêtre asylum before moving to Esquirol’s private asylum at Ivry after the latter’s death in 1840.

Having learnt of hashish as a therapeutic visiting Egypt, he began his experiments with hashish at Bicêtre. His experiments with hashish moved on a path radically different from its use in therapeutics characteristic of the work of O’Shaughnessy in India and fellow Frenchman Aubert Roche in Egypt.

I saw in hashish… a significant means of exploring the genesis of mental illness… It could solve the enigma of mental illness and lead to the hidden source of the mysterious disorder we call “madness” ... I had only to transfer the main characteristics of delirium to those of hashish intoxication and apply …insights… [of] self-observation… To comprehend the ravings of a madman, it is necessary to have raved oneself, but without having lost awareness of one’s madness, without having lost the power to evaluate the psychic changes occurring in the mind… hashish gives to whoever submits to its influence the power to study in himself the mental disorders that characterise insanity.

In his book Du hachisch et de l'aliénation mentale: études psychologiques (translated as Hashish and Mental Illness in 1973) Moreau made bold claims. The first was that all mental illnesses owed their origin to a primary mental change, identical in all cases; the cause being what he termed as “excitement”. Through his ability to produce in himself what called “all forms of mental illness” with the aid of hashish, he attempted to demonstrate that while classification may be useful, it was an incorrect project; making the case for a singular mental illness and a single cause. Moreau saw what he called l’excitation maniaque (manic excitement) as the fait primordial (primary fact) and cause of all mental illnesses.

In his experiences with hashish he noted the weakening of the ability to direct thoughts at will, the succession of true and false ideas which became impossible to discern, and the error in mental timekeeping which resulted from the quick succession of thoughts; postulating that these are fundamental to what goes on in the minds of the mentally ill. This surplus of mental energy made the mind subject to a variety of different emotions and an improper association of ideas. To Moreau, the point of departure of mental illness was this désagrégation of ideas, which he variously called the “exaggerated molecular movement in nervous excitement”, a “molecular disintegration of intelligence”, an intellectual disintegration and “rapid dissolution of capacity to think” which results in inability to discern dreams from reality.

Moreau attacked the idea of an organic lesion in the brain. To him the lesion was functional, rather than structural, like “the intimate texture of a rope to which one applies vibrating motions of variable intensity”, and he put it down to changes in blood circulation. He argued that the damage to the faculties is in the nature of a general upheaval of the intellect and judgment, and saw the damage to the emotions, impulses, and to the senses as resulting exclusively from damage to the intellect.



Arguing that hallucinations were the fundamental characteristic of all mental health symptoms and that were akin to dreaming, Moreau saw the cause for hallucinations in the same general upheaval of the faculties which he calls “excitement“. To him, hallucination resulted from to a confusion between the ideas of the inner world and those of sensory perception that characterise the intermediate state between sleep and waking. Through these arguments Moreau drew the conclusion that there is no psychological distinction between the dream state and the delirium of insanity.

Two modes of mental life are known to man. The first results from our relationship with the external world… the second is only a reflection of the first… Sleep is like a barrier raised between these two lives: the physiological point where external life ceases and internal life begins… But it happens that… these two lives tend to become confused… An imperfect fusion occurs, and the individual without having completely abandoned reality and the individual… belongs… to false sensations, erroneous beliefs.

Arguing that it is wrong to ascribe too much importance to the nature of the hallucinations, Moreau said that there was no such thing as a hallucination but only a hallucinatory state; it is the presence of the latter that is characteristic of mental illness, and not the nature of the former. To him, the ability to reason about the irrationality of one’s hallucination did not imply that one is sane.

The mid-century consensus in France was that dreams were entirely involuntary; if hallucinations were identical to dreams, alienists could ensure professional privilege by arguing these were of physical origin. However, Moreau’s work was really an attack on Leuret’s barbaric moral treatment.


Leuret had argued that mental illness was linked to disorders of the passions and ideas and that moral treatment was the only method to correct the erroneous notions of the insane. His particular methods of moral treatment relied on intimidation and sometimes violence; Leuret took an almost perverse pleasure in the revulsion his methods provoked among other alienists. Despite alienists trying to find spiritualist ideas in his work so as to discredit him, Leuret did not deny that insanity was linked to organic changes in the brain, but emphasised that somaticist etiology (the theory that the mind is constituted by the physicality of the individual) had little to offer to the design of therapy, which he believed was better directed at passions and ideas rather than bleeding, purgatives and pharmacology. Even the most ardent of believers in somaticism applied some form of moral treatment in equal measure with therapy as it had proved to be effective.


“[Moral treatment] leads many to struggle to conceal and overcome their morbid propensities; and, at least, materially assists them in confining their deviations, within such bounds, as do not make them obnoxious to the family." ~ Samuel Tuke, Description of the Retreat, 1813


The alienists however attacked Leuret for his emphasis on the disconnect between etiology and therapy; this threatened the “scientific” status of their methods. His particular brand of moral treatment also threatened to take psychiatry back to barbarism of eighteenth-Century asylums. Moreau was shocked at Leuret’s use of a cold douche to browbeat a patient and quickly became one of his most vocal critics. He objected to Leuret’s claim that hallucinations cannot constitute a psychosis in themselves as they are found in people who appreciate and judge them rationally. Objecting to the idea that madness could be treated by the same means used to correct the errors of sane men, Moreau argued:

Can anyone find a single case of hallucinations cured by reasoning? If you fail to find one in a person without education, in a less cultured mind, do you at least succeed when you address yourself to educated men versed in matters psychological, to philosophers for example or to physicians?

This was an attempt to make a case against barbaric moral therapy. If it were not the particular nature of the ideas but hallucination in itself that constituted mental illness, how could one treat it by browbeating patients to recant their evil visions?

Besides being an interesting story of the use of cannabis for psychiatric experiments, the story of Moreau demonstrates that controversies in mid-nineteenth century French psychiatry went beyond professionally self-serving debates about the physical origin of mental illness. Most alienists believed in physical lesions though they may have differed on their exact nature. The challenge was to ground their diagnostic and therapeutic methods in etiology, and establishing physical cause was not the only means of doing so. Moreau sought to model mental illness using cannabis to provide an explanatory framework grounded in etiology, and to banish barbaric moral treatment by showing how it would not work.

share this article
This article is closed for comments.
Please Email the Editor