Can drugs cause a psychosis, or only unlock it? There have been many reports, that recreational drug use can cause psychosis. Some cannabis users report experiencing psychosis (sometimes permanent) immediately after use. Some methamphetamine users also report psychosis symptoms, like hearing voices, which are also sometimes permanent.

A lot of people, who like to defend cannabis (or even methamphetamine) like to argue that cannabis is unable to cause psychosis, it can only trigger or unlock it.

Presumably, there already was something wrong with this person and cannabis only unlocked the problem, but it was going to be unlocked eventually by something anyway.

Is there any difference between "unlocking" and "causing" a psychosis?

Is it true, that you can have a "sleeping psychosis", which is just waiting for a disturbance to present itself?

Is it simply a case of genetic predisposition, which people wrongly equate with having "sleeping psychosis"?

I am aware about the controversy regarding schizophrenia and cannabis, I am mainly talking about psychosis.
Can drugs cause a psychosis or only unlock it



Drugs can cause acute psychosis, but are not associated with a precipitation of a chronic psychotic state. Animal studies have shown that various drugs (including LSD, ketamine and amphetamine) can induce acute psychosis in genetically non-disposed animals (Ham et al., 2017). However, in general, drugs do not induce a state of chronic psychosis associated with for example schizophrenia. Chronic amphetamine use by non-psychotic individuals sometimes do develop a paranoid state resembling a psychosis, but it usually dissipates upon withdrawal from the drug. Former amphetamine addicts do remain hypersensitive to the psychotomimetic effects of AMPH, even after years of abstinence. There are also anecdotal reports that ‘physical or psychological stress’ can precipitate a psychotic episode in a portion of former addicts. This suggests that chronic amphetamine use produces a long-lasting change in some neural system(s) involved in the psychotomimetic effects of AMPH (Robinson &amp; Becker, 1986).  



  Is there any difference between "unlocking" and "causing" a psychosis?  



I would say that in genetically predisposed people (Owet et al., 2007) you could call it unlocking, but I think that everyone has a certain chance of getting it. Some people need more extreme environmental factors (low genetic disposition) and others with a high predisposition are at higher risk of developing psychosis.



  Is it true, that you can have a "sleeping psychosis", which is just waiting for a disturbance to present itself?  



As said, when people are genetically predisposed, environmental factors, such as childhood trauma (Morgan &amp; Fisher) may relatively easily trigger a psychosis. You could call that a 'sleeping psychosis', but as with the term 'unlocking' you could just as well label it genetic predisposition I think. It's a matter of semantics I guess. 



  Is it simply a case of genetic predisposition, which people wrongly equate with having "sleeping psychosis"?  



So yes, I think so. I don't, however, would call it 'wrongly'. It's more popular scientific language to call it sleeping or latent. But at the same time it also charges it with something 'inevitable' or a 'looming (sleeping) creature in the dark'. That's why I would definitely prefer to call it genetic predisposition, but in certain environments that term may also cause fear ('oh no, it's embedded in my genes!). 

References
- Ham et al., Exp Neurobiol (2017); 26(1): 11–24
- Morgan &amp; Fisher, Schizophrenia Bulletin (2007); 33(1): 3-10
- Owen et al., Schizophrenia Bulletin (2007); 33(4): 905–11
- Robinson &amp; Becker, Brain Res Rev (1986); 11(2): 157-98