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Neurodegenerative Diseases Flashcards

A concise overview of neurodegenerative diseases, covering key concepts, brain regions, proteinopathies, and clinical features for learners.

30 cards~11 min
Neurodegenerative Diseases Flashcards — Qwi
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1What defines neurodegeneration?
Answer

Progressive dysfunction and loss of neurons

Loss leads to decline in functions controlled by those neurons.
2Selective vulnerability means that {{certain types of neurons}} are more susceptible to damage than others, which dictates the specific symptoms of each disease.
Answer

certain types of neurons

3The cerebellum coordinates movement and maintains balance.
Answer

True

4Difference between hippocampus and basal ganglia functions?
Answer

Hippocampus → memory, thinking | Basal ganglia → voluntary movement

5What term describes a disease with abnormal protein accumulation?
Answer

proteinopathy

Diseases where misfolded proteins aggregate, forming toxic clumps.
6Dementia is a syndrome characterized by an acquired {{decline in thinking abilities}} that significantly interferes with a person's ability to perform daily activities independently.
Answer

decline in thinking abilities

7Alzheimer disease is the most common cause of dementia in older adults.
Answer

True

8What are amyloid plaques composed of in Alzheimer disease?
Answer

extracellular amyloid beta deposits

Amyloid beta (Aβ) accumulates outside neurons forming plaques.
9Tau tangles consist of {{hyperphosphorylated tau protein}}.
Answer

hyperphosphorylated tau protein

10Early Alzheimer disease primarily affects the cortex.
Answer

False

Early AD impacts the hippocampus, impairing new memory formation.
11Which brain regions are affected early versus later in Alzheimer disease?
Answer

Early → Hippocampus | Later → Cortex

12What gross brain change characterizes Alzheimer disease?
Answer

Cortical atrophy with narrowed gyri and widened sulci

Ventricles enlarge as brain tissue is lost (ex vacuo).
13Frontotemporal degeneration often shows abnormal {{TDP-43}} protein clumps.
Answer

TDP-43

14Behavioral changes can appear before memory loss in frontotemporal degeneration.
Answer

True

15How do movement symptoms differ between Parkinson disease and Huntington disease?
Answer

PD → bradykinesia, rigidity, tremor | HD → chorea

16Which brain region loses dopaminergic neurons in Parkinson disease?
Answer

Substantia nigra

Located in the midbrain, its loss reduces dopamine for smooth movement.
17Parkinson disease features {{Lewy bodies}} as protein aggregates.
Answer

Lewy bodies

18Levodopa can increase brain dopamine levels and improve motor symptoms, but neuronal loss is progressive.
Answer

True

19What genetic mutation causes Huntington disease?
Answer

Expanded CAG repeat in the HTT gene

An autosomal dominant disorder; one altered copy is sufficient.
20The expanded CAG repeats produce a huntingtin protein with an expanded {{polyglutamine tract}}.
Answer

polyglutamine tract

21Individuals with more CAG repeats tend to have an earlier onset of Huntington disease.
Answer

True

22How do the genetic mechanisms of spinocerebellar ataxias and Friedreich ataxia differ?
Answer

SCAs → CAG repeat expansions (dominant) | Friedreich ataxia → FXN gene mutations (recessive)

23What protein deficiency characterizes Friedreich ataxia?
Answer

Low frataxin

Frataxin is essential for mitochondrial function; its deficiency impairs energy production.
24Amyotrophic lateral sclerosis is a progressive disease characterized by loss of both {{upper and lower motor neurons}}.
Answer

upper and lower motor neurons

25ALS presents with only lower motor neuron signs.
Answer

False

ALS shows both upper (spasticity, brisk reflexes) and lower (atrophy, fasciculations) signs.
26What are the hallmark signs of upper versus lower motor neuron involvement in ALS?
Answer

Upper → spasticity, brisk reflexes | Lower → atrophy, fasciculations

27How do abnormal prion proteins propagate disease?
Answer

They induce misfolding of normal PrP

The abnormal conformation converts normal prion protein into the pathogenic form, leading to exponential accumulation.
28Creutzfeldt‑Jakob disease causes {{rapidly progressive dementia}}.
Answer

rapidly progressive dementia

29Creutzfeldt‑Jakob disease shows significant inflammation in brain tissue.
Answer

False

Little to no inflammation is typically observed.
30Which disease shows early memory difficulty versus slowed movement as its primary early symptom?
Answer

Alzheimer disease → memory difficulty | Parkinson disease → slowed movement

Understanding Neurodegeneration

Neurodegeneration refers to the progressive dysfunction and loss of neurons. When neurons die, the functions they control—such as movement, memory, and cognition—decline, leading to the clinical syndromes observed in various disorders.

Selective Vulnerability

Not all neurons are equally susceptible. Certain types of neurons are more vulnerable, which explains why each disease produces a characteristic pattern of symptoms.

Key Brain Structures and Their Roles

  • Cerebellum: Coordinates movement and maintains balance.
  • Hippocampus: Essential for memory formation and thinking.
  • Basal ganglia: Controls voluntary movement.
  • Substantia nigra: Supplies dopamine to the basal ganglia for smooth motion.

Comparing Brain Regions

The hippocampus is primarily involved in memory, whereas the basal ganglia manage voluntary movement. This distinction helps differentiate disorders such as Alzheimer disease (memory‑focused) from Parkinson disease (movement‑focused).

Proteinopathies: Diseases of Abnormal Protein Accumulation

Many neurodegenerative disorders are classified as proteinopathies, where misfolded proteins aggregate into toxic clumps.

  • Alzheimer disease – extracellular amyloid‑beta deposits (amyloid plaques) and intracellular hyperphosphorylated tau protein (neurofibrillary tangles).
  • Parkinson disease – Lewy bodies containing α‑synuclein.
  • Frontotemporal degeneration – TDP‑43 protein aggregates.
  • Huntington disease – expanded polyglutamine tract in huntingtin protein.
  • Friedreich ataxia – deficiency of frataxin, a mitochondrial protein.
  • Creutzfeldt‑Jakob disease – misfolded prion protein that induces further misfolding of normal PrP.

Alzheimer Disease

Alzheimer disease is the most common cause of dementia in older adults. Early stages primarily affect the hippocampus, impairing new memory formation, while later stages involve widespread cortical atrophy. Grossly, the brain shows narrowed gyri, widened sulci, and enlarged ventricles (ex vacuo).

Frontotemporal Degeneration (FTD)

FTD often presents with behavioral changes before memory loss. Abnormal TDP‑43 protein clumps are a hallmark in many cases.

Parkinson Disease (PD)

PD is characterized by loss of dopaminergic neurons in the substantia nigra, leading to bradykinesia, rigidity, and tremor. Lewy bodies, composed of α‑synuclein, are the characteristic protein aggregates. Levodopa can increase brain dopamine and improve motor symptoms, but it does not halt neuronal loss.

Huntington Disease (HD)

HD results from an expanded CAG repeat in the HTT gene, producing a huntingtin protein with an elongated polyglutamine tract. The disease is autosomal dominant; longer repeat lengths correlate with earlier onset. Motor signs are dominated by chorea, contrasting with the rigidity of PD.

Spinocerebellar Ataxias (SCAs) vs. Friedreich Ataxia

SCAs are caused by dominant CAG repeat expansions, whereas Friedreich ataxia is a recessive disorder due to mutations in the FXN gene, leading to low frataxin levels and mitochondrial dysfunction.

Amyotrophic Lateral Sclerosis (ALS)

ALS is a progressive disease marked by loss of both upper and lower motor neurons. Upper motor neuron loss produces spasticity and brisk reflexes; lower motor neuron loss causes muscle atrophy and fasciculations. The disease does not affect only lower motor neurons.

Prion Diseases

Abnormal prion proteins propagate disease by inducing misfolding of normal PrP, creating a self‑amplifying cascade. Creutzfeldt‑Jakob disease, a prion disease, leads to rapidly progressive dementia with little to no inflammation in brain tissue.

Clinical Comparisons

DiseaseEarly SymptomPrimary Affected RegionKey Protein
Alzheimer diseaseMemory difficultyHippocampus → later cortexAmyloid‑beta, hyperphosphorylated tau
Parkinson diseaseSlowed movementSubstantia nigraα‑synuclein (Lewy bodies)
Huntington diseaseChoreaStriatumPolyglutamine‑expanded huntingtin
Frontotemporal degenerationBehavioral changesFrontal & temporal cortexTDP‑43
Creutzfeldt‑Jakob diseaseRapidly progressive dementiaDiffuse cortical involvementMisfolded prion protein

Key Takeaways

  • Neurodegeneration is defined by progressive neuronal loss, leading to functional decline.
  • Selective vulnerability determines which symptoms dominate each disease.
  • Protein aggregation (proteinopathy) is a common pathogenic mechanism across many disorders.
  • Understanding the sequence of brain region involvement aids early diagnosis (e.g., hippocampal loss in early Alzheimer disease).
  • Genetic mechanisms vary: repeat expansions (HD, SCAs), recessive gene loss (Friedreich ataxia), and prion conformational change (CJD).