Neurological disorder Flashcards
Define excitotoxicity.
Neurons can be become over-excited which leads to damage.
Do neurons self-replicate?
No: loss of neurons is a problem.
Define an a) intrinsic and b) extrinsic disorder?
a) Caused by genetics
b) Caused by external factors
Seizures are always caused by intrinsic factors. True or false?
False: they can be caused by a combination of the two.
If new neurons are born, where is this from?
Neural stem cells in the hippocampus or olfactory bulb.
Disruption of energy supply to a neuron can cause cell death. True or false?
True.
Neural circuits are refined over many years of usage. Why is it so damaging to lost this?
It cannot be exactly replicated.
Neurological disorders fall into 2 categories, a) extrinsic or b) intrinsic. Give examples of each?
a) Tumours, traumatic brain injury, infection (e.g. BSE), stroke
b) developmental abnormalities (Down’s), degeneration (Alzheimer’s)
Define a seizure.
‘Overly synchronous brain activity’
Seizures occur in which life stages?
Childhood or possibly old age: the times when most brain changes occur
What percentage of epileptic disorders have genetic causes?
30%
What percentage of epileptic disorders have acquired causes, e.g. head traumas etc.?
25%
Seizure disorders can be split into 2 categories. What are they?
- Generalised: no apparent local onset
2. Partial: begin from a focal point
What are the 3 types of generalised seizure and what do they do?
- Tonic-clonic: affects the whole brain. Largely associated with epilepsy.
- Absence: lapses of awareness often characterised by staring. Often go undetected.
- Atonic: a sudden loss of muscle tone causing temporary paralysis
What is another name for a) tonic-clonic and b) absence seizures?
a) Grand mal
b) Petit mal
Partial seizures are often characterised by a series of movements. Why?
Begins from a localised point, but as the seizure spreads along the primary motor cortex you can detect this progression in the person’s movements. Also it spreads to other cortices like the sensory, psychic and autonomic regions which you can see as the person may begin to lose vision, become emotional and begin to sweat or salivate.
The progression of partial seizures reflects cortical maps. True or false?
True.
Genetic defects that cause seizures often affect what?
Ion channels, thus altering the excitability of neurons.
What is photosensitive epilepsy?
Seizures triggered by flashing lights.
In which age bracket is photosensitive epilepsy most common?
Children and teenagers.
Spatial patterns can also trigger photosensitive epilepsy. True or false?
True.
What is the difference between dementia and Alzheimer’s?
Dementia is an impairment of thinking and memory. Alzheimer’s is a further progression of basic dementia whereby language and cognition is also impaired.
People with dementia struggle but can function. People with Alzheimer’s deteriorate until they cannot.
What is the difference between dementia and Alzheimer’s?
Dementia is an impairment of thinking and memory. Alzheimer’s is a further progression of basic dementia whereby language and cognition is impaired by degeneration of neurons.
People with dementia struggle but can function. People with Alzheimer’s deteriorate until they cannot.
What is vascular dementia?
Dementia brought on by a series of small strokes or changes to the brain’s blood supply.
What is fronto-temporal dementia?
Dementia that affects language, semantic memory.
What is Pick’s disease?
A disorder affecting personaliy, orientation and behaviour. More common in women.
What is Creutzfeldt-Jakob disease?
Rapid deterioration of mental function coupled with involuntary movements.
What is Huntingdon’s disease?
Characterised by involuntary movements. Genetic disease but onset is during later life.
What is Parkinson’s?
A progressive disorder of the CNS that causes involuntary movement and tremors.
Pick’s, Creutzfeldt-Jakob, Huntingdon’s and Parkinson’s sufferers all show signs of dementia. True or false?
True.
Alzheimer’s disease is a progressive disease that inevitably causes death. True or false?
True: on average there is an 8 year window between diagnosis and death.
The Mini Mental State Exam is sometimes used to indicate levels of impairment. Why is it not an accurate diagnostic tool?
Intelligent people may still score well with severe impairment, and stupid people may score badly despite not impairment.
Give 4 characteristic physical changes to the brain that occur in Alzheimer’s.
- Enlargement of the ventricles
- Thinning of the cortex
- Shrinkage of the hippocampus
- Plaques and tangles
Plaques are formed from amylase. In healthy people what is supposed to happen?
In healthy neurons secretase and gamma-secretase cut amylase precursor to release beneficial components for neuron metabolism.
Plaques are formed from amylase. What happens in Alzheimer’s sufferers?
Beta-secretase and gamma-secretase cut amylase precursor to give shorter than normal fragments. These are called beta-amyloids, and build up to form toxic plaques tat impair neuronal function.
What are tangles made from and how are they formed?
Tau protein: in healthy people tau protein stabilises microtubules. In Alzheimer’s tau protein falls apart. Microtubules are destroyed. The build up forms tangles INSIDE the neurons, disrupting internal transport and leading to cell death.
In relation to neurons, where are a) plaques and b) tangles found?
a) Outside/between cells
b) Within cells
Describe the general progression of Alzheimer’s disease.
Episodic memory begins, along with disorientation. Simple tasks become impossible. They become unable to speak, control their bowels, walk or understand what’s going on. They become very aggressive or frightened. It’s like development in reverse.
What are the 4 hypotheses for the cause of Alzheimer’s?
- Cholinergic hypothesis
- Myelination hypothesis
- Amyloid cascage hypothesis
- Metabolism hypothesis
Describe the cholinergic hypothesis.
Ach levels are greatly reduced in Alzheimer’s sufferers, thus it is thought that reduced Ach leads to reduced signalling which affects learning and memory and may cause plaques and tangles. Drugs that inhibit enzymes that break down Ach have been trialled but there are serious question marks.
Describe the myelination hypothesis.
Neurons in humans are myelinated, but this myelin becomes susceptible to damage at around age 50. They are the first neurons to show protein plaques and tangles. This may be why Alzheimer’s seems to be a uniquely human disease as we have more myelination that other species.
Explain the amyloid cascade hypothesis.
Changes in amyloid metabolism affects the synapses and neuronal functioning (i.e. neurotransmitter release), leading to the build up of plaques and tangles.
Explain the metabolism hypothesis.
Metabolic conditions in early life serve as conducive conditions for the formation of plaques and tangles.
There is thought to be a genetic component in Alzheimer’s. Mutations in which genes cause a) early onset and b) late onset Alzheimer’s?
a) Tends to be via familiar inheritance: mutations in the APP (amyloid precursor protein) and PS1/PS2 (presenilin) genes have been noted.
b) Inheritance is more complex but APOE (apolipoprotein E) has been implicated
Which work by Leinenga and Gotz, 2015 has found potential for new treatments for Alzheimer’s?
Plaques and tangles can be physically disrupted with ultrasound.
It has been found that immunisation against beta-amyloid can reduce cognitive function significantly. True or false?
True.
Describe the cholinergic hypothesis.
Ach levels are greatly reduced in Alzheimer’s sufferers, thus it is thought that reduced Ach leads to reduced signalling which affects learning and memory and may cause plaques and tangles. Drugs that inhibit enzymes that break down Ach have been trialled, however it affects motor function in the PNS. Effects cannot be localised.
