Cannabis is a substance whose toxic and medical properties are the subject of ongoing discussion. One could simply conclude that the medical properties of certain compounds found in cannabis, including non-psychoactive ones, have prompted research and the development of pharmaceutical preparations, while its toxic properties are related both to the cannabinoid compounds themselves and to the smoke produced by combustion.
There are also its effects on the brain, and therefore on mental functioning, which are at the basis of the illegal status of cannabis.
Let us begin with its effects on the various organs and systems, leaving the nervous system for last.
Cannabis cigarette smoke, independently of the effects of cannabinoids, produces effects on the respiratory system similar to those of tobacco smoke. In qualitative terms, the impact is greater because the smoke is inhaled more deeply and because “carcinogenic hydrocarbons” produced by combustion are present in greater quantities, with a higher proportion being converted into carcinogenic compounds through a process of enzyme induction.
Clearly, the number of cigarettes consumed is lower, so the toxicity is more “intense” but lower in terms of overall quantity. The amount of “tar” from four cannabis cigarettes per day is equivalent to that from 20 tobacco cigarettes per day.
In other words, habitual consumption of a “small” amount of cannabis should not lead one to assume that the risk associated with inhaling smoke is negligible, because it can be equivalent to that produced by many tobacco cigarettes.
The active compounds in cannabis have a negative effect on sperm motility and on their ability to fertilize an egg once they come into contact with the egg cell. Hormonal alterations have also been documented, although different individuals probably do not have the same sensitivity to this effect.
Hormonal alterations have also been observed in women, with the possibility of interference with hormonal stimulation procedures used in assisted reproduction.
The actual impact on fertility and birth rates nevertheless remains to be established, since these alterations alone do not allow firm conclusions to be drawn. There are also lifestyle-related factors, as well as confounding factors associated with patterns of multiple substance use, pharmacological treatments, and other diseases.
An immunosuppressive effect is also possible. In HIV-positive individuals, this has been documented as increased susceptibility to herpesvirus infection.
Cannabinoids obviously have other effects on various organs and systems as well. For the sake of simplicity, the main established toxic effects are summarized here.
Certo. Mantengo il registro medico-divulgativo e cerco di rendere in inglese anche le sfumature del testo originale, senza trasformarlo in una traduzione eccessivamente letterale.
Scrittura
Mental effects
With regard to mental effects, the available data do not always allow us to establish whether there is a cause-and-effect relationship. For example, saying that a certain percentage of cannabis users suffer from depression does not establish whether these individuals are predisposed to depression independently of cannabis use, or whether cannabis itself causes it. The same applies to more serious illnesses such as psychosis.
The only way to better understand this causal relationship is to study groups of users over a number of years and determine whether they develop mental illnesses more frequently, while also comparing them with non-users and with the population as a whole. For example, it may be observed that the incidence of psychosis increases over time compared with non-users, while the number of cases of depression does not change as the number of cannabis users increases. These differences can be seen quite clearly by comparing periods in which a substance becomes widespread because it is “fashionable” with periods in which its use declines because it is prohibited.
In the case of cannabis, it can be said that users are psychiatrically at greater risk of psychosis—a fact that has been demonstrated—even if this is not necessarily caused by cannabis itself. At the same time, however, the risk of developing psychosis increases with increasing levels of consumption: heavy, regular cannabis users have a risk that is approximately 200% higher.
Cannabis does not appear to actually produce entirely “new” cases of psychosis, because the spread of the substance has not resulted in an increase in the overall number of psychosis diagnoses. What does increase, however, is the number of patients with psychosis who have a history of cannabis use or who continue to use cannabis after the onset of their mental illness.
Cannabis may also contribute to a progression from a “mild” level of severity—such as a personality disorder or borderline-type conditions with preserved social functioning—to fully developed forms associated with social maladjustment.
Another relevant finding concerns the younger age at which the illness begins. People who use cannabis and are predisposed to psychosis therefore tend to become ill earlier. This can make a significant difference, since it may be assumed that a disorder affecting an adolescent brain corresponds to a more severe illness, greater chronicity, or a worse long-term course.
When evaluating these factors, however, the specific diagnosis should also be taken into consideration, namely schizophrenia versus bipolar psychosis, which have different baseline prognoses.
People with bipolar psychosis generally continue to use cannabis even after the illness has begun, but by their nature they tend to have a better recovery. Acute forms of psychosis are more unstable in terms of behavior, with a greater tendency toward impulsivity and aggression, as well as greater fluctuations in mood.
Cannabis and other mental disorders
As for other mental disorders, the exact nature of the relationship is not clear, but cannabis tends to “season” them in a fairly distinctive way.
This “seasoning” can be seen in the type of symptoms that emerge—derealization and depersonalization, pseudohallucinations (that is, vivid quasi-hallucinatory or obsessive phenomena experienced as occurring inside one’s head), and perceptual distortions—as well as in greater instability in the course of the disorder.
In panic disorder, this can be particularly frightening. The person is already frightened by the state they are in and may become extremely concerned about some of these more unusual, “neurological,” so to speak, symptoms, which are in fact less common in panic attacks occurring without cannabis use.
The typical course of panic that begins while under the influence of cannabis, or even after just “a few puffs,” involves a very intense acute phase, with withdrawal and isolation, lowered mood, distress about one’s own mental state, and tangled or rapidly overlapping thoughts that the person cannot seem to stop.
The person typically fears that they are “going crazy” and losing control of their contact with reality and of their mental faculties.
Sometimes this predominantly anxious state, accompanied by perceptual disturbances—as though it were a lingering effect of the cannabis experience—precedes more severe forms of illness.
In such cases, there is usually a state of perplexity rather than outright fear, accompanied by a search for meanings that seem to emerge briefly but remain unclear, as though something were happening around the person but they were unable to understand what it meant.
These are two different conditions requiring radically different treatments. Nevertheless, it is always advisable for treatment to begin as early as possible, or at the very least for an assessment to be carried out promptly.