ADHD-PI is an attention-concentration deficit that has everything in common with other forms of ADHD except that it has fewer hyperactivity or impulsivity symptoms and has more directed attention fatigue symptoms.

Different countries have used different ways of diagnosing ADHD-PI. In the United Kingdom, diagnosis is based on quite a narrow set of symptoms, and about 0.5–1% of children are thought to have attention or hyperactivity problems.

The DSM-5 allows for diagnosis of the "predominantly inattentive" presentations of ADHD (code 314.00) if the individual presents six or more (five for adults) of the following symptoms of inattention for at least six months to a point that is disruptive and inappropriate for developmental level:

- Often does not give close attention to details or makes careless mistakes in schoolwork, work, or other activities.

- Often has trouble keeping attention on tasks or play activities.

- Often does not seem to listen when spoken to directly.

- Often does not follow instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions).

- Often has trouble organizing activities.

- Often avoids, dislikes, or doesn't want to do things that take a lot of mental effort for a long period (such as schoolwork or homework).

- Often loses things needed for tasks and activities (e.g. toys, school assignments, pencils, books, or tools).

- Is often easily distracted.

- Is often forgetful in daily activities.

An ADHD diagnosis is contingent upon the symptoms of impairment presenting themselves in two or more settings (e.g., at school or work and at home). There must also be clear evidence of clinically significant impairment in social, academic, or occupational functioning. Lastly, the symptoms must not occur exclusively during the course of a pervasive developmental disorder, schizophrenia, or other psychotic disorder, and are not better accounted for by another mental disorder (e.g., mood disorder, anxiety disorder, dissociative disorder, personality disorder).

Additionally, requirements for a proposed diagnosis such as the number and duration of symptoms and the impact on functioning are continuing to be investigated. But there is no doubt that both ADHD and SCT are found in children and adults and are linked to significant impairment and a diminished quality of life (QoL). The research by Barkley suggests that this is especially true if ADHD and SCT occur together: In adults, those comorbid cases were more likely to be unmarried and to be out of work on disability compared to cases with ADHD alone. But SCT alone is also present in the population and can be quite impairing in educational and occupational settings, even if it is not as pervasively impairing as ADHD.

ADHD is the only disorder of attention currently defined by the DSM-5 or ICD-10. Formal diagnosis is made by a qualified professional, and includes demonstrating six or more symptoms of inattention, hyperactivity and impulsivity, or both. This results in three types of ADHD:

- a predominantly inattentive presentation (ADHD-I)

- a predominantly hyperactive-impulsive presentation (ADHD-HI)

- a combined presentation (ADHD-C)

The symptoms must also be inappropriate and must interfere with social, school, or work functioning, in addition to meeting multiple other diagnostic requirements. The symptoms used in the diagnosis are shown below.

SCT is proposed to be a similar disorder to the predominantly inattentive presentation (ADHD-I), but, as discussed later, importantly distinct from it. One problem is that some individuals who actually have SCT are now mistakenly diagnosed with the inattentive presentation. The list of symptoms that follows is from leading researchers of SCT, however, no universally accepted set of symptoms has been developed since this symptom cluster has not yet been recognized as an independent disorder.

Bipolar I disorder (BD-I; pronounced "type one bipolar disorder") is a bipolar spectrum disorder characterized by the occurrence of at least one manic or mixed episode. Most patients also, at other times, have one or more depressive episodes, and all experience a hypomanic stage before progressing to full mania.

It is a type of bipolar disorder, and conforms to the classic concept of manic-depressive illness, which can include psychosis during mood episodes. The difference with bipolar II disorder is that the latter requires that the individual must never have experienced a full manic or mixed-manic episode - only less severe hypomanic episode(s).

The essential feature of bipolar I disorder is a clinical course characterized by the occurrence of one or more manic episodes or mixed episodes (DSM-IV-TR, 2000). Often, individuals have had one or more major depressive episodes. One episode of mania is sufficient to make the diagnosis of bipolar disorder; the patient may or may not have history of major depressive disorder. Episodes of substance-induced mood disorder due to the direct effects of a medication, or other somatic treatments for depression, drug abuse, or toxin exposure, or of mood disorder due to a general medical condition need to be excluded before a diagnosis of bipolar I disorder can be made. In addition, the episodes must not be better accounted for by schizoaffective disorder or superimposed on schizophrenia, schizophreniform disorder, delusional disorder, or a psychotic disorder not otherwise specified.

People with hypersexual disorder experience multiple, unsuccessful attempts to control or diminish the amount of time spent engaging in sexual fantasies, urges, and behaviors in response to dysphoric mood states or stressful life events.

For a valid diagnosis of hypersexual disorder to be established, symptoms must persist for a period of at least 6 months and occur independently of a use mania or a medical condition.

Hypersexual disorder is a pattern of behavior involving intense preoccupation with sexual fantasies, urges and activities, leading to adverse consequences and clinically significant distress or impairment in social, occupational or other important functions. It was proposed in 2010 for inclusion in the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) of the American Psychiatric Association (APA).

According to Michael First of the DSM-5 working committee the focus of a relational disorder, in contrast to other DSM-IV disorders, "is on the relationship rather than on any one individual in the relationship".

Relational disorders involve two or more individuals and a disordered "juncture", whereas typical Axis I psychopathology describes a disorder at the individual level. An additional criterion for a relational disorder is that the disorder cannot be due solely to a problem in one member of the relationship, but requires pathological interaction from each of the individuals involved in the relationship.

For example, if a parent is withdrawn from one child but not another, the could be attributed to a relational disorder. In contrast, if a parent is withdrawn from both children, the dysfunction may be more appropriately attributable to a disorder at the individual level.

First states that "relational disorders share many elements in common with other disorders: there are distinctive features for classification; they can cause clinically significant impairment; there are recognizable clinical courses and patterns of comorbidity; they respond to specific treatments; and they can be prevented with early interventions. Specific tasks in a proposed research agenda: develop assessment modules; determine the clinical utility of relational disorders; determine the role of relational disorders in the etiology and maintenance of individual disorders; and consider aspects of relational disorders that might be modulated by individual disorders."

The proposed new diagnosis defines a relational disorder as "persistent and painful patterns of feelings, behaviors, and perceptions" among two or more people in an important personal relationship, such a husband and wife, or a parent and children.

According to psychiatrist Darrel Regier, MD, some psychiatrists and other therapists involved in couples and marital counseling have recommended that the new diagnosis be considered for possible incorporation into the Diagnostic and Statistical Manual of Mental Disorders (DSM IV).

Cognitive symptoms from steroids appear within the first few weeks of treatment, appear to be dose dependent, and may or may not be accompanied by steroid psychosis or other Cushing's-type symptoms.

The symptoms include deficits in

- verbal and non-verbal memory

- working memory

- attention

- sustained concentration

- executive function

- psychomotor speed

- academic or occupational performance.

These symptoms have been shown to improve within months to a year after discontinuing glucocorticoid medication, but residual impairments following prolonged steroid use can remain.

Hypersexuality is a clinical diagnosis used by mental healthcare professionals to describe extremely frequent or suddenly increased libido. The terms nymphomania and satyriasis were once used to describe the condition, in women and men respectively, but are no longer in general medical use, although the former is still used colloquially.

Hypersexuality may be a primary condition, or the symptom of another medical disease or condition, for example Klüver-Bucy syndrome or bipolar disorder. Hypersexuality may also present as a side effect of medication such as drugs used to treat Parkinson's disease, or through the administering of hormones such as testosterone and estrogen during hormone therapy.

Clinicians have yet to reach a consensus over how best to describe hypersexuality as a primary condition, or to determine the appropriateness of describing such behaviors and impulses as a separate pathology.

Hypersexual behaviours are viewed variously by clinicians and therapists as an addiction, a type of obsessive-compulsive disorder (OCD) or “OCD-spectrum disorder", or a disorder of impulsivity. A number of authors do not acknowledge such a pathology and instead assert that the condition merely reflects a cultural dislike of exceptional sexual behavior.

Consistent with there not being any consensus over what causes hypersexuality, authors have used many different labels to refer to it, sometimes interchangeably, but often depending on which theory they favor or which specific behavior they were studying. Contemporary names include compulsive masturbation, compulsive sexual behavior, cybersex addiction, erotomania, “excessive sexual drive”, hyperphilia, hypersexuality, hypersexual disorder, problematic hypersexuality, sexual addiction, sexual compulsivity, sexual dependency, sexual impulsivity, “out of control sexual behavior”, and paraphilia-related disorder.

Circumstantial speech (also referred to as circumstantiality) is the result of a so called "non-linear thought pattern" and occurs when the focus of a conversation drifts, but often comes back to the point. In circumstantiality, apparently unnecessary details and seemingly irrelevant remarks cause a delay in getting to the point.

If someone exhibits circumstantial speech during a conversation, they will often seem to "talk the long way around" to their point, which may be an attempt by the speaker to include pertinent hyperspatial details, that may contrast with linear speech, which is more direct, succinct, and to the point (the gist) even at the expense of more precise, accurate communication. Some individuals with autistic tendencies may prefer highly precise speech, and this may seem circumstantial, but in fact it is a choice that posits that more details are necessary to communicate a precise meaning, and preempt more disastrous ambiguous communication.

Circumstantial speech is more direct than tangential speech in which the speaker wanders and drifts (in order to add more thought vectors in unrelated hyperplanes) and usually never returns to the original topic, and is far less severe than logorrhea. A helpful metaphor is traveling to a destination. If someone is thinking and speaking linearly, then they will go directly to the point. Circumstantial speech is more like taking "unnecessary" detours, according to some, but the speaker eventually arrives at the intended destination. In tangential speech, the speaker simply gets lost along the way, never returning to the original topic of conversation. With logorrhea, which is closer to word salad, it may not even be clear that the speaker had a particular idea or point in the first place.

Steroid dementia syndrome describes the signs and symptoms of hippocampal and prefrontal cortical dysfunction, such as deficits in memory, attention, and executive function, induced by glucocorticoids. Dementia-like symptoms have been found in some individuals who have been exposed to glucocorticoid medication, often dispensed in the form of asthma, arthritis, and anti-inflammatory steroid medications. The condition reverses, but not always completely, within months after steroid treatment is stopped.

The term "steroid dementia" was coined by Varney et al. (1984) in reference to the effects of long-term glucocorticoid use in 1,500 patients. While the condition generally falls under the classification of Cushing's syndrome, the term "steroid dementia syndrome" is particularly useful because it recognizes both the cause of the syndrome and the specific effects of glucocorticoids on cognitive function. Further, the more precise terminology clearly distinguishes the condition from full-blown Cushing's syndrome, which is extremely broad regarding the causes (endogenous or exogenous, pituitary or adrenal) and the multitude of symptoms (ranging from skin disorders to osteoporosis), and from hypercortisolemia, which identifies neither the source nor the symptoms of excess circulatory cortisol.

A person afflicted with circumstantiality has slowed thinking and invariably talks at length about irrelevant and trivial details (i.e. circumstances). Eliciting information from such a person can be difficult since circumstantiality makes it hard for the individual to stay on topic. In most instances however, the relevant details are eventually achieved.

The disorder is often associated with schizophrenia and obsessive-compulsive disorder.

Treatment-resistant depression (TRD) or treatment-refractory depression is a term used in clinical psychiatry to describe cases of major depressive disorder (MDD) that do not respond adequately to appropriate courses of at least two antidepressants. The term was first coined with the development of the concept in 1974. Inadequate response has traditionally been defined as no response whatsoever. However, many clinicians consider a response inadequate if the patient does not achieve full remission of symptoms. Cases of treatment-resistant depression in which the course of treatment was not adequate are sometimes referred to as pseudoresistant. Some factors that contribute to inadequate treatment are: early discontinuation of treatment, insufficient dosage of medication, patient noncompliance, misdiagnosis, and concurrent psychiatric disorders. Cases of treatment-resistant depression may also be referred to by which medications they are resistant to (i.e.: SSRI-resistant).

Comorbid psychiatric disorders commonly go undetected in the treatment of depression. If left untreated, the symptoms of these disorders can interfere with both evaluation and treatment.

Anxiety disorders are one of the most common disorder types associated with treatment-resistant depression. The two disorders commonly co-exist, and have some similar symptoms. Some studies have shown that patients with both MDD and panic disorder are the most likely to be nonresponsive to treatment.

Substance abuse may also be a predictor of treatment-resistant depression. It may cause depressed patients to be noncompliant in their treatment, and the effects of certain substances can worsen the effects of depression.

Other psychiatric disorders that may predict treatment-resistant depression include personality disorders, obsessive compulsive disorder, and eating disorders.

Hypersexuality is known to present itself as a symptom in connection to a number of mental and neurological disorders. Some people with borderline personality disorder (sometimes referred to as BPD) can be markedly impulsive, seductive, and extremely sexual. Sexual promiscuity, sexual obsessions, and hypersexuality are very common symptoms for both men and women with BPD. On occasion for some there can be extreme forms of paraphilic drives and desires. "Borderline" patients, due in the opinion of some to the use of splitting, experience love and sexuality in unstable ways.

People with bipolar disorder may often display tremendous swings in sex drive depending on their mood. As defined in the DSM-IV-TR, hypersexuality can be a symptom of hypomania or mania in bipolar disorder or schizoaffective disorder. Pick's disease causes damage to the temporal/frontal lobe of the brain; people with Pick's disease show a range of socially inappropriate behaviors.

Several neurological conditions such as Alzheimer's disease, autism, various types of brain injury, Klüver–Bucy syndrome, Kleine–Levin syndrome, and many more neurodegenerative diseases can cause hypersexual behavior. Sexually inappropriate behavior has been shown to occur in 7-8% of Alzheimer's patients living at home, at a care facility or in a hospital setting. Hypersexuality has also been reported to result as a side-effect of some medications used to treat Parkinson's disease. Some street drugs, such as methamphetamine, may also contribute to hypersexual behavior.

A positive link between the severity of dementia and occurrence of inappropriate behavior has also been found. Hypersexuality can be caused by dementia in a number of ways, including disinhibition due to organic disease, misreading of social cues, understimulation, the persistence of learned sexual behaviour after other behaviours have been lost, and the side-effects of the drugs used to treat dementia. Other possible causes of dementia-related hypersexuality include an inappropriately expressed psychological need for intimacy and forgetfulness of the recent past. As this illness progresses, increasing hypersexuality has been theorized to sometimes compensate for declining self-esteem and cognitive function.

Facial features of children with Smith–Magenis syndrome include a broad face, deep-set eyes, large cheeks, and a prominent jaw, as well as a flat nose bridge. The mouth curves downwards and the upper lip curves outwards. These facial features become more noticeable as the individual ages.

Disrupted sleep patterns are characteristic of Smith–Magenis syndrome, typically beginning early in life. Affected people may be very sleepy during the day, but have trouble falling asleep and awaken several times each night, due to an inverted circadian rhythm of melatonin.

People with Smith–Magenis syndrome have engaging personalities, but all also have a lot of behavioral problems. These behavioral problems include frequent temper tantrums, meltdowns and outbursts, aggression, anger, fidgeting, compulsive behavior, anxiety, impulsiveness, and difficulty paying attention. Self-harm, including biting, hitting, head banging, and skin picking, is very common. Repetitive self-hugging is a behavioral trait that may be unique to Smith–Magenis syndrome. People with this condition may also compulsively lick their fingers and flip pages of books and magazines (a behavior known as "lick and flip"), as well as possessing an impressive ability to recall a wide range of small details about people or subject-specific trivia.

Other symptoms can include short stature, abnormal curvature of the spine (scoliosis), reduced sensitivity to pain and temperature, and a hoarse voice. Some people with this disorder have ear abnormalities that lead to hearing loss. Affected individuals may have eye abnormalities that cause nearsightedness (myopia), strabismus, and other problems with vision. Heart and kidney defects also have been reported in people with Smith–Magenis syndrome, though they are less common.

Smith–Magenis Syndrome (SMS) is a genetic disorder with features including intellectual disability, facial abnormalities, difficulty sleeping, and numerous behavioral problems such as self-harm. Smith–Magenis syndrome affects an estimated between 1 in 15,000 to 1 in 25,000 individuals.

It is a microdeletion syndrome characterized by an abnormality in the short (p) arm of chromosome 17 and is sometimes called the 17p- syndrome.

Research on parent–child abuse bears similarities to that on marital violence, with the defining characteristic of the disorder being physical aggression by a parent toward a child. The disorder is frequently concealed by parent and child, but may come to the attention of the clinician in several ways, from emergency room medical staff to reports from child protection services.

Some features of abusive parent–child relationships that serve as a starting point for classification include: (a) the parent is physically aggressive with a child, often producing physical injury, (b) parent–child interaction is coercive, and parents are quick to react to provocations with aggressive responses, and children often reciprocate aggression, (c) parents do not respond effectively to positive or prosocial behavior in the child, (d) parents do not engage in discussion about emotions, (e) parent engages in deficient play behavior, ignores the child, rarely initiates play, and does little teaching, (f) children are insecurely attached and, where mothers have a history of physical abuse, show distinctive patterns of disorganized attachment, and (g) parents relationship shows coercive marital interaction patterns.

Defining the relational aspects of these disorders can have important consequences. For example, in the case of early appearing feeding disorders, attention to relational problems may help delineate different types of clinical problems within an otherwise broad category. In the case of conduct disorder, the relational problems may be so central to the maintenance, if not the etiology, of the disorder that effective treatment may be impossible without recognizing and delineating it.

The oculogyric crises usually occur in the later half of the day and during these episodes patients undergo extreme agitation and irritability along with uncontrolled head and neck movements. Apart from the aforementioned symptoms, patients can also display Parkinsonism, sleep disturbances, small head size (microcephaly), behavioral abnormalities, weakness, drooling, and gastrointestinal symptoms.

Sepiapterin reductase deficiency is an inherited pediatric disorder characterized by movement problems, and most commonly displayed as a pattern of involuntary sustained muscle contractions known as dystonia. Symptoms are usually present within the first year of age, but diagnosis is delayed due to physicians lack of awareness and the specialized diagnostic procedures. Individuals with this disorder also have delayed motor skills development including sitting, crawling, and need assistance when walking. Additional symptoms of this disorder include intellectual disability, excessive sleeping, mood swings, and an abnormally small head size. SR deficiency is a very rare condition. The first case was diagnosed in 2001, and since then there have been approximately 30 reported cases. At this time, the condition seems to be treatable, but due to a lack of overall awareness and a series of atypical procedures used to diagnose this condition pose a dilemma.

Cross-tolerance is a phenomenon that occurs when tolerance to the effects of a certain drug produces tolerance to another drug. It often happens between two drugs with similar functions or effects – for example, acting on the same cell receptor or affecting the transmission of certain neurotransmitters. Cross-tolerance has been observed with pharmaceutical drugs such as anti-anxiety agents and illicit substances, and sometimes the two of them together. Often, a person who uses one drug can be tolerant to a drug that has a completely different function. This phenomenon allows one to become tolerant to a drug that they have never even used before.

Adipsia, also known as hypodipsia, is a symptom of inappropriately decreased or absent feelings of thirst. It involves an increased osmolality or concentration of solute in the urine, which stimulates secretion of antidiuretic hormone (ADH) from the hypothalamus to the kidneys. This causes the person to retain water and ultimately become unable to feel thirst. Due to its rarity, the disorder has not been the subject of many research studies.

Adipsia may be seen in conditions such as diabetes insipidus and may result in hypernatremia. It can occur as the result of abnormalities in the hypothalamus, pituitary and corpus callosum, as well as following pituitary/hypothalamic surgery.

It is possible for hypothalamic dysfunction, which may result in adipsia, to be present without physical lesions in the hypothalamus, although there are only four reported cases of this. There are also some cases of patients experiencing adipsia due to a psychiatric disease. In these rare psychogenic cases, the patients have normal levels of urine osmolality as well as typical ADH activity.

ISWD has various causes, including neurological disorders such as dementia (particularly Alzheimer's Disease), brain damage, or mental retardation. It is thought that sufferers have a weak circadian clock. The risk for the disorder increases with age, but only due to increased prevalence of co-morbid medical disorders.