• Defined as a progressive impairment of cognitive functions in absence of any disturbances of consciousness.


  • Increases with age.
  • 5% in population older than 65 years; 20-40% in older than 85 years. 


1. Cognitive impairment:

  • Characterized by 4 A’s: amnesia, aphasia, apraxia & agnosia.


  • Memory impairment.
  • Can be episodic (memory for events) & semantic (memory for facts rules, words and language) & visuospatial deficits.


  • Disturbances of language function.


  • Inability to perform learned motor functions.
  • Eg: Difficulties in functions like buttoning the shirt or combing the hair.


  • Inability to interpret sensory stimulus.
  • Most common disturbance -‘prosopagnosia” – Inability identifing face.

Other cognitive impairments:

  • Disturbances in executive functioning (i.e. planning, organizing, sequencing & abstracting).

2. Behavioral & psychological symptoms:

  • Personality changes, hallucinations & delusions, depression, manic & anxiety symptoms, apathy, agitation, aggression, wandering circadian rhythm disturbances, catastrophic reaction.
    • Catastrophic reaction – Subjective awareness of intellectual deficits in stressful situation result in emotional outburst in dementia patient.

3. Focal neurological signs & symptoms:

  • Seen in vascular dementia (multi-infarct dementia) corresponding to site of vascular insults.


1. Depending on reversibility – Reversible dementia (15% patients) & Irreversible dementia.

Causes of reversible dementia:

  • Neurosurgical conditions (subdural hematoma, normal pressure hydrocephalus, intracranial tumors, intracranial abscess).
  • Infectious causes (meningitis, encephalitis, neurosyphilis, lyme disease).
  • Metabolic causes (vitamin B12 or folate deficiency, niacin deficiency, hypo and hyperthyroidism, hypo & hyperparathyroidism).
  • Others (drugs and toxins, alcohol abuse, autoimmune encephalitis).

2. Depending on involvement of area of brain:

  • Cortical & Sub-cortical (As to area affetced by dementing process first).

Cortical dementias: 

Clinical features: 

  • Characterized by early involvement of cortical structures & hence, early appearance of cortical dysfunction.
  • Amnesia, apraxia, aphasia, agnosia & acalculia (impaired mathematical skills) indicating cortical involvement.

Subcortical dementia: 

Clinical features

  • Early involvement of subcortical structures (basal ganglia, brain stem nuclei & cerebellum).
  • Characterized by early presentation of motor symptoms (abnormal movements like tics, chorea, dysarthria).
  • Significant disturbances of executive functioning.
  • Prominent behavioral & psychological symptoms (apathy, depression, bradyphrenia (slowness of thinking).

Conditions associated: 

  • Parkinson’s disease, Wilson’s disease, Huntington’s disease, multiple sclerosis, progressive supranuclear palsy, normal pressure hydrocephalus.

Other types of dementia:

  • Vascular dementia (multi-infarct dementia), lewy body disease (dementia with lewy body), HIV related Dementia, frontotemporol dementia (FTD) & pseudodementia

1. Vascular dementia (multi-infarct dementia):

  • 2nd most common type of dementia.
  • History of stroke.


  • Occurrence of multiple cerebral infarction (due to occlusion of cerebral vessels by arteriosclerotic plaques or thromboemboli) → progressive deterioration of brain functions →  dementia.
  • Acute exacerbations corresponding to new infarcts → Stepwise deterioration of symptoms (step-ladder pattern).


  • Management of risk factors & cholinesterase inhibitors.

2. Binswanger’s disease:

  • Also referred as “subcortical arteriosclerotic encephalopathy”.
  • Characterized by multiple small white matter infarctions —> Result in subcortical dementia symptoms.

3. Lewy Body Disease (Dementia with Lewy Body):

  • Clinical features similar to Alzheimer’s disease.

Pick’s dlsease: 

  • One pathological variant of FTD. 
  • Characterized by presence of pick’s bodies.
  • Earlier onset (45-65 years).
  • Presents with behavioral symptoms & change in personality with relative memory preservation.

7. Pseudodementia:

  • Depression in elderly patients mimicing dementia symptoms.

Management for dementia:

  • mini mental status examination (MMSE):
    • Screening test.
    • Evaluation of cognitive functions.
    • Score of less than 24 (out of a maximum 30) – Suggestive of dementia.


  • Cholinesterase inhibitors  – Donepezil, rivastigmine, galantamine & tacrine.
  • NMDA receptor antagonist – Memantine.
  • Symptomatic treatment – For behavioral & psychological symptoms of dementia.
    • Includes antidepressants, antipsychotics & benzodiazepines.

Exam Important

  • Cognitive impairment in dementia is characterized by 4 A’s: amnesia, aphasia, apraxia & agnosia.
  • Catastrophic reaction is subjective awareness of intellectual deficits in stressful situation result in emotional outburst in dementia patient.
  • Reverslble causes of dementia includes subdural hematoma, normal pressure hydrocephalus, intracranial tumors, intracranial abscess.
  • Alzheimer’s disease is the prototype of cortical dementia.
  • Binswanger’s disease is also known as subcortical arteriosclerotic encephalopathy.
  • Pick’s dlsease is one pathological variant of FTD characterized by earlier onset & presence of pick’s bodies.
  • Depression in elderly patients may mimic symptoms of dementia and hence is known as pseudodementia.
  • The evaluation of cognitive tunctions in dementia is done using screening test of mini mental status examination (MMSE).
Don’t Forget to Solve all the previous Year Question asked on DEMENTIA

Module Below Start Quiz

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