Dementia Types and Causes Quiz

Dementia Types and Causes

• Dementia encompasses any progressive brain disease.
• Alzheimer's Disease (AD) is the most common, accounting for approximately 62% of cases.
• Vascular dementia accounts for about 17%.
• Mixed dementia makes up around 10% of cases.

Vascular Dementia

• Second most common type in the UK and Europe.
• Stems from impaired blood flow to the brain (strokes).
• Often caused by a series of mini-strokes.
• Strokes result from blocked arteries (thrombosis) or bleeding (hemorrhage).
• Blocked arteries are the leading cause.
• Strokes cause oxygen deprivation, cell death, and progressive brain damage.
• Risk factors include hypertension, high cholesterol, smoking, and diabetes.
• Symptoms can appear or worsen abruptly ("stepped" progression).
• This type of dementia often impacts the frontal lobes, leading to concentration issues, confusion, and problems with organizing thoughts and behavior.
• Early signs may include apathy.
• Can cause physical weakness or paralysis, due to motor cortex involvement.

Focal Dementias

• Brain damage is limited to specific areas initially, expanding over time.

Frontotemporal Dementias (FTD)

• Relatively rare, affecting people in their 40s and 50s.
• Different pathology than Alzheimer's (no amyloid plaques, sometimes "Pick bodies").
• Types include frontal variant (70% of cases), semantic dementia, and posterior cortical atrophy.
• Frontotemporal dementia's frontal variant creates these symptoms:
  • Personality changes (rudeness, apathy, impatience).
  • Lack of inhibition (inappropriate language/behavior).
  • Diminished empathy.
  • Compulsive behaviors (hoarding, hyperfixation).
  • Overeating.

Semantic Dementia

• Atrophy of anterior temporal lobes.
• Preserves the hippocampus (in some parts of the brain).
• Progressive loss of conceptual knowledge (from words and pictures).
• Good spoken language and memory for recent events retained.
• Impaired factual memory retrieval, with preserved non-verbal reasoning.

Posterior Cortical Atrophy

• Focal alzheimer-like pathology, impacting the posterior parietal cortex.
• Symptoms include vision problems, difficulty recognizing faces/objects (agnosia), and spatial impairment.
• Reading, writing, and dressing issues are common.
• Memory, spoken language, and thinking abilities are usually intact until later stages.

Subcortical Dementias

• Affect structures outside the main cortex, impacting movement, and cognitive control.

Huntington's Disease

• Rare (0.01%).
• Gene mutation (dominant).
• 50% chance of inheritance.
• Basal ganglia affected first, leading to cortical atrophy, onset between 30-45.
• Early symptoms: restlessness, clumsiness, involuntary movements (chorea).
• Cognitive changes: poor concentration, working memory and executive function problems.
• Emotional changes: aggression, antisocial behavior, mood instability.

Parkinson's Disease

• Affects individuals (especially those over 60).
• Degeneration in substantia nigra (dopamine deficiency).
• Slow progression, with noticeable symptoms when dopamine levels drop by 80%.
  • Treatment: levo-dopa to increase dopamine.
• Negative symptoms: akinesia (loss of movement initiation), bradykinesia (slowed movement).
  • Disturbed speech, impaired articulation.
• Positive symptoms: tremor (at rest), rigidity, involuntary movements, posture changes.
• Later stages frequently exhibit cognitive decline: decreased concentration, working memory issues, slowed thinking.

Other Causes

• Repetitive head injuries (chronic traumatic encephalopathy - CTE) can lead to dementia. This is often seen in contact sports like boxing and football, where cumulative blows can cause damage.