Dementia Flashcards
what is the prevalence of dementia in different age groups?
- VERY RARE <55 YEARS
- 5-10% PREVALENCE IN >65’S
- 20% IN >80 YEARS
- 80% IN >100 YEARS
what are the primary dementias?
ALZHEIMER’S DISEASE (60-75%)
LEWY BODY DEMENTIA (10-15%)
PICK’S DISEASE (FRONTO-TEMPORAL DEMENTIA) (<2%)
HUNTINGTON’S DISEASE
what are the secondary dementias?
- MULTI-INFARCT (VASCULAR) DEMENTIA (20%)
- INFECTION (HIV, SYPHILIS)
- TRAUMA
- METABOLIC
- DRUGS AND TOXINS (ALCOHOL)
- VITAMIN DEFICIENCIES (VITAMIN B1)
- PARANEOPLASTIC SYNDROMES
- INTRACRANIAL SPACE OCCUPYING LESIONS
- CHRONIC HYDROCEPHALUS
what are the macroscopic features of Alzheimer’s?
o Decreased size and weight of brain (cortical atrophy)
o Location: frontal, temporal and parietal lobe atrophy
o Widening of sulci
o Narrowing of gyri
o Compensatory dilatation ventricles, 2° hydrocephalus ex vacuo
o Occipital lobe spared, brainstem and cerebellum normal
what are the microscopic features of Alzheimer’s?
Extensive neuronal loss with associated astrocyte proliferation - simple neuronal atrophy, gliosis
Neurofibrillary tangles
Neurotic Plaques
Amyloid Angiopathy
what are neurofibrillary tangles made of?
Tau protein associated with microtubules
where are neurofibrillary tangles found?
hippocampus and temporal lobe
Intracytoplasmic
what are neuritic plaques made of?
Aß amyloid plaques (dense amyloid oligomers)
where are neuritic plaques found?
Surrounding astrocytes and microglia
Found in hippocampus and parietal lobes
how are neuritic plaques?
excess intraneuronal amyloid peptides, due to overproduction or diminished clearance of beta-amyloid.
cause an inflammatory process through microglial activation, cytokine formation, and activation of the complement cascade. Inflammation leads to the formation of neurotic plaques, causing synaptic and neurotic injury and cell death.
what is amyloid angiopathy?
Polymerised beta pleated sheets formed by AB
leads to Extracellular eosinophillic accumulation
what is the consequence of amyloid angiopathy?
Disrupts blood brain barrier: • Serum leaking • Oedema • Local hypoxia • exacerbating oxidative stress, excitotoxicity and neuronal injury
what are the causes of Alzhemier’s?
Sporadic
Familial - point mutation of apolipoprotein E – allele e4, Presenilin 1 – Chromosome 14 and Presenilin 2 – Chromosome 1
Trisomy 21
what are the risk factors to Alzhemier’s?
o smoking o midlife obesity o insulin resistance o diet high in saturated fats o ???increased serum cholesterol and homocysteine levels, vitamin e and vitamin C
What is the summary steps of Alzheimer’s?
Abnormal production of AB results in AB oligomerisation and formation of plaques
which cause astrocyte, microglial activation, and possibly directly to excitotoxicity….
Main lesion = Abeta oligomer, they enter synaptic space and cause excitotoxicity = Ca2+ influx, mitochondrial dysregulation and cell death
Oligomers also cause Tau hyper-phosphorylation and mislocalisation of Tau which enhances the excitotoxicity affect of Abeta oligomers
what are the clinical features of Alzheimer’s?
- Insidious impairment of higher intellectual function
- gradual, progressive onset
- memory loss – affects short term memory more than autobiographical and political
- language deficits
- nominal dysphagia
- apathy
- with alterations in mood and behaviour
- decline in ADLs
what are the late clinical features of Alzheimers?
Progressive disorientation, memory loss and aphasia = severe cortical dysfunction
• Can result in profound disability, muteness and immobility
What are the initial investigations for Alzheimer’s?
Cognitive testing
CT and MRI
Biochemical tests
Amyloid-PET
what are the biochemical tests for Alzheimer’s?
FBC, metabolic panel, serum TSH, serum Vit-B12, urine drug screen, neuropsychological testing, serum RPR/VDRL, serum HIV, CSF analysis, egnetic testing, FDG-PET, SPECT, electroencephalogram
what is the main management of Alzheimer’s?
- supportive treatment – OT and support groups
* cholinesterase inhibitors – donepezil, rivastigmine, rivastigmine transdermal, galantamine
what is the additional management of Alzheimer’s?
o antidepressants – sertraline, citalopram, escitalopram, mirtazapine, trazodone
o antipsychotics – risperidone, olanzapine, quetiapine, aripiprazole, haloperidol, ziprasidone
o management of insomnia
o behavioural modification – citalopram, carbamazepine, lorazepam, trazodone
o Switch to or add Memantine if severe of cholinesterase inhibitors not effective
what are the complications of Alzheimer’s?
Death usually occurs due to a secondary cause – like bronchopneumonia
what is the characteristic feature of Lewy body dementia?
accumulation of Lewy bodies
what are Lewy Bodies composed of?
alpha-synuclein
what is the mechanism of Lewy Body damage in LB dementia?
synuclein aggregates = insoluble -> cell dysfunction -> cell damage, leads to disruption of cholinergic and dopaminergic pathways
what part of the brain is affected in LB dementia?
degeneration of the substantia nigra
what are the macroscopic features of LB dementia?
pallor in the substantia nigra, where pigmented dopaminergic neurons run
what are the microscopic features of LB dementia?
o Loss of pigmented neurons
o Reactive gliosis, microglial accumulation
o Remaining neurons may show Lewy bodies:
o Fewer cortical Lewy bodies
what are the microscopic features of lewy bodies in neurons?
“Single / multiple intracytoplasmic, eosinophilic, round to elongated bodies that have a dense core and a surrounding pale halo”
Aggregates of a-synuclein and ubiquitin
what are the causes of lewy body dementia?
- unknown
- most sporadic
- some familial clusters - alpha-synuclein gene on chromosome 4, and apolipoprotein E e4 allele.
what are the clinical features of lewy body dementia?
- progressive dementia
- hallucinations
- fluctuating levels of attention/cognition
- memory affected later than AZ
- parkinsons features
- REM sleep disturbance
what are the additional clinical features of lewy body dementia?
depression, falls + syncope, orthostatic hypotension, urinary incontinence + constipation, delusions, hypersomnia, hyposmia
what is the association between Parkinson’s and LB Dementia?
Everyone with lewy body dementia will get parkinsonism, Not everyone with Parkinson’s disease get Lewy body dementia
how is LB dementia diagnosed?
Cognitive testing
CT and MRI
Biochemical Investigations
Amyloid PET
what is the management of LB dementia?
Cholinesterase Inhibitors – donepezil, rivastigmine, rivastigmine transdermal, galantamine