Dementia and Cognitive Disorders

Dementia and Cognitive Disorders

Dementia and Cognitive Disorders

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Dementia: Overview & Types - Mind Maze Intro

  • Dementia: Acquired, persistent, global impairment of intellect, memory, and personality, without impaired consciousness.
  • Mild Cognitive Impairment (MCI): Cognitive decline greater than expected for age/education; daily activities largely preserved.
  • Major Domains Affected: Memory, language, attention, executive function, visuospatial skills.
  • Types: Alzheimer's (most common), Vascular, Lewy Body, Frontotemporal.

⭐ Dementia is a clinical syndrome, not a specific disease. Alzheimer's Disease is the leading cause.

Alzheimer's Disease - Plaque & Tangle Trouble

  • Pathophysiology: Extracellular amyloid-β (Aβ) plaques & intracellular neurofibrillary tau tangles cause neuronal death.
  • Genetics: APP, PSEN1, PSEN2 (early-onset, autosomal dominant); APOE ε4 (late-onset risk).
  • Clinical: Insidious onset. Progressive memory loss (early, anterograde), language (anomia), visuospatial issues.
  • Diagnosis:
    • Clinical; MMSE/MoCA (e.g., MMSE < 24/30).
    • CSF: ↓Aβ42, ↑Tau, ↑pTau.
    • Imaging (MRI): Medial temporal lobe (hippocampal) atrophy. PET for Aβ/tau. Alzheimer's Brain Changes: Macro and Micro
  • Management:
    • Cholinesterase inhibitors (Donepezil, Rivastigmine, Galantamine) for mild-moderate.
    • Memantine (NMDA antagonist) for moderate-severe.
    • Supportive care.

⭐ Early-onset AD (< 65 yrs) is often linked to autosomal dominant mutations in APP, PSEN1, PSEN2.

Vascular Dementia - Brain Blood Block

Caused by cerebrovascular disease (multi-infarct, small vessel disease).

  • Clinical Features:
    • Stepwise or progressive cognitive decline.
    • Focal neurological signs (e.g., weakness, reflex asymmetry).
    • Prominent executive dysfunction.
  • Risk Factors: Hypertension (HTN), Diabetes Mellitus (DM), Hyperlipidemia (HLD), smoking, stroke history.
  • Diagnosis:
    • Clinical assessment.
    • Hachinski Ischemic Score (> 7 suggests VaD).
    • Neuroimaging: infarcts, white matter lesions. MRI: Vascular dementia vs. healthy control

⭐ Stepwise deterioration with focal neurological deficits is characteristic of multi-infarct dementia (a type of Vascular Dementia).

FeatureLewy Body Dementia (LBD)Frontotemporal Dementia (FTD)Parkinson's Disease Dementia (PDD)
CognitionFluctuatingEarly behavioral/language changesLate cognitive decline
MotorParkinsonism (within 1 yr of cognitive decline)Often absent initiallyParkinsonism precedes dementia by >1 year
HallucinationsVisual (well-formed, recurrent)RareLess common than LBD
Key PathologyLewy bodies (α-synuclein)Tauopathy (e.g., Pick bodies) or TDP-43Lewy bodies (α-synuclein)
OtherREM sleep behavior disorder, neuroleptic sensitivityBehavioral (disinhibition, apathy) or language (PPA) variants
📌 MnemonicLBD: 'Fluctuating Parkinson's Hallucinations'

Delirium vs Dementia - Acute vs Chronic Chaos

Key Differentiating Features:

FeatureDeliriumDementia
OnsetAcute (hours-days)Insidious (months-years)
CourseFluctuatingProgressive
DurationDays-weeksMonths-years
AttentionImpaired, fluctuatesOften normal initially
ConsciousnessCloudedClear (until late stages)
HallucinationsOften visual/tactileLess common early
Psychomotor Activity↑ or ↓, or mixedOften normal early
ReversibilityOften reversibleRarely reversible (progressive)

⭐ Acute onset and fluctuating course with impaired attention are cardinal features of delirium.

High‑Yield Points - ⚡ Biggest Takeaways

  • Alzheimer's Disease: Most common dementia; amyloid-beta plaques and hyperphosphorylated tau tangles are key pathologies.
  • Vascular Dementia: Second most common; stepwise cognitive decline linked to cerebrovascular events and risk factors.
  • Lewy Body Dementia: Characterized by visual hallucinations, parkinsonism, and fluctuating cognition; alpha-synuclein pathology.
  • Frontotemporal Dementia: Presents with early personality changes, behavioral disinhibition, or progressive language dysfunction.
  • Normal Pressure Hydrocephalus (NPH): Classic triad of dementia, gait disturbance, and urinary incontinence; potentially reversible.
  • Creutzfeldt-Jakob Disease (CJD): Rare, rapidly progressive dementia with myoclonus and characteristic EEG/MRI findings.

Practice Questions: Dementia and Cognitive Disorders

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All are true regarding Fronto-temporal dementia except:

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Flashcards: Dementia and Cognitive Disorders

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_____ is seizure activity for > 5 mins (continuous or intermittent) without fully regaining consciousness between episodes, resulting in brain injury and possibly death

TAP TO REVEAL ANSWER

_____ is seizure activity for > 5 mins (continuous or intermittent) without fully regaining consciousness between episodes, resulting in brain injury and possibly death

Status epilepticus

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