Cannabis intoxication can induce anxiety attacks of varying strength. Such attacks of panic anxiety are probably a relatively frequent side-effect; they are believed to be more common in occasional smokers or smokers who ingest a larger amount of THC than they are used to.
Further, the anxiety attack may signal the beginning of a protracted panic-anxiety syndrome which does not differ from panic-anxiety illness that begins in some other way. Cannabis smoking can also provoke a relapse into panic-anxiety syndrome.
On occasion, experiences of unreality, which are a common feature of cannabis intoxication, may become so strong that they dominate the experience of intoxication. These anxiety-like “depersonalisation syndromes” generally abate rapidly after intoxication. There are, however, a number of published case studies where the feelings of unreality have persisted over a very long period after being provoked; in some cases, the disorder has had an invalidating effect and has been very difficult to treat.
In a survey of 117 patients with chronic/long-lived depersonalisation syndrome, cannabis was found to be the third most frequent provoking factor.
One of the contradictory characteristics of cannabis is that it can both relieve anxiety and give rise to pronounced attacks of anxiety and panic. Such anxiety attacks are probably the most common side-effect experienced by smokers of cannabis (), and all habitual smokers have themselves had them or seen their friends affected by them. While the condition is more frequent in beginners, it also occurs in more experienced users. This side-effect is almost certainly dose-dependent, although it is also to a large degree dependent on the mental condition of the smokers and on their perception of the social setting in which they find themselves. This is a well-known phenomenon in abuser circles, but it has also been demonstrated under experimental conditions (). In a survey of 200 cannabis abusers, 22 per cent stated that they had experienced panic anxiety on at least one occasion ().
Like other attacks of panic anxiety, these attacks can be very frightening, with a strong feeling of losing control, going mad, and so on. Nevertheless, those affected seldom seek professional help – instead, the situation is dealt with within their circle of friends. The condition is generally short-lived, its only consequence being that the persons affected are subsequently more careful with doses and with the social setting in which they smoke, or that they stop using the drug completely.
However, an anxiety attack sometimes marks the beginning of a protracted panic-anxiety disorder which is indistinguishable from panic anxiety that has begun in some other way (). Cannabis can also provoke a relapse into or a deterioration of panic-anxiety disorder (). In some cases, professional help may be required ().
Feelings of unreality are often part of the experience of an anxiety attack, and this holds true for cannabis-induced anxiety attacks as well. In cannabis smokers, though, these feelings of unreality may become more profound in nature, and sometimes they dominate the negative experience (). When these symptoms are provoked by cannabis, they are short-lived – as are like anxiety attacks in general.
When feelings of unreality dominate the symptom picture and become long-lived, we usually talk of “depersonalisation syndrome”. This condition appears to be closely related to the anxiety disorders, but there is a lack of consensus as regards its classification. From a psychodynamic point of view, it is seen as a defence against unbearable anxiety. This condition is rarely encountered as an independent disorder in general psychiatric practice.
It is worth noting, not least in view of the rarity of the condition, that a number of cases of prolonged depersonalisation syndrome induced by cannabis smoking have been reported in the scientific literature. Several of these cases have been difficult to treat ().
Prolonged depersonalisation syndrome subsequent to cannabis smoking (as opposed to depersonalisation experiences during intoxication) is rarely mentioned in reviews and summaries of the harmful effects caused by cannabis, and thus it was not primarily by studying the research literature that I became aware of the connection between these conditions. A patient who was referred to my general psychiatric practice exhibited the following clinical picture:
A district doctor referred a young man to me with “anxiety disorder following cannabis psychosis”. It transpired that the young man had not had a psychosis; what he had in fact suffered from was a severe attack of anxiety the last time he had smoked marijuana – roughly six months previously. After this attack, an anxiety syndrome (panic anxiety) had persisted and progressively become more dominated by feelings of unreality. The patient had smoked cannabis fewer than ten times in all, his social situation was very stable, and he had no history of mental problems and no hereditary tendency towards mental illness. Three years later, I was able to conclude that the patient’s feelings of unreality had become a constant companion of his. Sporadically occurring anxiety proper had made its appearance, and the patient’s tendency towards social phobia complicated the situation. The patient was not handicapped by the symptoms, but they were a great nuisance to him and also a cause of worry. In addition to the unpleasantness of having a symptom of this kind constantly present, certain important social activities were made much more difficult. Fo r several years, the condition resisted all attempts to treat it.
Daphne Simeon and co-workers have recently, in an informative survey (), examined 117 cases of depersonalisation syndrome – which is a larger number than I have found in earlier reports. When going through these cases, they found that the majority of the patients were suffering from a chronic condition that had persisted for 15 years on average. In no fewer than 57 of these patients, no provoking factor could be identified. The second most common provoking factor was found to be stress (29 cases), and in third place was cannabis (15 cases). A majority of the patients had a life story involving shorter or longer periods of other mental illness, mainly depression and anxiety.
Selections from the book: “Adverse Health Consequences of Cannabis Use. A Survey of Scientific Studies Published up to and including the Autumn of 2003”