Ageing of the Central Nervous System Flashcards
At which age does the brain begin to decline in volume?
At which rate does the brain decline in volume?
- Brain volume starts to decline at ~40 years of age.
- The volume declines at 5% per decade.
What changes in the brain explain the decline in brain volume with age?
There is a decline in the volume of neurones (the number of neurones stays the same).
List 5 areas of the brain in order of susceptibility to volume loss with age.
1 - Prefrontal cortex.
2 - Hippocampus (hence memory loss).
3 - Corpus striatum.
4 - Temporal lobes.
5 - Cerebellum.
List the 3 types of memory.
Which of these is affected by age?
1 - Sensory memory (no further subcategories).
2 - Short-term / working memory (no further subcategories).
3 - Long-term memory.
- Long-term memory is affected by age.
List the subcategories of long-term memory.
What is the difference between the subcategories?
1 - Explicit / declarative memory - conscious.
2 - Implicit memory - unconscious.
List the subcategories of implicit memory.
1 - Priming memory.
2 - Procedural memory.
List the subcategories of explicit / declarative memory.
1 - Episodic memory - events and experiences.
2 - Semantic memory - facts and concepts.
List 3 cellular changes in the brain other than an increase in neuronal volume that occur with age.
1 - The number of oligodendrocytes increase.
2 - The number of microglia increase.
3 - Microglia take an inflammatory phenotype (this makes them more liable to damaging neurones in response to infection).
4 - Microglia become senescent (so are unable to undergo phagocytosis).
How do astrocytes change with age?
Astrocytes remain stable with age.
List 3 neurotransmitters which decrease in production with age.
Give an example of a disease that is associated with a decreased production of each neurotransmitter.
1 - Dopamine - Parkinson’s.
2 - Acetylcholine - Alzheimer’s.
3 - GABA - Huntington’s.
What might be seen on a CAT scan in an ageing brain?
What causes this?
With which disease is this associated with?
- Radiopaque white matter degeneration.
- This is caused by many small, asymptomatic strokes that can accumulate.
- They are associated with dementia.
Give an example of a drug treatment for dementia.
Acetylcholinesterase inhibitors can be used to treat dementia.
Describe the pathophysiology of Alzheimer’s disease.
- Normally, amyloid precursor protein (APP), which stabilises the neurone cell membrane, is cleaved by secretase and is reabsorbed into the cell.
- With age, there is a decrease in function of secretase, which causes an accumulation of A-beta fibres, which are insoluble protein byproducts of APP cleavage.
- A-beta fibres accumulate into ‘amyloid plaques’ and act as inflammatory stimuli when cleared by microglia, causing cell damage.
- Structures known as ‘tangles’ also form when a protein components known as ‘tau’ from microtubules in axons dissociate from the microtubule, misfold and aggregate in the cell body.
- Tau aggregates mediate the effects of A-beta.
List 8 risk factors for Alzheimer’s disease.
1 - ApoE 4 gene.
2 - Less education.
3 - Hearing loss.
4 - Hypertension.
5 - Obesity.
6 - Smoking.
7 - Depression.
8 - Diabetes.
What is the main difference between the symptoms of dementia and Alzheimer’s disease?
Dementia primarily affects memory whereas Alzheimer’s disease affects both memory and cognitive function.
What is delirium?
What causes delirium?
- Delirium is an acute neuropsychiatric condition that affects attention, alertness and cognition.
- It is caused by acute activation of microglial cells in the brain.
List 3 symptoms of Parkinson’s disease.
1 - Tremor.
2 - Bradykinesia.
3 - Hypertonia.
