There are two important characteristics to psychological disorders which can be helpful in understanding a person's condition. They are insight, and control.
The degree to which a person has insight into their condition determines their likelihood of seeking treatment and of achieving some level of recovery.
An alcoholic cannot attempt a cure until they are able to admit their alcoholism. The same applies to all disorders. A treatment applied passively without the sufferer actively engaging and understanding their situation is not likely to work. This is in direct contrast to most medical treatments, which do not require active input. Psychological disorders result from complex behaviour patterns rather than specific biological events. As an example, the use of psychoactive medication such as Prozac for depression only relieves negative symptoms and does not 'cure'. It is up to the user to use some kind of therapy, change of environment etc. and work through the issues that brought about the condition in the first place, otherwise they risk ending up with a Prozac substance abuse disorder.
Different disorders can be associated with different levels of insight.
Depressives are usually able to have good insight into their condition once they have been made aware of it. In fact insight is often a personality characteristic that is part of a vicious cycle contributing to depression's continuation, but also helps lead to eventual recovery.
Schizophrenia, on the other hand, is possibly associated with a lack of insight into personal problems. The root word 'schizo' means 'cut'. Shizophrenics may be described as cut off from themselves in some way or other, showing a lack of continuity, connection, or personal insight. Certainly lack of insight must contribute to the poor prognosis for shizophrenia sufferers.
The abstract concept that we know of as 'insight' probably has a physical manifestation in the brain in the form of a high quantity of neural connections that provide feedback. An individual with a lot of insight is likely to have a more finely etched brain structure than someone without.
Attending counselling sessions with a professional usually helps gain insight into the disorder.
Often a psychological disorder is not detected until the individual loses control and either behaves inappropriately or asks for help. The vast array of psychoactive medications now available are primarily used to enable control over symptoms of disorder, either to suppress pain or discomfort, or to prevent certain behaviour. Medications vary markedly in strength to cater for the different levels of control that psychiatrists wish to exert, which is usually determined as a result of a combination of patient self-reporting and observation of their behaviour. It is possible for a person with great self-control who has intense psychotic experiences to require light or no medication and be given minor labels such as cyclothymic or disthymic even though they can have just as intense experiences as those people labeled psychotic who are on heavy medication.
How much self-control a person has determines the social implications of their condition, the level of medication and the type of labels used. It is easily the most important aspect of any psychological disorder. With high levels of self control, a sufferer can go through their entire life with a major disorder and it is not brought to the attention of the community. High self control is also a positive factor in bringing about successful treatment.