The most common cause of dementia is?

Appeared in: IGNOU Post B. SC. Nursing entrance-2019

Explanation

Alzheimer's disease (AD) is the most prevalent form of dementia, responsible for 60-80% of all cases.
It is a progressive neurodegenerative disorder characterized by the accumulation of amyloid plaques and tau tangles in the brain.
The clinical presentation typically begins with gradual memory impairment, particularly for recent events, and progresses to affect other cognitive domains.

Why Other Options Were Wrong

Option A: Multiple sclerosis is an autoimmune, demyelinating disease of the central nervous system. While it can cause cognitive problems, it is not a primary cause of dementia and is far less common than Alzheimer's disease.
Option B: This condition, also known as neurosyphilis, is now extremely rare due to the widespread availability and use of antibiotics to treat syphilis infection.
Option D: Multi-infarct lesions cause vascular dementia, which is the second most common type of dementia, not the most common. It accounts for a smaller percentage of cases than Alzheimer's disease.

Related Visual

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of Dementia as background academic context rather than a clinical decision trigger.
Accurate diagnosis of the specific type of dementia is critical as it guides prognosis, treatment (e.g., cholinesterase inhibitors for AD), and family counseling.
Nurses play a vital role in observing and documenting the pattern of cognitive decline. A gradual, steady decline points towards Alzheimer's, whereas a stepwise deterioration suggests vascular dementia.
A 'What if?' scenario: If a patient presented with prominent visual hallucinations and parkinsonism early in their cognitive decline, the most likely diagnosis would shift from Alzheimer's to Dementia with Lewy Bodies (DLB).

How to Approach the Question

Identify the core question, which asks for the 'most common' cause of dementia. This signals a question about prevalence or epidemiology.
This is a factual recall question. Access your knowledge of common neurological disorders.
Evaluate each option based on how frequently it causes dementia.
Recall that Alzheimer's disease is the most frequent cause, affecting the majority of dementia patients.
Distinguish it from vascular dementia (caused by multi-infarct lesions), which is the second most common, and other much rarer causes like neurosyphilis or MS-related dementia.

Concept Tested & Keywords

Concept Tested: Etiology of Dementia
Stem keywords: dementia, most common cause
Lead-in keywords: most common

Question ID

QGTpsvwncUYqYqgb2lQO8S

Reference Book

E6 Medicine Davidson Principles Practice 24e p. 1212-1214

E6 Medicine Harrison 22e Part 1 p. 235-237

E6 Robert Boland, Marcia L. Verduin - Kaplan and Sadock's Comprehensive Text of Psychiatry-Wolters Kluwer Health (2024) (pp 1-16525 of 16525) p. 4058-4061

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