Suspiciousness is an automatic reaction of brute force to passivity and passive fear. Experiencing chronic fear from passivity and attempts to external control, subconscious includes suspiciousness in the hope provoke activity and destroy fear.
Depression and suspiciousness are very related to passivity. To cure depression, you need to take an active position and start making decisions at all costs. Decisions can be any, right or wrong. No matter, the main thing-independent. Passive pleasures are particularly dangerous for humans.
The novel "Anna Karenina" is a symbol of neuroticism and ode to fear. Neurotics are very afraid of everything new, afraid of the future, because the unknown can break their glass house of illusions. The locomotive, as a symbol of the unstoppable future, breaks into the illusion and destroying it, in the end, kills Anna, and maybe only her illusions. After all, what killed Anna in the hands of her son Seryozha we see at the end of the novel only as an ordinary toy.
This is the main symptom of neurosis and depression - obsessive suspicion, paranoia, distrust and the need to invent fears and problems. Paranoid fears loop in the head of a person, he begins to invent his own fear and goes crazy from them.
The meaning of" Chamber number 6 " Chekhov is that a person falls into hell from fear. Private mistrust, reinforced by the immaturity of the spirit and idealism make life in a mental theatre of suffering. Running away from the illusion of fear and paranoia, a person gets deeper and deeper into the infernal swamp.