10/03/2026
Types of Dementia
Definition:
• Dementia is a syndrome of progressive cognitive decline affecting memory, thinking, behavior, and daily functioning.
1️⃣ Alzheimer’s Disease (AD)
• Most common type (~60–70% of cases)
• Pathology: β-amyloid plaques, neurofibrillary tangles (tau protein)
• Clinical Features:
• Gradual memory loss (episodic memory first)
• Disorientation, language difficulty
• Later: behavioral changes, functional decline
2️⃣ Vascular Dementia
• Second most common
• Cause: Cerebrovascular disease (strokes, chronic ischemia)
• Clinical Features:
• Stepwise cognitive decline
• Focal neurological deficits
• Often coexists with Alzheimer’s (mixed dementia)
3️⃣ Lewy Body Dementia (LBD)
• Cause: α-synuclein deposition in neurons
• Clinical Features:
• Fluctuating cognition
• Visual hallucinations
• Parkinsonism (rigidity, bradykinesia)
• Sensitive to antipsychotics → avoid typical neuroleptics
4️⃣ Frontotemporal Dementia (FTD)
• Cause: Degeneration of frontal and temporal lobes
• Clinical Features:
• Behavioral variant: disinhibition, apathy
• Language variant: progressive aphasia
• Onset usually younger (50–60 years)
5️⃣ Parkinson’s Disease Dementia
• Occurs in advanced Parkinson’s disease
• Parkinsonism precedes cognitive decline by >1 year
• Hallmarks: bradykinesia, rigidity, tremor
6️⃣ Mixed Dementia
• Combination of Alzheimer’s + vascular or other types
• Common in older adults
7️⃣ Reversible / Secondary Dementias
• Causes:
• Hypothyroidism
• Vitamin B12 deficiency
• Chronic alcohol use
• Normal pressure hydrocephalus
• Treating the underlying cause can improve cognition
Investigations
• Blood tests: B12, thyroid, electrolytes
• Imaging: MRI/CT to rule out vascular lesions, tumors
• Cognitive tests: MMSE, MoCA
• Memory loss early → Alzheimer’s
• Stepwise decline → Vascular dementia
• Fluctuating cognition + visual hallucinations → Lewy body dementia
• Behavioral changes in younger adults → students