Dementia Flashcards
Give four main types of Dementia disorders
- Alzheimer’s disease
- Dementia with Lewy bodies
- Frontotemporal dementia
- Vascular dementia
How does Alzheimer’s dementia present?
what is the biological cause?
- Gradual onset of impaired memory, planning and functional skills
- due to degeneration of the cerebral cortex, with cortical atrophy, neurofibrillary tangles, amyloid formation and reduction in acetylcholine
What are the two ways to look at the Neuropathlogically presentations of dementia
- Microscopically
- Intra neuronal inclusion bodies
- Extra neuronal changes (plaques)
- Macroscopically
- Generalised brain atrophy
- Region specific atrophy depending on dementia disorder
- Enlarged ventricles
Give some microscopic causes of Dementia
- Misfolding of proteins
- Abnormal accumulation
- Neuroinflammatory environment
- Damaged neurons
- Cell death
- Damaged neurons
- Proteins involved:
- Amyloid
- Tau
- Synuclein
What dementia disease is caused by Tau abnormalities?
- Alzheimer’s disease
- can also be caused by Amyloid abnormalities
- Frontotemporal dementia
What is Tau?
- a highly soluble protein found mostly in the brain
- it is mostly present in axons
- it has 6 isoforms and disease process lead to hyperphosphorylated forms of the protein
Functions
- modulate the stability of axonal microtubules
- transport
Abnormalities in Tau
Hyperphosphorylated forms of Tau
- Paired helical filaments (PHF)
- Neurofibrillary tangles (NFTs)
- PHFs –> NFTs –> Neurodegeneration
- Phosphorylation of tau is regulated by activated kinases
- Hyperphosphorylation of tau can result in the self-assembly of tangles of paired helical filaments (PHF).
Explain Neurofibrillary tangles
Described by Alois Alzheimer: consist of paired 10-nanometer diameter filaments twisted around each other in a helical manner (paired helical filaments HF)
- Seen in neurons after staining
- Hematoxylin
- Eosin
- Bielschowsky
- Bodian
- Congo red
- Most commonly found in temporal lobe structures
- Hippocampus
- Amygdala
Amyloid Precursor Protein (APP) in normal and diseased brains
- APP is a transmembrane glycoprotein which is broken down and eliminated in normal brain
- APP is split by enzymes ß-secretase then y-secretase.
- ß-amyloid is a peptide of 39–43 amino acids
- Most common isoforms are Aβ40 and Aβ42
- Aβ40 is more common of the two, but Aβ42 is the more fibrillogenic and is thus associated with disease states.
- Fragments accumulate to form plaques, the build-up of ß-amyloid plaques cause neuronal damage
Frontotemporal Dementia (FTD)
- Tau pathology, Pick’s disease described by Arnold Pick 1892
- Pick bodies
- rounded, microscopic structures found within neurons
- Aggregates of tau
- Hirano bodies
- Neurons swell, taking on a “ballooned” appearance. Hence, called balloon cells.
- Plaques and tangles are not found in Pick’s disease.
- FTD is present in frontal and anterior temporal lobes.
What is the presentation of Frontotemporal dementia?
- Typical symptoms include changes in personality and behaviour (disinhibition) and difficulty in language
- Usually, develop at a younger age (60y)
What are Synuclein abnormalities?
- Parkinson disease
- Dementia with Lewy bodies
- Fibrillary aggregates of alpha-synuclein protein
What are Synuclein?
- Small, presynaptic neuronal proteins comprised of α-, β-, γ-synucleins of which only α-synuclein aggregates
- Proteins of 140 amino acids, that is expressed predominantly in neurons
- Found in neurons and glial cells
- Function as lipid vesicle binding, inhibition of phospholipase D2 and protein kinase C, dopamine uptake and as a chaperone have been ascribed to α-synuclein.
- Predominantly expressed in neocortex, hippocampus, substantia nigra and cerebellum.
- Can aggregate to form intracytoplasmic inclusions in neurons (Lewy bodies).
What are Lewy bodies?
- Spherical, intranuclear, cytoplasmic eosinophilic inclusions
- Abnormally truncated and phosphorylated neurofilament proteins
- Contain:
- Alpha-synuclein
- Ubiquitin
- Associated enzymes.
What is the cause of Vascular dementia and its presentation
- Due to cerebrovascular disease (1 large stroke or small multi-infarcts)
- stepwise decline presents similarly to Alzheimer’s disease initially but patients often have more insight
What is the presentation of Dementia with Lewy bodies?
- a triad of C_ognitive fluctuation_, Vivid visual hallucinations and Parkinsonism
- this is due to Lewy body deposition
Vascular dementia
- Can result from ischemic or hemorrhagic brain damage.
- The three most common mechanisms causing disease
- Single, strategically placed infarcts
- multiple cortical infarcts
- subcortical small-vessel disease.
- Clinical deficits are determined by the size, location, and type of cerebral damage.
- Because of the variety of pathogenic mechanisms involved in vascular dementia, clinical manifestations can vary.
What steps need to be taking to reach a diagnostic conclusion of a Dementia disease?
- History
- Examination
- Bloods/ECG
- Neuropsychological
- Behavioural/Activities of Daily Living
- Neuroimaging
What examinations are done when Dementia is a differential diagnosis?
- General examination
- Neurological examination
- Mental State Examination
What bloods/ ECG would be taken for a neurological consultation?
- FBC
- ESR
- U/Es
- LFT
- TFT
- B12/folate
- Syphilis serology
- ECG
What Imaging can be done during a neurologic consultation?
- CT
- MRI
- SPECT
- PET
What treatment can be given for Alzheimer’s dementia?
- Donepezil,
- Rivastigmine,
- Galantamine,
- Memantine
What treatment can be given for Vascular Dementia
- Identify & Treat vascular risk factors
- Hypertension
- Diabetes
- Hyperlipidaemia
- AF
- Carotid disease
- put patients on anticoagulants
Treatment for Frontotemporal dementia
- SSRI antidepressants