When an OMPSM exists, then we have a case of paranoia. There is no treatment for it. Even if OMPSM could be destroyed, the whole structure of models in harmony with the OMPSM should be rebuilt, and this is impossible.
We will talk now of light forms of paranoia, undeclared as illness. As we know, when a model becomes invariant, all associated models will be distorted to be in harmony with it.
Let's suppose that a brain has a normally built model in accordance with external reality. This model could at some point become totally inadequate in the understanding of external reality due to a change in the latter. The normal solution is the reconstruction of the whole structure of models, but this activity would be beyond the technical capacity of reconstruction of the brain. Due to this, one of the possibilities is to leave the model untouched. In this case, we have a light form of paranoia, which manifests itself as confusion or avoiding discussions connected to the model with problems. Another possibility is to build a shielding model. Shielding models do not modify the inadequate model, but can deactivate it.
As this is not pathological, i.e. no OMPSM exists, the illness could be cured, especially at young individuals. This type of problem (important normal models which do not fit the external reality anymore) can occur at any time in lighter or more serious forms. Prevention of this light form of paranoia can be done with an adequate education.
ETA 14: Suicide
From the general theory we know that a basic requirement of design of the brain is unconditional indefinite survival. However some individuals commit suicide.
From the general theory we also know that models are so strong that they can predict that sooner or later we will die. As this prediction will activate PSM and PSM has no solution, this could destabilize the structure of models. The general theory also shows that the solution is to build a shielding model, e.g. religion. This model sends to PSM a less catastrophic message, which stabilizes the situation. Some religions are so strong that they can determine in their followers no fear of death. These believers can commit suicide very easily, if they have a 'serious' reason, without the possibility of intervention of PSM to block it. Fortunately, the Christian religion is not strong enough to eliminate the fear of death.
This risk of suicide was noticed very early, and this is why religions usually condemn suicide.
Whatever the shielding model would be (religion or another shielding model), PSM will be blocked in case of the activation of a suicide model. The presence of an adequate shielding model can therefore block the PSM, which wants to stop the activation of the suicide model.
A class of suicidal individuals consists of those people that after the disappearance of an entity included in their PSM (a very close person vanishes from their life), they are unable to correct the whole structure of models. The brain gets unstable, all-important models might become unusable and this can lead to suicide.