Major Neurocognitive Disorder

Major Neurocognitive Disorder (NCD), the DSM-5-TR term for what was previously called dementia, refers to significant cognitive decline from a prior level of performance in one or more cognitive domains — complex attention, executive function, learning and memory, language, perceptual-motor function, or social cognition. The decline must interfere with independence in everyday activities. DSM-5-TR distinguishes Major NCD (formerly dementia) from Mild NCD (previously mild cognitive impairment). References: DSM-5-TR, StatPearls (NCBI Bookshelf).

Major Neurocognitive Disorder (NCD), the DSM-5-TR term for what was previously called dementia, refers to significant cognitive decline from a prior level of performance in one or more cognitive domains — complex attention, executive function, learning and memory, language, perceptual-motor function, or social cognition. The decline must interfere with independence in everyday activities. DSM-5-TR distinguishes Major NCD (formerly dementia) from Mild NCD (previously mild cognitive impairment). The most common aetiological subtypes are Alzheimer's disease (~60-70%), vascular disease (~15-20%), Lewy body disease (~5-10%), and frontotemporal lobar degeneration (~5%). Mixed pathology — most commonly Alzheimer's plus cerebrovascular disease — accounts for 20-30% of autopsy-confirmed cases. Approximately 55 million people live with dementia worldwide (WHO, 2023), with ~10 million new cases annually. It carries ICD-11 code 6D80. Dementia is the 7th leading cause of death globally and a major driver of disability and dependence in older adults. This information is for psychoeducation only.

Symptoms depend on the subtype and affected cognitive domains. Alzheimer's type: insidious onset with gradual progression. Early: episodic memory loss (repeating questions, misplacing items, forgetting recent conversations), word-finding difficulty, getting lost in familiar places. Middle: worsening memory, visuospatial disorientation, difficulty with finances and medications, personality changes, social withdrawal. Late: severe aphasia, inability to recognise family members (prosopagnosia), incontinence, dysphagia, immobility, and complete dependence. Vascular NCD: stepwise decline or fluctuating course; deficits depend on lesion location. Executive dysfunction (planning, organising, multitasking) is often more prominent than memory loss early on. Focal neurological signs (hemiparesis, gait abnormality) may be present. Lewy body NCD: fluctuating cognition (marked variations in alertness and attention), recurrent well-formed visual hallucinations (often of people or animals), REM sleep behaviour disorder (acting out dreams), and spontaneous parkinsonism (bradykinesia, rigidity, postural instability — not tremor-predominant). Extreme sensitivity to antipsychotics is characteristic. Frontotemporal NCD: two main variants — behavioural (personality change, disinhibition, apathy, loss of empathy, compulsive behaviours, dietary changes — typically onset age 45-65) and language (progressive aphasia with word-finding difficulty, impaired word comprehension, or effortful speech). Behavioural and psychological symptoms of dementia (BPSD) occur in ~90% at some point: agitation, aggression, wandering, sundowning, delusions (often paranoid — "someone is stealing from me"), depression, anxiety, and sleep disruption.

Age: the single strongest risk factor. Prevalence doubles every 5 years after age 65. About 5-8% of people >=60 have dementia, rising to ~25-50% by age 85-90. Genetics: APOE-e4 allele is the strongest genetic risk factor for late-onset Alzheimer's — one copy increases risk ~3-fold, two copies ~12-fold. First-degree family history increases risk 2-4 times. Rare autosomal dominant mutations in APP, PSEN1, and PSEN2 cause early-onset familial Alzheimer's (<5% of all Alzheimer's cases, onset typically age 30-60). Cardiovascular risk factors: hypertension (especially midlife), type 2 diabetes, hyperlipidaemia, obesity, smoking, and atrial fibrillation — these are particularly strong for vascular NCD but also increase Alzheimer's risk. Modifiable lifestyle factors (2020 Lancet Commission identified 12 modifiable risk factors accounting for ~40% of dementias): less education, hearing loss, traumatic brain injury, hypertension, excessive alcohol (>21 units/week), obesity, smoking, depression, social isolation, physical inactivity, air pollution, and diabetes. Other: Down syndrome (near-universal Alzheimer's pathology by age 40 due to APP gene triplication on chromosome 21), repeated mild TBI (e.g., contact sports — chronic traumatic encephalopathy), low educational attainment (reduced cognitive reserve).

Alzheimer's disease: extracellular amyloid-beta plaques (aggregated Abeta-42 peptide cleaved from APP by beta- and gamma-secretase) and intracellular neurofibrillary tangles (hyperphosphorylated tau protein) spread in a predictable pattern (Braak staging). Plaques accumulate first in the neocortex; tangles begin in the entorhinal cortex and hippocampus, then spread to association cortices. Neuronal loss and synaptic dysfunction follow. Cholinergic neurons in the nucleus basalis of Meynert degenerate early, causing acetylcholine deficiency that correlates with memory impairment. Vascular NCD: ischaemic brain injury from large-vessel strokes, small-vessel disease (lacunar infarcts, white matter hyperintensities), or cerebral amyloid angiopathy. Strategic infarcts in the thalamus, angular gyrus, or caudate can cause dementia from a single stroke. Lewy body disease: intracellular alpha-synuclein aggregates (Lewy bodies) deposit in cortical and limbic neurons, causing neurodegeneration. Overlap with Parkinson's disease pathology is substantial — timing determines diagnosis (dementia within 1 year of parkinsonism = Lewy body NCD; dementia >=1 year after established Parkinson's = Parkinson's disease dementia). Frontotemporal lobar degeneration: heterogeneous group — ~45% tau-positive (includes Pick's disease, progressive supranuclear palsy, corticobasal degeneration), ~50% TDP-43-positive, ~5% FUS-positive. Mutations in MAPT, GRN, and C9orf72 genes cause familial forms.

Approximately 55 million people worldwide live with dementia (WHO, 2023). This number is projected to reach 78 million by 2030 and 139 million by 2050, driven by population ageing in low- and middle-income countries (LMICs), which currently account for ~60% of cases. Prevalence: ~5-8% of adults >=60; the rate doubles roughly every 5 years after age 65 — approximately 3% at ages 65-74, 17% at 75-84, and 32% at >=85. Incidence: ~10 million new cases per year globally (1 new case every 3 seconds). Alzheimer's disease accounts for 60-70% of cases, vascular NCD ~15-20%, Lewy body ~5-10%, frontotemporal ~5%. In the US, ~6.7 million people aged >=65 have Alzheimer's disease (Alzheimer's Association, 2023).

Women are disproportionately affected — they account for ~65% of Alzheimer's deaths, partly due to longer life expectancy but also possibly greater vulnerability. Global cost of dementia care: estimated at $1.3 trillion annually (WHO), projected to reach $2.8 trillion by 2030. Dementia is the 5th leading cause of death in the US for those >=65.

Alzheimer's: the amyloid cascade hypothesis posits that Abeta-42 accumulation triggers a downstream cascade — tau hyperphosphorylation, neuroinflammation (microglial activation), oxidative stress, synaptic loss, and neuronal death. The cholinergic hypothesis focuses on degeneration of cholinergic neurons projecting from the nucleus basalis of Meynert to cortex and hippocampus. Both hypotheses inform current treatments. Hippocampal atrophy (medial temporal lobe) is an early and prominent finding, explaining the characteristic anterograde amnesia. Vascular: cerebrovascular lesions cause direct neuronal death (infarcts) or chronic hypoperfusion (white matter disease) leading to disconnection syndromes. The location of vascular injury determines the cognitive profile. Lewy body: cortical Lewy body distribution causes cognitive deficits; brainstem Lewy bodies cause parkinsonism; loss of cholinergic neurons in the basal forebrain and dopaminergic neurons in the substantia nigra contribute to both cognitive and motor symptoms. Visual hallucinations may arise from occipital Lewy body pathology and visual processing disruption. Frontotemporal: selective atrophy of frontal and/or temporal lobes. Behavioural variant shows predominant prefrontal atrophy (particularly orbitofrontal and anterior cingulate — governing social behaviour, empathy, and impulse control). Semantic variant affects the anterior temporal lobes. Non-fluent variant affects the left posterior frontal and insular regions.

Inventory (NPI) quantifies frequency and severity of BPSD.

DSM-5-TR criteria for Major NCD: (A) Evidence of significant cognitive decline from a previous level of performance in one or more cognitive domains (complex attention, executive function, learning and memory, language, perceptual-motor, social cognition), based on: (1) concern of the individual, a knowledgeable informant, or the clinician, AND (2) a substantial impairment in cognitive performance, preferably documented by standardised neuropsychological testing or, in its absence, another quantified clinical assessment. (B) The cognitive deficits interfere with independence in everyday activities (at minimum, need assistance with complex instrumental activities of daily living). (C) The cognitive deficits do not occur exclusively in the context of delirium. (D) The cognitive deficits are not better explained by another mental disorder (e.g., major depressive disorder, schizophrenia). Aetiological subtypes are then specified: due to Alzheimer's disease, vascular disease, Lewy body disease, frontotemporal lobar degeneration, Parkinson's disease, traumatic brain injury, HIV infection, Huntington's disease, prion disease, substance/medication use, another medical condition, multiple aetiologies, or unspecified. Specifiers: with or without behavioural disturbance (psychotic symptoms, mood disturbance, agitation, apathy, other). Severity: mild (difficulties with IADL), moderate (difficulties with basic ADL), severe (fully dependent). ICD-11 code: 6D80 (Dementia).

Cognitive testing: MMSE (quick screen, 10 minutes; limited ceiling sensitivity); MoCA (better for executive and visuospatial domains; available in >100 languages); formal neuropsychological battery when diagnostic uncertainty exists — tests memory (Rey Auditory Verbal Learning Test, Logical Memory from WMS), executive function (Trail Making Test B, Wisconsin Card Sort), language (Boston Naming Test, category/letter fluency), visuospatial function (Clock Drawing, Rey Complex Figure), attention (Digit Span). Laboratory workup to exclude reversible causes: CBC, CMP (glucose, electrolytes, renal function, liver function), TSH, vitamin B12, folate, syphilis serology (RPR/VDRL), HIV testing if risk factors present, ESR. Additional tests as indicated: calcium, cortisol, ammonia, heavy metals, coagulation studies. Neuroimaging: structural MRI — medial temporal lobe atrophy suggests Alzheimer's (visual rating scales: Scheltens MTA score); vascular lesions, white matter hyperintensities, and strategic infarcts suggest vascular NCD; frontal/temporal atrophy suggests frontotemporal NCD. CT head if MRI unavailable. PET imaging: FDG-PET shows hypometabolism patterns characteristic of different subtypes (temporoparietal in Alzheimer's, frontal in frontotemporal); amyloid PET (florbetapir, flutemetamol) detects amyloid plaques (positive in ~90% of Alzheimer's cases, but also in ~30% of cognitively normal older adults); tau PET (flortaucipir) detects neurofibrillary tangles and correlates with clinical severity. CSF biomarkers: reduced Abeta-42 and elevated phospho-tau and total tau support Alzheimer's diagnosis. Blood-based biomarkers (plasma Abeta-42/40 ratio, plasma p-tau217) are emerging as screening tools. DaTscan (dopamine transporter SPECT) distinguishes Lewy body NCD from Alzheimer's (reduced dopamine transporter uptake in caudate and putamen). EEG if Creutzfeldt-Jakob disease (CJD) is suspected — periodic sharp wave complexes.

Delirium: acute onset, fluctuating consciousness, attentional deficits, often with identifiable medical cause (infection, medications, metabolic derangement). Delirium and dementia frequently co-occur — delirium superimposed on dementia is common. Depression (pseudodementia): cognitive complaints with depressed mood, psychomotor retardation, and subjective memory difficulty; onset is typically subacute and temporally linked to depressive episode; antidepressant treatment improves cognition. Unlike Alzheimer's, depressed patients tend to say "I don't know" rather than confabulate. Mild NCD (mild cognitive impairment): cognitive decline that does not yet interfere with independence in daily activities; represents a risk state for progression to Major NCD (~10-15% per year for amnestic MCI progressing to Alzheimer's). Normal ageing: mild decline in processing speed and free recall is expected; recognition memory, vocabulary, and crystallised intelligence are preserved. Medication effects: anticholinergics, benzodiazepines, opioids, and anticonvulsants can cause cognitive impairment mimicking NCD, especially in older adults. Normal pressure hydrocephalus (NPH): the classic triad of gait disturbance, urinary incontinence, and cognitive decline — potentially reversible with CSF shunting. Hypothyroidism: cognitive slowing, fatigue, and depressed mood — reversible with thyroid hormone replacement. B12 deficiency: memory impairment, peripheral neuropathy, and macrocytic anaemia. Creutzfeldt-Jakob disease: rapidly progressive dementia (weeks to months), myoclonus, visual/cerebellar signs — distinct from the years-long course of Alzheimer's.

Treatment of Major Neurocognitive Disorder (dementia) involves pharmacological and non-pharmacological approaches aimed at slowing cognitive decline, managing behavioural symptoms, and supporting patients and caregivers. Pharmacotherapy for Cognitive Symptoms: Cholinesterase inhibitors (ChEIs) are first-line for Alzheimer's disease and provide modest improvement in cognition and daily functioning. Donepezil (5-10 mg/day) — once daily, well-tolerated, approved for all stages. Rivastigmine (patch 4.6-13.3 mg/24h or oral 3-12 mg/day) — also approved for Parkinson's disease dementia; patch formulation reduces GI side effects. Galantamine (8-24 mg/day extended-release) — dual mechanism (ChE inhibition + nicotinic receptor modulation). Common ChEI side effects: nausea, diarrhoea, bradycardia, vivid dreams, muscle cramps. Memantine (10-20 mg/day), an NMDA receptor antagonist, is used for moderate-to-severe Alzheimer's disease, alone or in combination with a cholinesterase inhibitor. It reduces glutamate-mediated excitotoxicity. Side effects include dizziness, headache, and constipation. Combination donepezil + memantine (Namzaric) is available. Anti-amyloid monoclonal antibodies: lecanemab (10 mg/kg IV every 2 weeks) — FDA fully approved (2023) for early Alzheimer's with confirmed amyloid pathology; slowed cognitive decline by ~27% over 18 months in the Clarity AD trial; major risk is amyloid-related imaging abnormalities (ARIA — cerebral oedema and microhaemorrhages), requiring MRI monitoring. Aducanumab (FDA accelerated approval 2021) — controversial due to mixed clinical trial results; reduces amyloid plaques but clinical benefit debated. Treatment of vascular risk factors (antihypertensives, statins, anticoagulants for atrial fibrillation, diabetes management) is essential for vascular and mixed dementias — preventing further strokes slows progression.

Managing Behavioural and Psychological Symptoms (BPSD): Non-pharmacological approaches are first-line: identifying and addressing triggers (pain, constipation, urinary tract infection, environmental overstimulation, unmet needs), structured routines, meaningful activities, music therapy, reminiscence therapy, validation therapy, bright light therapy for circadian disruption, and caregiver training in communication and de-escalation techniques. When non-pharmacological approaches are insufficient for severe agitation or psychosis, low-dose atypical antipsychotics (risperidone 0.25-1 mg, quetiapine 12.5-100 mg) may be used cautiously — FDA black box warning: antipsychotics increase mortality in elderly dementia patients (~1.6-1.7 fold) from cardiovascular and infectious causes. SSRIs (citalopram 10-20 mg, sertraline 25-100 mg) may help with depression and agitation — the CitAD trial showed citalopram reduced agitation but caused QTc prolongation at higher doses. Trazodone (25-100 mg) may help with sleep disturbance, agitation, and sundowning. Benzodiazepines are generally avoided due to paradoxical disinhibition, falls, and worsened cognition. Brexpiprazole received FDA approval (2023) for agitation in Alzheimer's disease. Caregiver Support: Caregiver education, respite care, support groups (Alzheimer's Association, local memory cafes), and community resources are essential components. Caregiver burnout and depression affect ~30-40% of dementia caregivers and require proactive attention, including screening and referral to counselling or support services. Safety and Planning: Home safety assessment (remove trip hazards, install grab bars, secure stove knobs, consider door alarms for wandering), driving evaluation (referral to occupational therapist for driving assessment — many jurisdictions require physician reporting), advance care planning (healthcare proxy, power of attorney, living will — optimally done early while the patient retains decision-making capacity), financial and legal planning, fall prevention (exercise programmes, medication review, vision correction), and transition planning for increasing levels of care (in-home support, adult day programmes, assisted living, memory care units, nursing home).

Alzheimer's disease: median survival from diagnosis is approximately 4-8 years, though range extends from 3 to 20 years. Younger age at onset paradoxically associates with faster decline. Progression follows a predictable pattern — mild stage (2-4 years), moderate stage (2-10 years), severe stage (1-3 years). The Clinical Dementia Rating (CDR) and Functional Assessment Staging (FAST) scales track progression. Vascular NCD: course depends on recurrence of cerebrovascular events — prognosis improves with aggressive vascular risk factor management. Median survival ~5 years. Lewy body NCD: slightly shorter survival than Alzheimer's (~5-7 years from diagnosis); marked by fluctuations and high caregiver burden. Frontotemporal NCD: median survival ~6-8 years from symptom onset; behavioural variant tends to have a somewhat longer course than language variants. Creutzfeldt-Jakob disease: rapidly fatal, typically within 1 year. Across all subtypes, poor prognostic indicators include older age at diagnosis, lower baseline cognition (MMSE <10), presence of extrapyramidal signs, behavioural disturbance, psychosis, and comorbid medical illness. Falls, aspiration pneumonia, malnutrition, and pressure ulcers are common end-stage complications and frequent causes of death.

Wandering: affects ~60% of patients at some stage; carries risk of falls, exposure, traffic accidents, and inability to return home. GPS tracking devices and door alarms reduce risk. Falls and fractures: impaired gait, visuospatial deficits, orthostatic hypotension (especially in Lewy body NCD), and medications contribute; hip fracture carries ~30% 1-year

mortality in dementia patients. Malnutrition and weight loss: forgetting to eat, difficulty using utensils, dysphagia, altered taste; weight loss >5% predicts faster decline. Aspiration pneumonia: the most common direct cause of death in advanced dementia; dysphagia screening and modified food textures reduce risk but cannot eliminate it. Pressure ulcers: immobility in late stages causes skin breakdown. Delirium superimposed on dementia: infections (UTI, pneumonia), medication changes, and hospitalisation frequently trigger delirium, which accelerates cognitive decline. Caregiver burden: 30-40% of caregivers develop depression; physical health deteriorates; financial strain from lost productivity and care costs. Abuse: individuals with dementia face increased risk of elder abuse (physical, emotional, financial, neglect) — estimated 5-10% prevalence. Polypharmacy: multiple medications increase adverse drug reaction risk, drug interactions, and anticholinergic burden.

The 2020 Lancet Commission identified 12 modifiable risk factors that together account for approximately 40% of dementias worldwide: less education, hearing loss, traumatic brain injury, hypertension, excessive alcohol, obesity, smoking, depression, social isolation, physical inactivity, air pollution, and diabetes. Addressing these factors represents the single greatest opportunity for dementia prevention. Specific recommendations: treat midlife hypertension (target systolic <130 mmHg); manage diabetes; treat hearing loss with hearing aids; maintain regular physical exercise (~150 minutes/week of moderate-intensity aerobic activity); stay cognitively and socially engaged; limit alcohol to <21 units/week; stop smoking; treat depression; reduce obesity; reduce air pollution exposure; prevent traumatic brain injury (helmet use, fall prevention). Mediterranean and MIND diets associate with lower dementia risk in observational studies. Patient and family education: dementia is a medical condition caused by brain disease, not a normal part of ageing; early diagnosis allows planning while the person can still participate in decisions; advance directives should be completed early; support services are available and should be used; driving safety must be assessed and documented; medication adherence can be supported with pill organisers and caregiver supervision.

The word "dementia" derives from Latin "de" (away from) + "mens" (mind). Ancient writers described senile cognitive decline, but systematic study began in the 19th century. Alois Alzheimer presented the case of Auguste Deter in 1906 — a 51-year-old woman with progressive memory loss, disorientation, and paranoia. At autopsy, he described the two hallmark pathological features: amyloid plaques and neurofibrillary tangles. Emil Kraepelin coined the term "Alzheimer's disease" in 1910. For decades, dementia was considered an inevitable consequence of ageing ("senility"). The cholinergic hypothesis emerged in the 1970s-80s when researchers showed that cholinergic neurons in the basal forebrain degenerate in Alzheimer's and that acetylcholine deficiency correlates with cognitive impairment. Tacrine became the first FDA-approved ChEI in 1993 (later withdrawn due to hepatotoxicity). Donepezil followed in 1996. The amyloid cascade hypothesis, proposed by Hardy and Higgins in 1992, has dominated Alzheimer's research for three decades. DSM-III (1980) codified dementia criteria. DSM-5 (2013) replaced "dementia" with "Major Neurocognitive Disorder" to reduce stigma and broaden the concept beyond Alzheimer's.

The anti-amyloid antibody era began with aducanumab (2021) and lecanemab (2023).

Dementia carries substantial stigma across cultures. In many societies, cognitive decline in older adults is dismissed as normal ageing or attributed to spiritual causes. The term "dementia" itself — literally "without mind" — contributes to stigma; DSM-5-TR's shift to "Major Neurocognitive Disorder" was partly motivated by this concern. Globally, dementia care falls disproportionately on women, who provide ~70% of informal caregiving. In low- and middle-income countries, most people with dementia remain undiagnosed and untreated, with limited access to diagnostic services, medication, or support. Cultural variations exist in attitudes toward truth-telling (some cultures prefer not to disclose a dementia diagnosis to the patient), end-of-life care (varying acceptance of palliative approaches versus aggressive intervention), and institutional versus family-based care. In high-income countries, dementia-friendly community initiatives aim to create environments where people with dementia can participate safely in daily life. Alzheimer's disease activism has accelerated research funding — the US National Alzheimer's Project Act (NAPA, 2011) set a goal to prevent and treat Alzheimer's by 2025.

Active research areas: (1) Anti-amyloid therapies — lecanemab and donanemab (Phase 3 results showed 35% slowing of decline) target amyloid clearance; debate continues about whether amyloid is a cause or marker of Alzheimer's. (2) Anti-tau therapies — semorinemab, antisense oligonucleotides, and tau vaccines aim to reduce neurofibrillary tangle formation. (3) Neuroinflammation — targeting microglial activation through TREM2 pathway modulation. (4) Blood-based biomarkers — plasma p-tau217 and Abeta-42/40 ratio can detect Alzheimer's pathology with ~90% accuracy, potentially replacing invasive CSF testing and expensive PET scans for screening. (5) Digital biomarkers — smartphone-based cognitive testing, speech analysis, gait sensors, and driving behaviour monitoring for early detection. (6) Prevention trials — the FINGER trial (Finland) demonstrated that a multi-domain intervention (exercise, diet, cognitive training, vascular risk monitoring) maintained or improved cognition in at-risk older adults. (7) Gene therapy and antisense oligonucleotides for familial Alzheimer's and frontotemporal dementia (targeting MAPT, C9orf72). (8) Lifestyle interventions — MIND diet, exercise, hearing aid use, and cognitive engagement are being studied in large randomised trials. (9) Health equity — addressing racial and socioeconomic disparities in dementia risk, diagnosis, and treatment access.

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StatPearls Dementia: https://www.ncbi.nlm.nih.gov/books/NBK557444/ Alzheimer's Association: https://www.alz.org NIMH: https://www.nimh.nih.gov NIA Alzheimer's Information: https://www.nia.nih.gov/health/alzheimers WHO Dementia Factsheet: https://www.who.int/news-room/fact-sheets/detail/dementia WHO ICD-11 code 6D80:

https://icd.who.int Alzheimer's Disease International: https://www.alzint.org Crisis: 988 (US Suicide & Crisis Lifeline); Text HOME to 741741 (Crisis Text Line) Note: Educational only. Not a substitute for professional care.