Emotional Problems, Psychological Or Biological

Is the natural state of a human happy and if so does mental illness, which leads to depression require fuel to shift one's mood from a natural state to a depressed one? Does mental illness, like fire, need fuel to maintain itself? Could mental illness be fueled by self destructive coping mechanisms? Consider a person who has suffered tragedy and turns to drink to cheer himself up. Alcoholism is likely to create more problems and more depression. If the person then copes with this increased depression with alcohol a vicious cycle is created which fuels the unhappy state of the alcoholic.
Mental illness may be fueled by the misguided efforts of the mentally ill to overcome their problems. If a mentally ill man's efforts to help himself actually make his illness worse then he becomes caught in a vicious cycle fueled by his efforts to help himself. The more the person tries to protect himself against a deteriorating situation the worse he makes the situation and the worse the situation becomes the more he tries to protect himself against the situation.
An example of this is the way the mentally ill cling to paranoid beliefs in order to defend themselves against the threat they believe they face. The best way to understand this is to imagine one came home late at night and thought one saw a man with a knife in the shadows next to the house. One could tell one's family and they could say, it's dark, you had a hard day, you probably didn't see anything forget about it. But because of the danger of not believing it if it's true, you might be reluctant to accept that there is no threat. Instead you might keep yourself in a constant state of alert. As someone once diagnosed as paranoid schizophrenic, I can testify that, I personally was in a constant state of alert because of the paranoid beliefs that I used to have.
Paranoia leads to anxiety. Geoffrey Cowley wrote an article in Newsweek (2/24/03) called Our Bodies Our Fears in which he quotes Afton Hassett, an expert on psychosomatic illness as saying:
Even at low levels, anxiety causes muscle tension, which in turn leads to aches, pains and twitching eyes.
He also writes how anxiety can damage the brain and affect memory. What happens to a paranoid person whose memory deteriorates and gets strange aches, pains and twitches? He might conclude that he is being poisoned. He may be always on the watch for whoever he thinks is poisoning him.
What are the consequences of paranoia and being in a constant defensive state? One would expect one's adrenaline levels to go up. Cushing, in 1913, maintained that "psychic conditions profoundly influence the discharges from the glands of internal secretion" (Cushing H. Psychiatric disturbances associated with disorders of ductless glands. American Journal of Insanity 1913;69:965–90.). He discovered hyperadrenalism and described the syndrome, now named after him, characterized by the presence of "sleeplessness, inability to concentrate, visual disturbances" and "fits of unnatural irritability alternated with periods of depression" (Cushing H. Basophil adenomas of the pituitary body and their clinical manifestations. Bulletin of the Johns Hopkins Hospital 1932;50:137–95.).
There is a class of drugs that is very similar to adrenaline that keeps people in a constant state of alert called amphetamines. Amphetamine use can lead to a break with reality and other schizophrenic symptoms. Could not the constant state of alert of a person who feels threatened do the same? If a person is anxious about a threat they might try and stay awake. They might stay up all night waiting for the intruder or even stay up several nights? Lack of sleep is known to create paranoia. In fact one of the early warning signs of schizophrenia is lack of ability to sleep. One's effort to cope by staying awake could actually feed the paranoia. I know someone who was prescribed antipsychotic medication that he doesn't believe he needs but who takes small doses to help him sleep. It may be that one of the ways antipsychotic medications help schizophrenics is by helping them sleep. It is surprising to me that the medical world has not focussed more on the role of sleep deprivation in contributing to schizophrenia and other forms of mental illness.
The stress hormone in your body that controls when you wake up and when you go to sleep is called cortisol. On effect of lack of sleep is higher cortisol levels. High levels of cortisol in turn cause insomnia so insomnia may involve a self feeding cycle. In an experiment cortisol was infusion has been shown to decrease REM sleep. (Born J, et al. Night-time plasma cortisol secretion is associated with specific sleep stages. Bio Psychiat 1986;21:1415-1424 and Born J, et al. Gluco- and antimineralocorticoid effects on human sleep: a role of central corticosteroid receptors. Amer J Physiol 1991;260(2 Pt 1):E183-E188.)
Cortisol is a hormone that is released during times of significant stress as part of humans' "fight or flight" behaviors. One would expect anyone undergoing paranoia have high levels of cortisol. High levels of cortisol have been shown to be associated with damage to the hippocampus. The hippocampus is a part of the brain which is involved in learning. (Sapolsky R.M., Uno H., Rebert C.S., & Finch C.E. 1990, Hippocampal damage associated with prolonged glucocorticoid exposure in primates. Journal of Neuroscience, 10 (9) 2897-2902). One would expect a paranoid person undergoing sustained stress to have a damaged hippocampus and to have impaired ability to learn or remember.
This has been shown to be the case. According to a report from Stanford University (RU-486 may dramatically relieve psychotic depression, 11/8/2000)
Research over the last 17 years has revealed that cortisol is extremely elevated in psychotically depressed patients. As a "stress" hormone, cortisol is released during times of significant stress as part of humans' "fight or flight" behaviors. In psychotic depression, the natural feedback loop involving cortisol is thought to be awry, with sustained levels of the hormone creating a chronic stress reaction. This in turn may cause the serious symptoms of psychotic depression, including hallucinations, sleep disturbances and memory problems.
It's not necessary for any feedback loop to go awry for cortisol levels to increase, all that's necessary is for the individual to feel stressed. The elevated cortisols resulting from stress can lead to hallucinations and memory problems. The paranoid individual is likely to develop paranoid delusions based on his hallucinations. He may believe his memory loss is occurring because he is being poisoned. (I actually know someone who believes this). The paranoid delusions the stressed individual will develop are likely to feed his paranoia and create a vicious cycle. If the cortisol theory is correct one would expect a drug that lowers cortisol levels to help the paranoid mentally ill. At least some of them have been shown to be helped by RU-486 (see article referenced above) which lowers cortisol levels.
Clearly there are stressed individuals who don't have hallucinations and who don't become paranoid. We should not conclude from that, that stress is not a factor in the development of mental illness but rather that it isn't the whole story.
The self feeding cycle described above is diagrammed below:

Paranoia
Body reacts to anxiety by releasing hormones such as adrenaline and cortisol which together promote a psychotic paranoid response.
Paranoia
Stay awake to defend against threat. Lack of sleep elevates cortisol levels and a self feeding cycle leading to insomnia is created. Lack of sleep also causes paranoia . Defensive fight or flight state creates stress.

Interpret events to confirm one's suspicions.
Paranoia
Desire to protect oneself causes one to cling to paranoid beliefs and refuse medication.
Paranoia

What if one's family becomes alarmed at one's increasing paranoia and takes one to get psychiatric help. The psychiatrist is likely to prescribe medication. One may resist taking such medication because of fear that it will tranquilize oneself so that one doesn't guard one's family. This resisting of medication is a self destructive coping mechanism.
Earlier in this web page I gave the example of someone who thought he saw someone with a knife in the shadows. There is an increased tendency to see something when one expects to see it. As the person in the example becomes more paranoid he is more likely to perceive other men with knives in the shadows which in turn is likely to increase his paranoia still further as well as his conviction that his family is threatened.
What if there really was someone in the shadows and everyone thinks one is crazy but one is right? This has been the idea behind several good scary movies. In fact it is the idea behind an excellent funny/scary movie called the Secret Life of Walter Mitty. The question of how to distinguish reality from fantasy is discussed on the Holding on to Beliefs web page.