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.
