6.5 Dementia Flashcards
Define dementia
- Collection of symptoms that are caused by disorders affecting the brain
- Affects thinking, behaviour and everyday life
- Interferes with normal social/working life
Is dementia a disease?
No. it is a group of diseases.
What are some causes of dementia?
- Alzheimer’s
- Vascular dementia
- Dementia with lewy bodies
- Parkinson’s Disease Dementia
What causes vascular dementia?
Damage to brain tissue caused by decreased blood flow (multiple emboli/diffuse small vessel disease)
Alzheimer’s is a neurodegenerative disease that causes loss of neurons, particularly in the…
Cortex
What is the role of amyloid precursor protein (APP)?
- Neuron growth and repair
- Used, broken down, and recycled
Which enzyes usually break down Amyloid Precursor proteins?
alpha and gamma secretase (secretion = soluble)
Which enzyme, when cleaving amyloid precursor protein, causes formation of amyloid beta?
Beta secretase
What plaques are formed when beta secretase cleaves amyloid precursor protein? What does this cause?
- Beta amyloid plaques
- Can interfere with neuron to neuron signalling, causing neurological deficits that lead to Alzheimer’s
- Can also start up an immune response, causing immune response
- Can also lead to amyloid angiopathy
How are neurofibrillary tangles thought to be formed? What are the consequences of this?
- Beta amyloid buildup prompts phisphate deposition on tau within microtubules
- Causes conformational shape change that leads to tau leaving microtubules and forming tangles
- Disrupts microtubules, and can lead to apoptosis
What is the level of memory impairment between age-based memory impairment and dementia?
Mild cognitive impairment
How is dementia different from age based memory loss and mild cognitive impairment?
Extra symptoms include:
- Affecting daily life
- Difficulty in learning
- Difficult to complete familiar tasks
- Others are starting to notice changes in abilities
Is dementia more commonly caused by primary or secondary brain tumours?
Secondary (meaning metastases from other areas)
What kinds of trauma can cause dementia?
- Haematoma (particularly subdural)
- Post head injury (often years later)
- Chronic traumatic encephalopathy (common in pro athletes)
What toxins/deficiencies can cause dementia?
Toxins: alcohol, heavy metals, carbon monoxide
Deficiencies: Thiamine, B12
What infections can cause dementia?
- Syphilis
- HIV
Dementia diagnostic criteria
New, significant decline in:
- Learning and memory
- Language
- Executive function
- Complex attention
- Social skills
Must affect everyday life. Cannot exclusively occur during delirium, and should not be better accounted for by another disorder.
What is a big difference in presenting symptoms of vascular dementia vs Alzheimer’s?
- Alzheimer’s tends to involve memory loss
- Vascular dementia more often affects speed of thinking and problem solving (and can occur in the setting of a stroke)
What is the cholinergic hypothesis of AD?
AD shows substantial deficit in:
- Choline acetyltransferase (synthesis)
- Reduce choline uptake/release
- loss of cholinergic neurons from basal forebrain
We can treat dementia with cholinesterase inhibitors, but only symptomatically.
What factors influence our choice of diagnostic test in a patient with suspected Alzheimer’s?
- Education
- Culture
- Suspected stage of disease
- Logistical constraints
What diagnostic cognitive tests might we use in a patient with suspected Alzheimer’s?
- MMSE (good initially, but cannot detect subtle changes)
- Montreal cognitive assessment; MCS; (more detailed and more sensitive than MMSE)
- Clock drawing test (good for testing executive function, which may be affected in frontotemporal dementia)
- Alzheimer’s Disease Assessment Scale (ADAS): not commonly used due to length, but can be useful for detailed assessment
What medications might we give for dementia?
- Cholinesterase inhibitor (prevents breakdown of ACh)
- Memantine (NMDA receptor antagonist) {see if you can recall why…}
Why do we use memantine (an NMDA receptor antagonist) to treat dementia?
- NMDA are ionotropic glutamate receptors
- In dementia, glutamate can play a role in activating neuronal apoptosis, thus leading to neurodegeneration
- By inhibiting receptors, we inhibit degeneration. Big win.
Side effects of memantine
- Dizziness
- Confusion
- Drowziness
- Insomnia
- Agitation
Need to know underlying symptoms; otherwise, meds might literally make it worse.
Side effects of Cholinesterase inhibitors
- Diarrhoea
- Nausea/vomitingA
- Loss of appetite
- Sleep disturbance
(More ACh overactivates Parasympathetic Nervous System, leading to hypermotility which causes GI side effects)
Is current pharmacological management of dementia considered very effective?
No :(
