The definition of mental illnesses is a complex and controversial subject, where there is no universal consensus yet. The disagreements are not only at the level of different perspectives such as psychoanalytical, medical, socio-cultural, etc, but are evident within them as well. Since mental illnesses don’t lend themselves to physiologic proofs such as blood tests or scans, the psychiatrist/psychologist has to resort to evaluation methods such as questionnaires, personal interviews and other indirect methods of arriving at an inference. The drawback with such methods is that they are not precise and subject to interpretation and presentation, which can compound errors. Moreover, there is no consensus when it comes to definition of several major mental illnesses. Definitions of normality and abnormality in mental health have proven to be abstract, inconclusive and have elicited contestation. Take say, the example of Adjustment disorder, which occupies a peculiar position in the diagnostic system of the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; American Psychiatric Association, 2000). The manual shows Adjustment disorder as “straddling the boundary between normal and abnormal psychology”. (Daniels, 2009) In contrast, a more human-centered approach in counseling (as espoused by the humanist framework) “offers a defense of “normal” adjustment as demonstrating human adaptation in life. This means there are deeper philosophical and clinical implications of this position”. (Daniels, 2009)
Psychological illness being a somewhat contested concept has led to ambiguity in interpretation and drawing of definitions. On the one hand, “the normal may be thought of simply as the typical or common. On the other hand, it is sometimes intended normatively or evaluatively”. (Dupre, 1998) The interplay between these usages is captured in the dictionary. For example, one dictionary has the following list of explanations for the word ‘normal’: “1. conforming to the standard or the common type; usual; regular; natural; 2. serving to fix a standard; 3. of natural occurrence; 4. approximately average in any psychological trait, as intelligence, personality, or emotional adjustment; 5. free from any mental disorder; sane; 6. free from disease or malformation.” (Dupre, 1998) The ambiguity in the general understanding of ‘normal’ is only more pronounced across different analytic frameworks such as cognitive, behavioral, humanistic, socio-cultural, etc.
Some of the major psychological disorders currently include Anxiety, Phobia, Panic Disorder, Depression, Schizophrenia, Personality Disturbances, Psycho-Somatic illnesses, etc. In most cases, an individual diagnosed with any of these disorders also carries symptoms of other related disorders. For example, those who suffer from Major Depression are also likely to carry symptoms of anxiety and panic to varying degrees. Similarly, those suffering from Schizophrenia are prone to have personality disturbances. In this way, there is continuity and overlap among commonly labeled psychological illnesses.