- Defined as a progressive impairment of cognitive functions in the absence of any disturbances of consciousness.
- Increases with age.
- 5% in the 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 identifying 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 situations results in emotional outbursts in the dementia patient.
3. Focal neurological signs & symptoms:
- Seen in vascular dementia (multi-infarct dementia) corresponding to the 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 the involvement of the area of the brain:
- Cortical & Sub-cortical (As to area affected by dementing process first).
- 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.
- Conditions associated:
- Alzheimer’s disease – Prototype of cortical dementia.
- Creutzfeldt-Jakob disease, Pick’s disease & other frontotemporal dementias.
- Clinical features
- Early involvement of subcortical structures (basal ganglia, brain stem nuclei & cerebellum).
- Characterized by an 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.
- The occurrence of multiple cerebral infarctions (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 to 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 are similar to Alzheimer’s disease.
4. HIV related dementia:
- Presence of motor abnormalities or personality changes (apathy, emotional lability, or disinhibition).
5. Head trauma-related dementia:
- Sequelae of head trauma.
- Dementia pugilistica (punch drunk syndrome) can develop in boxers after repeated head trauma.
6. Frontotemporal Dementia (FTD):
- Pick’s disease:
- One pathological variant of FTD.
- Characterized by the presence of pick’s bodies.
- Earlier onset (45-65 years).
- Presents with behavioral symptoms & changes in personality with relative memory preservation.
- Depression in elderly patients mimicking dementia symptoms.
Management for dementia:
- mini-mental status examination (MMSE):
- Screening test.
- Evaluation of cognitive functions.
- A 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.
- Cognitive impairment in dementia is characterized by 4 A’s: amnesia, aphasia, apraxia & agnosia.
- A catastrophic reaction is subjective awareness of intellectual deficits in stressful situations results in emotional outbursts in dementia patients.
- Reversible causes of dementia include subdural hematoma, normal pressure hydrocephalus, intracranial tumors, and intracranial abscess.
- Alzheimer’s disease is the prototype of cortical dementia.
- Binswanger’s disease is also known as subcortical arteriosclerotic encephalopathy.
- Pick’s disease 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 functions in dementia is done using a screening test of a mini-mental status examination (MMSE).
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