Dimensional models
The high degree of comorbidity between disorders in categorical models such as the DSM and ICD have led some to propose dimensional models. Studying comorbidity between disorders have demonstrated two latent (unobserved) factors or dimensions in the structure of mental disorders that are thought to possibly reflect etiological processes. These two dimensions reflect a distinction between internalizing disorders, such as mood or anxiety symptoms, and externalizing disorders such as behavioral or substance use symptoms. A single general factor of psychopathology, similar to the g factor for intelligence, has been empirically supported. The p factor model supports the internalizing-externalizing distinction, but also supports the formation of a third dimension of thought disorders such as schizophrenia. Biological evidence also supports the validity of the internalizing-externalizing structure of mental disorders, with twin and adoption studies supporting heritable factors for externalizing and internalizing disorders. A leading dimensional model is the Hierarchical Taxonomy of Psychopathology. Disorders
There are many different categories of mental disorder, and many different facets of human behavior and personality that can become disordered. Anxiety disorder
An anxiety disorder is anxiety or fear that interferes with normal functioning may be classified as an anxiety disorder. Commonly recognized categories include specific phobias, generalized anxiety disorder, social anxiety disorder, panic disorder, agoraphobia, obsessive-compulsive disorder and post-traumatic stress disorder. Mood disorder
Other affective (emotion/mood) processes can also become disordered. Mood disorder involving unusually intense and sustained sadness, melancholia, or despair is known as major depression (also known as unipolar or clinical depression). Milder, but still prolonged depression, can be diagnosed as dysthymia.
Disorders like depression, anxiety and schizophrenia, personality disorder, old age-related disorder, substance abuse disorder are common in Nigeria, as in other countries in Africa.Nigeria is still nowhere near being equipped to solve prevailing mental health challenges. With little scientific research been carried out, coupled with insufficient mental health hospitals in the country, traditional healers provide specialised psychotherapy care to those that require their services.and pharmacotherapy

Society and culture
Different societies or cultures, even different individuals in a subculture, can disagree as to what constitutes optimal versus pathological biological and psychological functioning. Research has demonstrated that cultures vary in the relative importance placed on, for example, happiness, autonomy, or social relationships for pleasure. Likewise, the fact that a behavior pattern is valued, accepted, encouraged, or even statistically normative in a culture does not necessarily mean that it is conducive to optimal psychological functioning. People in all cultures find some behaviors bizarre or even incomprehensible. But just what they feel is bizarre or incomprehensible is ambiguous and subjective. These differences in determination can become highly contentious. The process by which conditions and difficulties come to be defined and treated as medical conditions and problems, and thus come under the authority of doctors and other health professionals, is known as medicalization or pathologization. Mental illness in the Latin American community
There is a perception in Latin American communities, especially among older people, that discussing problems with mental health can create embarrassment and shame for the family.