Mental health

Incoherence

Incoherence (ICD-11 MB25.03) is a formal thought disorder symptom: speech so disorganized it is incomprehensible to others, seen in psychosis, mania, and delirium, historically termed Wortsalat.

Oct 20, 2026

Increased goal-directed activity

Increased goal-directed activity (ICD-11 MB22.5) is a core mania symptom required with mood change in DSM-5 and ICD-11 criterion A; its addition cut STEP-BD mania/hypomania prevalence by 48% without changing 1-year outcomes.

Increased sociability

Increased sociability (社交性の亢進) is an ICD-11 symptom category, code MB23.C, in which normal social inhibitions are diminished, producing an increased impulse to talk to others and overfamiliarity.

Indecisiveness

Indecisiveness (ICD-11 MB28.6) is the trait-like tendency to have difficulty making decisions or committing to a course of action, measured by the Frost and Shows Indecisiveness Scale and distinct from indecision and procrastination.

Infantile hypotonia-oculomotor anomalies-hyperkinetic movements-developmental delay syndrome

Infantile hypotonia-oculomotor anomalies-hyperkinetic movements-developmental delay syndrome, also called Baker-Gordon syndrome or BAGOS, is a rare autosomal dominant SYT1-related neurodevelopmental disorder with hypotonia, eye anomalies, movement disorders, delay, and EEG abnormality without epilepsy.

Institute of Mental Health (Nottingham, GB)

Institute of Mental Health (IMH), Nottingham: mental health research institute founded 2006, partnership of Nottinghamshire Healthcare NHS Foundation Trust and University of Nottingham; eight centres including MindTech; Director Professor Martin Orrell; Jubilee Campus building opened 2012.

Oct 20, 2026

Insufficient sleep syndrome

Insufficient sleep syndrome (ISS, behaviourally induced hypersomnia, ICD-11 7A26) is a hypersomnolence disorder in which voluntary chronic sleep restriction below individual need causes daily sleepiness, with unimpaired sleep initiation and weekend rebound sleep.

Insulin shock therapy

Insulin shock therapy, or insulin coma therapy, was a psychiatric treatment introduced by Manfred Sakel in Vienna in 1933, inducing hypoglycaemic comas with large insulin doses to treat schizophrenia; abandoned after 1950s randomized trials showed it ineffective.

Intellectual disability-autism-speech apraxia-craniofacial dysmorphism syndrome

Pilarowski-Bjornsson syndrome (PILBOS), also called intellectual disability-autism-speech apraxia-craniofacial dysmorphism syndrome, is a rare autosomal dominant CHD1-related neurodevelopmental disorder with developmental delay, speech apraxia, autism, and mild dysmorphism.

Intellectual disability-expressive aphasia-facial dysmorphism syndrome

Intellectual disability-expressive aphasia-facial dysmorphism syndrome, also called SETBP1 haploinsufficiency disorder, is a rare neurodevelopmental disorder caused by loss of one working copy of the SETBP1 gene.

Intellectual disability-eye abnormalities-microcephaly-peripheral spasticity syndrome

Intellectual disability-eye abnormalities-microcephaly-peripheral spasticity syndrome, also called CTNNB1 syndrome or CTNNB1 neurodevelopmental disorder, is a rare autosomal dominant disorder caused by de novo loss-of-function CTNNB1 variants, featuring intellectual disability, spasticity, microcephaly, and exudative vitreoretinopathy.

Intellectual disability-facial dysmorphism-joint hypermobility-hearing loss syndrome

Intellectual disability-facial dysmorphism-joint hypermobility-hearing loss syndrome, or Beck-Fahrner syndrome (TET3 deficiency, OMIM 618798), is a rare autosomal dominant chromatinopathy causing developmental delay, hypotonia, hearing loss, and overgrowth, diagnosed by TET3 sequencing and a DNA hypermethylation episignature.

Intellectual disability-hypoplastic corpus callosum-preauricular tag syndrome

Intellectual disability-hypoplastic corpus callosum-preauricular tag syndrome, or Da Silva syndrome (ORPHA:1495), is an extremely rare autosomal recessive disorder with severe intellectual disability, microcephaly, corpus callosum hypoplasia, preauricular skin tags, and recurrent bronchopneumonia.

Intellectual disability, Buenos-Aires type

Intellectual disability, Buenos-Aires type, also called Mutchinick syndrome, is a rare autosomal recessive genetic syndrome marked by microcephaly, growth retardation, distinctive facial features, speech disorder, and organ malformations.

Intermittent explosive disorder

Intermittent explosive disorder (IED), a DSM-5 disruptive, impulse-control disorder, features recurrent impulsive aggressive outbursts disproportionate to provocation; US lifetime prevalence 5.4–7.3%, onset in adolescence, treated with CBT and fluoxetine.

Internal Family Systems Model

Internal Family Systems (IFS) is a psychotherapy model by Richard C. Schwartz, from the mid-1980s, treating the mind as parts (exiles, managers, firefighters) led by a core Self; evidence is promising but limited, mainly pilot trials for depression, PTSD, and chronic pain.

Internet addiction disorder

Internet addiction disorder is a proposed, unofficial diagnosis of uncontrolled general internet use, coined satirically in 1995; only gaming disorder is formally recognized (ICD-11), with prevalence estimates from 1–2% to 14% and CBT-based treatment evidence.

Internet-delivered cognitive behavioral therapy

Internet-delivered cognitive behavioral therapy (ICBT) delivers CBT through structured online programs, guided by therapists or self-help, for depression and anxiety; trials show it works as well as face-to-face CBT.

Interpersonal and social rhythm therapy

Interpersonal and social rhythm therapy (IPSRT) is a psychotherapy for bipolar disorder, developed at the University of Pittsburgh by Ellen Frank and colleagues, that stabilizes daily routines.

Interpersonal psychotherapy

Interpersonal psychotherapy (IPT) is a structured, time-limited psychotherapy developed at Yale in the 1970s that treats depression by linking symptoms to grief, role disputes, role transitions, and interpersonal deficits.

Interpersonal theory of suicide

Interpersonal theory of suicide (IPTS), Joiner's 2005 ideation-to-action model: thwarted belongingness plus perceived burdensomeness create desire; acquired capability enables attempts; meta-analytically supported with modest effect sizes.

Interpersonal therapy

Interpersonal therapy (IPT) is a structured, time-limited psychotherapy that treats depression by linking mood symptoms to problems in close relationships, typically over 12 to 16 weekly sessions.

Intrusive thought

Intrusive thought: unwanted, unintended, recurrent thoughts, images, or urges that interrupt thought flow; also called obsessions in OCD. Key concepts include thought-action fusion, suppression rebound effect, and transdiagnostic role in OCD, PTSD, depression.

ITA-VALI-DEM study

ITA-VALI-DEM (NCT06701630) is an observational study by Casa di Cura IGEA, Milan, validating Italian versions of BADL, IADL, E-Cog, NPI-Q, and M-FAQ scales in 390 adults aged 60 and over across SCD, MCI, mild dementia, and unimpaired groups.

Jacques Lacan

Jacques Lacan (1901–1981), French psychiatrist and psychoanalyst, "the French Freud." Known for the mirror stage, the Imaginary-Symbolic-Real registers, the 27-year Seminar, Écrits (1966), and his 1963 IPA expulsion over variable-length sessions.

JAMA Psychiatry

JAMA Psychiatry, formerly Archives of General Psychiatry, is an international peer-reviewed psychiatry journal published by the American Medical Association, renamed in 2013 and edited by Dost Öngür.

James Flynn (academic)

James Robert Flynn (1934-2020), American-born New Zealand moral philosopher and Otago politics professor, documented worldwide generational IQ gains known as the Flynn effect, debated Arthur Jensen on race and IQ, and wrote on philosophy, politics, and free speech.

Jansen-de Vries syndrome

Jansen-de Vries syndrome (JDVS, IDDGIP), a rare autosomal dominant developmental disorder from de novo truncating PPM1D variants on 17q23.2, causing intellectual disability, cyclic vomiting, dysmorphism, and high pain threshold; distinct from Jansen's disease.

Jealous delusion

Jealous delusion, also called morbid jealousy, delusional jealousy, or Othello syndrome, is the fixed belief that one's partner is unfaithful; classified in ICD-11 as MB26.06 and as a DSM-5 delusional disorder subtype.