The definition and classification of mental disorders are key issues for researchers as well as service providers and the individuals who may be diagnosed. For a mental state to classify as a disorder, it generally needs to cause dysfunction. According to DSM-IV, a mental disorder is a psychological disorder or pattern which is associated with distress disability impairment in at least one important areas of functioning, increased risk of death, or causes a significant loss of autonomy; anyway it bars normal responses, for example, sadness from loss of a friend or family member, and also avoids deviant behavior for political, religious, or societal reasons not arising from a dysfunction in the individual.
The expressions "mental breakdown" or "mental meltdown" may be used by the general population to mean a mental disorder. The expressions "mental meltdown" and "mental breakdown" have not been formally defined through a medical diagnostic framework, for example, the DSM-5 or ICD-10, and are nearly absent from logical literature regarding mental illness. In 2013, the American Psychiatric Association redefined mental disorders in the DSM-5 as "a disorder characterized by clinically significant disturbance in an individual's cognition, emotion regulation, or behavior that mirrors a dysfunction in the psychological, biological, or developmental procedures underlying mental functioning."
The final draft of ICD-11 contains a fundamentally the same as definition. Although "mental meltdown" is not thoroughly defined, reviews of laypersons recommend that the term alludes to a particular acute time-constrained reactive disorder, involving side effects, for example, anxiety or depression, usually precipitated by external stressors. Many health specialists today allude to a mental meltdown as a "mental health crisis". DSM-IV goes before the definition with caveats, stating that, as in the case with many medical terms, mental disorder "lacks a consistent operational definition that covers all situations", noting that various dimensions of abstraction can be used for medical definitions, including pathology, symptomology, deviance from a normal range, or etiology, and that the same is valid for mental disorders, so now and then one sort of definition is appropriate, and at times another, depending on the situation.