GeriQBank · Paper II · Q28

Differentiating features of delirium, depression and dementia

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Topic: Dementia & Cognition
Chapter: BPSD, Caregiver Support, Reversible Dementias, MCI & Vascular Dementia
Years asked: Not recorded in the source
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Attempt it firstOutline your answer as a 15-mark answer before revealing it — definition, causes, evaluation, management and the geriatric angle.Reveal answer

7-Mark Answer

Textbook Core — 6 Points

The three screening questions. Any older person presenting with confusion should be assessed with three questions that separate the three D’s: (i) Has the onset of abnormalities been acute — over a few hours or a few days? (delirium); (ii) Are there physical factors — medical illness, sensory deprivation, drugs — that may contribute? (delirium or reversible dementia); (iii) Are psychological factors — depression and/or psychosis — contributing to or complicating the impairment? (depression). These questions focus on identifying treatable conditions which, when diagnosed and treated, might result in substantially improved cognitive function.

Delirium. An acute or subacute alteration in mental status, with prevalence of about 15% on admission in hospitalised geriatric patients and incidence up to one-third; it may persist for days or weeks and so is common in post-acute care. Key features are disturbance of consciousness, change in cognition not better accounted for by dementia, development over hours to days with fluctuation through the day, and evidence of a causative medical condition, substance intoxication, side effect or withdrawal. The disturbances of consciousness and attention, with sudden onset and fluctuating cognitive status, are the major features that distinguish delirium from other causes of impaired cognitive function. There is difficulty sustaining attention, sensory misperception (illusions), fragmented or disordered stream of thought, psychomotor disturbance (restlessness, picking at bedclothes, or sluggishness and drowsiness) and emotional disturbance; neurological signs other than asterixis are uncommon.

Dementia. A clinical syndrome of sustained loss of intellectual function and memory sufficient to cause dysfunction in daily living, with a gradually progressing course over months to years and no disturbance of consciousness. Loss of functional ability due to impaired cognition is the feature that distinguishes dementia from MCI.

Depression (“depressive pseudodementia”). Refers to patients with reversible or partially reversible impairment of cognitive function caused by depression. Depression may coexist with dementia in more than one-third of outpatients with dementia and in an even greater proportion in nursing homes, and the relationship is complex: many patients with early dementia become depressed, and depression may be diagnosed in many patients before they become demented. Helpful clinical characteristics are prominent complaints of memory loss, patchy and inconsistent cognitive deficits on examination, and frequent “don’t know” answers.

Tools and testing. Delirium is screened with the Confusion Assessment Method (CAM), which requires acute onset and fluctuating course, AND inattention, AND either disorganised thinking OR altered level of consciousness; inattention is tested by months of the year backward, days of the week backward, or digit span backward, and disorganised thinking by orientation to time and place and observation of illogical flow of ideas. Depression is quantified with the Geriatric Depression Scale, or the Cornell Scale for Depression in Dementia where dementia coexists. Detailed neuropsychological testing, performed by someone skilled in these tools, is helpful in differentiating depression and dementia, and where uncertainty persists after full assessment, a careful trial of an antidepressant is justified to facilitate diagnosis and improve function and quality of life.

Why the distinction matters, and the pitfalls. Differentiating delirium from dementia is important because the latter is not immediately life-threatening, and inappropriately labelling a delirious patient as demented may delay diagnosis of serious and treatable underlying medical conditions. It is not possible to diagnose dementia while delirium is present in a patient with previously normal or unknown cognitive function — the diagnosis of dementia must await treatment of all potentially reversible causes of delirium. Conversely, attributing symptoms common in dementia — disorientation, agitation — to the dementia itself leads to under-diagnosis of delirium and to missing a serious underlying illness. The practical strategy when both are possible is to focus on the core diagnostic symptoms of abnormal attention and awareness and altered level of consciousness or alertness, rather than on the behavioural symptoms — especially useful when no reliable informant is available. Sundowning — increased confusion at night, especially in pre-existing dementia — is probably related to sensory deprivation in unfamiliar surroundings, and such patients may actually meet the criteria for delirium.

Latest Update — 1 Point

Delirium superimposed on dementia (DSD) is now a defined clinical entity in its own right, present in a large proportion of hospitalised people with dementia and associated with prolonged length of stay, accelerated long-term cognitive decline and poor outcomes. Detection has been simplified by ultra-brief validated tools — the 4AT, the 3D-CAM, the brief CAM (bCAM) and the Ultra-Brief 2-item screener — which are practical at the bedside and in emergency departments; the NICE delirium guidance (updated 2023) and Indian practice both favour the 4AT because it requires no special training and can be completed in under two minutes even in an uncooperative patient. Alongside this, the “depression–dementia continuum” is now better characterised: late-life depression with cognitive impairment carries a substantially raised risk of subsequent dementia, so such patients require structured cognitive follow-up rather than reassurance, and plasma p-tau217 can help distinguish depression-related cognitive impairment from underlying Alzheimer pathology in specialist settings.

Master Differentiation Table

Feature Delirium Dementia Depression

Onset Acute — hours to days Insidious — months to years Subacute — weeks to months, often datable Course Fluctuating through the day, Slowly progressive, stable Diurnal variation, typically worse worse at night through the day in the morning Consciousness Reduced clarity of awareness Clear until terminal stages Clear — the defining feature Attention Impaired — cardinal feature Normal early, impaired late Poor concentration but attention preserved on testing Orientation Impaired, fluctuating Impaired as disease advances Usually intact Memory complaint Not volunteered Concealed or minimised; Prominently complained of informant reports it Cognitive deficits Global, fluctuating Consistent, progressive Patchy and inconsistent Answers on testing Wrong, inconsistent, distractible Near-miss or confabulated Frequent “don’t know”, poor answers, effortful effort Psychomotor activity Hyperactive, hypoactive or Usually normal until late Retardation or agitation mixed; picking at bedclothes Perception Illusions and hallucinations Hallucinations late (early in DLB) Uncommon; mood-congruent if common (visual) psychotic Thought Fragmented, disordered, Impoverished Themes of guilt, worthlessness, illogical hopelessness Sleep–wake cycle Markedly disrupted, reversed Fragmented, sundowning Early morning waking Neurological signs Uncommon except asterixis Late focal or extrapyramidal Absent signs Reversibility Usually reversible if the cause Largely irreversible (<4% Reversible with treatment is treated reversible)

Screening tool CAM, 4AT, 3D-CAM MMSE, MoCA, informant history GDS, Cornell Scale Current Practice Update Area Textbook Current recommendation Exam approach Delirium screening CAM (4 criteria) 4AT and 3D-CAM for ultra-brief Name CAM first, then the 4AT as bedside and emergency use the practical update Delirium with dementia Recognised as difficult DSD is a defined entity with Use the phrase “delirium worse outcomes; focus on superimposed on dementia”

attention and level of consciousness, not behaviour Depression with cognitive High risk of later dementia; Confirmed; plasma p-tau217 Mention structured follow-up, not impairment follow closely can identify underlying AD reassurance pathology Exam One-Liners The three discriminators: onset, attention and level of consciousness.

Delirium: acute, fluctuating, inattentive, clouded consciousness.

Dementia: insidious, progressive, clear consciousness.

Depression: prominent memory complaints, patchy deficits, “don’t know” answers.

Delirium prevalence ~15% on admission, incidence up to one-third.

CAM = acute onset and fluctuation + inattention + (disorganised thinking OR altered consciousness). Neurological signs other than asterixis are uncommon in delirium.

You cannot diagnose dementia while delirium is present.

Depression coexists with dementia in over one-third of outpatients.

Sundowning patients may actually meet criteria for delirium.

When both are possible, judge by attention and alertness, not by behaviour.

CONSOLIDATED NIGHT-BEFORE MASTER SHEET

Questions 21–28 on One Page

The single fact most likely to earn # Topic Marks the mark 21 BPSD — types, aetiology, 15 + 7 90–98% develop at least one investigation, management, NPS; DICE; brexpiprazole drugs 2023 and dextromethorphan– bupropion 2026 now licensed for agitation 22 Non-pharmacological 7 Caregiver-directed interventions:

management of behavioural 23 trials, ~3300 dyads, effect disturbance size 0.34 — greater than antipsychotics 23 Addressing caregiver stress 7 Zarit Burden Interview; caregiver counselling prevents caregiver depression; treat the dyad 24 Innovations to ease caregiver 7 ICT delivery of proven burden interventions; telemedicine prevents psychiatric admissions from LTC homes 25 Reversible dementias 7 <4% truly reversible; treatment does not guarantee reversal; PENS 2025 — gait improves, cognition does not 26 Mild cognitive impairment 7 >20% of those 71+ have CIND; 15–20% convert per year; anti-amyloid antibodies now licensed at MCI stage 27 Vascular dementia 7 VCI is the umbrella term; ChEIs not recommended for pure VaD, use in mixed; SPRINT MIND for prevention 28 Delirium vs depression vs 7 Judge by onset, attention and dementia level of consciousness; you cannot diagnose dementia during delirium The Twelve Numbers to Carry Into the Hall Fact Number Dementia patients developing at least one NPS 90–98% Caregiver intervention effect size on behavioural symptoms 0.34 Brexpiprazole CMAI effect size ~0.35 AXS-05 relapse rate versus placebo (ACCORD-2) 8.4% vs 28.6% Truly reversible dementias <4% Depression coexisting with dementia in outpatients >1/3 Cognitive impairment without dementia, age 71+ >20% MCI annual conversion to dementia 15–20% VCI prevalence over age 65 ~5% White matter lesion threshold, NINDS-AIREN >25% of white matter Delirium prevalence on admission / incidence in hospital ~15% / up to one-third PENS trial gait velocity gain (iNPH shunting) 0.21 m/s; 80% vs 24% improved Indian Policy Sentences to Drop Into Any of These Answers LASI-DAD: dementia prevalence 7.4% in adults 60+, about 8.8 million cases, projected 16.9 million by 2036; caregiving data from 4196 informants (2025) confirm measurable caregiver stress and mental-health impact Over 90% of dementia care in India is family-provided, with scarce respite and long-term care infrastructure — the case for digital and community-based caregiver support NPHCE — Regional Geriatric Centres, district geriatric units and CHC/PHC geriatric clinics: the platform for cognitive and caregiver screening National and District Mental Health Programme — the practical route for BPSD management and caregiver depression AB-PMJAY and the Ayushman Vay Vandana Card — cover for all citizens aged 70 and above regardless of income Maintenance and Welfare of Parents and Senior Citizens Act, 2007 — legal remedy where caregiving breaks down Rights of Persons with Disabilities Act, 2016 — disability certification including chronic neurological conditions and mental illness Rashtriya Vayoshri Yojana / AVYAY — assistive devices and senior citizen welfare Elder Line 14567 — national toll-free helpline ARDSI — caregiver training, day care, support groups, Dementia India reports WHO ICOPE (2nd edition) — cognitive decline as one of the six domains of intrinsic capacity screened in primary care End of compilation — Questions 21 to 28.

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References

PAPERS-2-3-4_COMBINED.pdf — page 319
GeriQBank source PDF — p. 319

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