The term psychosis is used to refer to a syndrome composed of the following -- disturbances of sleep, disturbances of attention, thought disturbance, and often, neuromotor findings.
It has a high level of similarity to delirium. Delirium is believed to be caused by CNS metabolism illness, which in turn, is typically attributed to systemic illness.
For example, the most common cause of derlium, in our society, is cardiac disease. When cardiac disease occurs, a wide range of metabolic disturbances occur. Electrolyte impalances can occur. endocrine disturbances (in secretion of peptides such as vasopressin) occur. Anoxic injury can occur, leading to a wide range of losses of physiologic functions. cumulatively, when these have an impact on the CNS, the end point injury is to the cogntiive process that allows attention to dates, times, time of day, other features of diurnal cycle, and awareness of physical surroundings.
At one pioint in the past, physicians would refer to this cumulative loss as "disturbance of sensorium".
The only long term treatment for delirium is treatment of the underlying illness. However, one often finds a physician's consult report asking that treatments with neuroleptics be used. Why is this ?
Because neuroleptics act on CNS circuitry, and are believed to be beneficial to controlling those aspects of delirium that impair a patient's capacity to make decisions and carry them out.
The question, using the analogy of delirium is, then, what is the derrangement or acute ilness present in psychosis ?
We can construct a picture of psychosis by being able to identify, first, what it is. We will argue here that it is a neurophysiologic process that occurs or worsens when underlying conditions, and in some cases, illnesses are present.
A good example of this is alcohol withdrawal, coupled with a cumulative alcohol toxicity, nutritional depletion, acute alchol toxicity, and sleep deprivation. There are many illness processes occruing, but they often seem to converge into a single phenomena, psychosis, albeit a psychosis specific to this case. Some cases are called delirium tremens, but we often save this for labelling just the case of a specific type of prolonged withdrawal.
This helps clarify that psychosis, rather than an overwhelming illness, is a very specific derrangement ofthe CNS that is seen in many different illnesses. The coexistence of co morbid processes needs to be identified as distinct from the psychoosis itself. In the case of DTs, seizures may coexist and yet, are distinct in terms of a neurologic process.
The predisposing condition for psychosis, and often the first step, is a derrangement of the processing of sensory information -- often in several domains. The typicl domains of sensory process disturbances include simple auditory processing, a wide range of higher level auditory processing, vibrational tactile information, and spatial data as assembled by snesory processing of vibrational tacile information.
Of course, these disturbances proceed from a range of causes.
The next step in psychosis is usually a cmpensatory one -- an attempt by the reasoning mend, to expalin the disturbed information prosented by the sensory processing. As a consequence, a range of subsequent typical occurences in psychosis result: paranoia, paranoid delusions, paranoid repsonses, and suspiciousness.
The next phase, an acute phase, represents the stage that is most dangerous, difficulty with contact with reality, and an erosion of the ablity to think linearly.