Perhaps due to their perceived rarity, the dissociative disorders (including DID) were not initially included in the Structured Clinical Interview for DSM-IV (SCID), which is designed to make psychiatric diagnoses more rigorous and reliable. Instead, shortly after the publication of the initial SCID a freestanding protocol for dissociative disorders (SCID-D) was published. This interview takes about 30 to 90 minutes depending on the subject's experiences. An alternative diagnostic instrument, the Dissociative Disorders Interview Schedule, also exists but the SCID-D is generally considered superior. The Dissociative Disorders Interview Schedule (DDIS) is a highly structured interview that discriminates among various DSM-IV diagnoses. The DDIS can usually be administered in 30–45 minutes.

Other questionnaires include the Dissociative Experiences Scale (DES), Perceptual Alterations Scale, Questionnaire on Experiences of Dissociation, Dissociation Questionnaire, and the Mini-SCIDD. All are strongly intercorrelated and except the Mini-SCIDD, all incorporate absorption, a normal part of personality involving narrowing or broadening of attention. The DES is a simple, quick, and validated questionnaire that has been widely used to screen for dissociative symptoms, with variations for children and adolescents. Tests such as the DES provide a quick method of screening subjects so that the more time-consuming structured clinical interview can be used in the group with high DES scores. Depending on where the cutoff is set, people who would subsequently be diagnosed can be missed. An early recommended cutoff was 15-20. The reliability of the DES in non-clinical samples has been questioned.

Little is known about prognosis of untreated DID. It rarely, if ever, goes away without treatment, but symptoms may resolve from time to time or wax and wane spontaneously. Patients with mainly dissociative and posttraumatic symptoms face a better prognosis than those with comorbid disorders or those still in contact with abusers, and the latter groups often face lengthier and more difficult treatment. Suicidal ideation, failed suicide attempts, and self-harm also occur. Duration of treatment can vary depending on patient goals, which can extend from elimination of all alters to merely reducing inter-alter amnesia, but generally takes years.

ASPD commonly coexists with the following conditions:

When combined with alcoholism, people may show frontal function deficits on neuropsychological tests greater than those associated with each condition.

According to Professor Emily Simonoff of the Institute of Psychiatry, Psychology and Neuroscience, "childhood hyperactivity and conduct disorder showed equally strong prediction of antisocial personality disorder (ASPD) and criminality in early and mid-adult life. Lower IQ and reading problems were most prominent in their relationships with childhood and adolescent antisocial behaviour."

Treatment by a physician involves assessing parental competence, and whether the parents set limits correctly and consistently. Physicians should rule out dysfunction in the family, referring dysfunctional families for family therapy and dysfunctional parents for parenting skills training, and counsel parents in methods for modifying their child's behavior.

Spoiling in early childhood tends to create characteristic reactions that persist, fixed, into later life. These can cause significant social problems. Spoiled children may have difficulty coping with situations such as teachers scolding them or refusing to grant extensions on homework assignments, playmates refusing to allow them to play with their toys and playmates refusing playdates with them, a loss in friends, failure in employment, and failure with personal relationships. As adults, spoiled children may experience problems with anger management, professionalism, and personal relationships; a link with adult psychopathy has been observed.

A self-disorder, also called ipseity disturbance, is a psychological phenomenon of disruption or diminishing of a person's sense of minimal (or basic) self. The sense of minimal self refers to the very basic sense of having experiences that are one's own; it has no properties, unlike the more extended sense of self, the narrative self, which is characterized by the person's reflections on themselves as a person, things they like, their identity, and other aspects that are the result of reflection on one's self. Disturbances in the sense of minimal self, as measured by the Examination of Anomalous Self-Experience (EASE), aggregate in the schizophrenia spectrum disorders, to include schizotypal personality disorder, and distinguish them from other conditions such as psychotic bipolar disorder and borderline personality disorder.

Studies suggest that the prevalence of paraphrenia in the elderly population is around 2-4%.

While paraphrenia can occur in both men and women, it is more common in women, even after the difference has been adjusted for life expectancies. The ratio of women with paraphrenia to men with paraphrenia is anywhere from 3:1 to 45:2

The minimal self has been likened to a "flame that enlightens its surroundings and thereby itself." Unlike the extended self, which is composed of properties such as the person's identity, the person's narrative, and other aspects that can be gleaned from reflection, the minimal self has no properties, but refers to the "mine-ness" "given-ness" of experience, that the experiences are that of the person having them in that person's stream of consciousness. These experiences that are part of the minimal self are normally "tacit" and implied, requiring no reflection on the part of the person experiencing to know that the experience is theirs. The minimal self cannot be further elaborated and normally one cannot grasp it upon reflection. The minimal self goes hand-in-hand with immersion in the shared social world, such that "[t]he world is always pregiven, ie, tacitly grasped as a self-evident background of all experiencing and meaning." This is the self-world structure.

De Warren gives an example of the minimal self combined with immersion in the shared social world: "When looking at this tree in my backyard, my consciousness is directed toward the tree and not toward my own act of perception. I am, however, aware of myself as perceiving this tree, yet this self-awareness (or self-consciousness) is not itself thematic." The focus is normally on the tree itself, not on the person's own act of seeing the tree: to know that one is seeing the tree does not require an act of reflection.

Cannabis use disorder is recognized in the fifth version of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-5), which added cannabis withdrawal as a new condition. In the United States, the average adult who seeks treatment has consumed cannabis for over 10 years almost daily and has actively attempted to quit six or more times.

Young people are at greater risk of developing cannabis dependency because of the association between early initiation into substance use and subsequent problems such as dependence, and the risks associated with using cannabis at a developmentally vulnerable age. In addition there is evidence that cannabis use during adolescence, at a time when the brain is still developing, may have deleterious effects on neural development and later cognitive functioning.

Some patients have been treated by injecting botulinum toxin (botox) near the vocal cords. This does not prevent the vocalizations, but the partial paralysis that results helps to control the volume of any outbursts. Surprisingly, botox injections result in more generalized relief of tics than the vocal relief expected.

The severity and frequency of outbursts can also be decreased by surgically disabling nuclei in the thalamus, the globus pallidus and the cingulate cortex.

Risk factors (constructs which increase the likelihood or intensity of homesickness) and protective factors (constructs that decrease the likelihood or intensity of homesickness) vary by population. For example, a seafarers on board, the environmental stressors associated with a hospital, a military boot camp or a foreign country may exacerbate homesickness and complicate treatment. Generally speaking, however, risk and protective factors transcend age and environment.

Factors which mitigate the prevalence or intensity of homesickness are essentially the inverse of the risk factors cited above. Effective coping (reviewed in the following section) also diminishes the intensity of homesickness over time. Prior to a separation, however, key protective factors can be identified. Positive adjustment to separation from home is generally associated with the following factors:

- Experience factors: Older age; substantial previous experience away from home (for which age can be a proxy); previous experience in the novel environment; previous experience venturing out without primary caregivers.

- Attitude factors: The belief that homesickness will be mild; positive first impressions and high expectations for the new environment; perceptions of social support; low perceived demands (e.g., on academic or vocational performance); short perceived distance from home

- Personality factors: Secure attachment relationship with primary caregivers; high perceived control over the timing and nature of the separation from home; good mental health in the months prior to the separation; high self-directedness; adventure-seeking; flexibility; an instrumental coping style.

- Family factors: High decision control (e.g., caregivers including a young person in the decision to spend time away from home); individuals making their own choice about military service; supportive caregiving; caregivers who express confidence and optimism about the separation (e.g., "Have a great time away. I know you'll do great.")

- Environmental factors: Low cultural contrast (e.g., same language, similar customs, familiar food in the new environment); physical and emotional safety; few changes to familiar daily schedule; plenty of information about the new place prior to relocation; feeling welcome and accepted in the new place.

Attention-Deficit Hyperactivity Disorder (ADHD)[33][34]

Obsessive-Compulsive Disorder (OCD)[33][34]

Anxiety [33][34]

Lower Quality of Life [33][34]

Depression [33][34]

Aggression [34]

Emotional Dysregulation [34]

Physical consequences such as pain and discomfort of the repetitive movements [33]

Low Self-Esteem [33]

Autism Spectrum Disorder [33]

The condition has been recognized since the mid- to late-1950s.

Research into the genetics of LFS has been conducted at the University of California, Davis and Cornell University in the United States, the University of Queensland in Australia, and the University of Pretoria in South Africa. In November, 2009, Cornell University announced a DNA test has been developed to detect carriers of LFS. Simultaneously, the University of Pretoria also announced they had developed a DNA test. Testing is now available at Cornell, Pretoria, and Queensland, Australia.

Lavender foal syndrome (LFS), also called coat color dilution lethal (CCDL), is an autosomal recessive genetic disease that affects newborn foals of certain Arabian horse bloodlines. Affected LFS foals have severe neurological abnormalities, cannot stand, and require euthanasia shortly after birth. The popular name originates due to a diluted color of the foals coat, that in some cases appears to have a purple or lavender hue. However, not all foals possess the lavender coat colour, colouring can range from silver to light chestnut to a pale pink. Carrier horses have no clinical signs and DNA testing can determine if a horse carries the gene.