Dementia Flashcards
What are the different categories of dementia?
Dementia is a complex syndrome with many causes. There are specific genes and molecular mechanisms that underlie Alzheimer’s disease however is complicated because there’s not one single cause that contributes to disease and because the symptoms of the disease only become obvious after the underlying pathology has progressed it’s difficult to have effective treatment for it
Alzheimer’s disease is the main cause of dementia 60% of patients. It is a physical condition caused by changes in the structure of the brain. This is due to a build-up of proteins, resulting in ‘plaques’ and ‘tangles’ which damage the brain cells’ ability to transmit electrical impulses and communicate with the body and eventually lead to brain cell death.
Vascular dementia accounts for 20% of patients.
Vascular dementia is the second most common type of dementia. It is caused by problems in the supply of blood to the brain cells, commonly due to strokes or a series of small strokes, known as Transient Ischaemic Attacks (TIAs), which cause areas of localised cell damage in the brain.
Dementia with Lewy bodies affects movement and motor control. The patient could have tremors which are also seen in Parkinson’s disease.
5% is due to frontotemporal dementia- can often be missed for the first 5 years of the syndrome but affects personality and speech.
What is Alzheimer’s disease?
Alzheimer’s disease is the most common form of progressive senile dementia primarily affecting individuals over the age of 65.
Familial Alzheimer’s disease can result in early onset (30-60 years).
The disease leads to the inevitable destruction of neurons, and ultimately death within 7 to 10 years.
Alzheimer’s is not “normal aging”.
What Alzheimer’s risk factors are there?
Risk factors include:
Advanced age
Genetic: (3-5% of cases?) Down’s syndrome (chromosome 21); presenilins (14, 1) and ApoE4 (19)
Cerebral perfusion
Head trauma
Female (1.4: 1)
Environmental
What happens in Alzheimer’s disease?
Alzheimer’s disease is associated with brain shrinkage and loss of neurons in many brain regions. Several areas of the brain are at risk and this is why there is such a wide range of symptoms and effects on the patients. the loss of cholinergic neurons in the hippocampus and frontal cortex is a feature of the disease and is thought to underlie the cognitive defect and the loss of short term memory that occurs.
What does the cerebral cortex do?
Involved in conscious thought and language.
What does the basal forebrain do?
Important in memory and learning
What does the hippocampus do?
essential to memory storage
What happens in the brain in AD?
The exact cause is unknown but we do know that ‘plaques’ and ‘tangles’ form in the brain due to two proteins called amyloid (plaques) and tau (tangles).
Amyloid protein is found in the brain when B secretase enzyme cleaves the amyloid protein it forms β amyloid which is more sticky compared to normal amyloid protein.
Results in a Build up of amyloid plaques
If the amyloid plaques form outside neurons
it get between neurons and prevents communication with memmory neurons resulting in memory loss.
This results in an inflammatory response - the increased inflamation and inflammation markers build up in blood vessels which weakens them and results in blood leakage
If the amyloid plaques are inside neurons.
Tau protein is inside the neurons
amyloid plaques activates kinase in the cell causing tau proteins to become tangled together = apoptosis
Cells die = atrophy shrinkage of the brain and an increase in ventricle size
synaptic loss is the principal correlate of disease progression and loss of cholinergic neurons contributes to memory and attention deficits
What is the amyloid hypothesis?
Cause of degeneration
The exact cause is unknown but we do know that ‘plaques’ and ‘tangles’ form in the brain due to two proteins called amyloid (plaques) and tau (tangles).
Amyloid is a naturally occurring protein which for a reason that is not yet understoodbegins to malfunction, creating beta amyloid which is toxic to the brain cells. Plaques form consisting of dead cells and amyloid protein.
Mutations of the Apolipoprotein E4 (ApoE4) enhance aggregation of β amyloid. ApoE is involved in transport and delivery of cholesterol to cell surface apoE receptors.
Tau protein naturally occurs in the brain and helps brain cells communicate with each other but for a reason that is not yet understoodit can become abnormal and “clump together” leading to death of the brain cells affected.
What is dementia?
Decline in cognitive ability, the decline is caused by cell loss. Syndrome rather than a disease, effects elderly people.
The Alzheimer’s brain is associated with loss of memory BECAUSE plaques and tangles build up leading to cell death.
A. Both the assertion and the reason are true statements, and the reason is a correct explanation of the assertion.
B. Both the assertion and the reason are true statements, but the reason is not a correct explanation of the assertion.
C. The assertion is true, but the reason is false.
D. The assertion is false, but the reason is in fact a true statement in its own right.
E. Both the assertion and reason are false.
A
What effect does β amyloid plaques have on the brain?
B amyloid plaques have on brain?
Plaques block the synapses slowing down electrical impulses not getting same communication lead to memory loss. On neurons stops communication and if it’s in neurons activate kinase which causes tou protein to tangle together.
How is dementia diagnosed?
GP will take a medical and family history of the person, and will screen them for mental health and cognitive issues by: asking questions, testing concentration, short term memory, mood and behaviour changes.
MMSE it includes tests of orientation, attention, memory, language and visual-spatial skills.
Early diagnosis is important and there are advantages to starting treatment early.
Clinical criteria
Cognitive testing: Mini-Mental State Examination (MMSE)
21-24 points mild dementia
10-20 points moderate dementia
Lab test dependent on history and clinical circumstances - Lab tests can rule out delirium caused by a infection or an underactive thyroid
The GP may then request blood tests, an MRI or CT scan to examine the structure of the brain, or request a chest X-ray to check for any chest conditions.
Exclusion of depression
Use of imaging:
MRI for early diagnosis and diagnosis of vascular or frontotemporal dementia
SPECT to differentiate subtypes – Lewy body dementia - SPECT- imaging technique uses a tracer to determine blood flow to specific areas–
Initial Assessment (2-3 months)
Advantages of MMSE?
This test is Relatively quick and easy to perform and can provide a method of monitoring deterioration over time
Disadvantage of MMSE
The disadvantage of this test is it had Poor sensitivity at detected mild/early dementia
