2.12 - Dementia Flashcards
What is the commonest cause of dementia?
Alzheimer’s disease
What is Alzheimer’s disease?
A fatal neurodegenerative disorder characterised by progressive cognitive, social and functional impairment
Is there a cure for Alzheimer’s?
No current cure, with acetylcholinesterase inhibitors having modest symptomatic benefit in early stages
What is the difference in prevalence of causes of dementia in young onset dementia (YOD) sufferers vs late onset dementia (LOD) sufferers?
- Alzheimer’s disease is the most common cause in both, but way bigger proportion in LOD
- YOD sufferers have slightly more prevalence of familial autosomal dominant Alzheimer’s (fAD)
- Lewy body dementia, frontotemporal dementia and other causes are more common in YOD
What are the four most common causes of dementia?
- Alzheimer’s disease
- vascular dementia
- frontotemporal dementia
- dementia with Lewy bodies
What are some other potentially reversible causes of dementia? (9)
- depression
- alcohol related brain damage
- endocrine e.g. hypothyroidism, Cushing’s, Addison’s
- B1/B12/B6 deficiency
- benign tumours
- normal pressure hydrocephalus
- limbic encephalitis
- infections - HIV/syphilis, Whipple’s disease
- inflammatory
What does the continuum of dementia look like?
- in normal ageing - as years increase, cognitive function gradually decreases
- in dementia - as years increase, cognitive function decreases more steeply and eventually reaches zero
- the phases of dementia are preclinical (deterioration in function without clinical features) –> mild cognitive impairment –> dementia
What does the continuum of dementia look like in reality and why?
Many ups and downs in cognitive function over time but with a general decreasing trend - small ups and downs can be due to changes in eating and drinking, sleep, infection etc
Why is it difficult to diagnose dementia in clinic?
- the disease follows a heterogenous course
- in old age the disease presentation is of multiple comorbidities
- lots of mixed and uncertain pictures
- younger patients are more typical
What is the most important thing for doctors to do in clinic with dementia patients?
- get a clinical history
- see how well the patient is functioning
- how they change
What physiological issues may be present in the brain of those with dementia?
- A-beta
- TDP-43
- alpha-synuclein
- neuronal tau
- parenchymal ischaemic changes
- vessel wall pathology e.g. cerebral amyloid angiopathy
What is the path a dementia patient takes through NHS?
- referral (e.g. by GP/psychiatrist)
- history (with clinical interview)
- examination
- investigations
- diagnosis
- management
What things do we ask/check during the interview with dementia patients?
- memory
- language
- numerical skills
- executive skills
- visuospatial skills
- neglect phenomena
- visual perception
- route finding and landmark identification
- personality and social conduct
- sexual behaviour
- eating
- mood
- motivation/apathy
- anxiety/agitation
- delusions/hallucinations
- activities of daily living
- do a collateral with children of sufferer
- look at chronology of each and how symptoms have changed over time
Define dementia?
Severe loss of memory and other cognitive abilities which leads to impaired daily function (regardless of the underlying cause)
What examinations happen after the interview for dementia?
- neurological - cranial nerves, upper and lower limb nerve test
- mental state e.g. speech, mood, behaviour, perception
What investigations are done after the examination for dementia?
- neuropsychology - MMSE, ACE III, MoCA
- bloods
- MRI
- PET
What bloods are taken as part of the investigation for dementia?
- full blood count
- inflammatory markers
- thyroid function
- biochemistry and renal function
- glucose
- B12 and folate
- clotting
- syphilis serology
- HIV
- caeruloplasmin
What do you see on a sMRI as Alzheimer’s progresses?
- narrowed sulci
- widened gyri
- dilated and enlarged ventricles
- medial temporal volume loss
- bilateral hippocampal volume loss
- shrunken structures that are replaced by CSF, therefore appearing black
What do PET scans for dementia involve?
Cannulating patient, injecting them with contrast, travels to brain and lights up amyloid in brain, amyloid and tau are pathognomic for Alzheimer’s
What PET scan signs are pathognomonic of Alzheimer’s disease?
Amyloid along with Tau proteins
What are the common potential diagnoses that can be made related to dementia? (7)
- Alzheimer’s
- vascular
- Lewy body
- frontotemporal
- depression
- delirium
- none
What are the potential management strategies for dementia? (5)
- acetylcholinesterase inhibitors (AD)
- watch and wait (to see how current condition changes)
- treat behavioural/psychological symptoms
- OT/social services
- specialist therapies
What signs could you use to identify Alzheimer’s? (3)
- subtle
- insidious amnesia
- insidious non-amnestic presentations
What signs could you use to identify vascular dementia?
- related to cerebrovascular diseases with step-wise deterioration
- multiple infarcts i.e. strokes
What signs could you use to identify dementia with Lewy bodies?
- cognitive impairment before/within 1 year of Parkinsonian symptoms
- visual hallucinations and fluctuating cognition
What signs could you use to identify frontotemporal dementia?
- behaviour variant FTD
- semantic dementia
- progressive non-fluent aphasia
What is episodic memory (AD)?
- memory for particular episodes in life
- dependent on medial temporal lobes, including the hippocampus
When can diagnosis of Alzheimer’s be made certain?
Only be made certain at post-mortem - diagnosis in life was only probable until recently
What are some biomarker patterns in Alzheimer’s? (4)
- primary event - A-beta amyloid
- Tau proteins
- changes to brain structure
- cognition lag
How is a lumbar puncture used in the diagnosis of Alzheimer’s?
To obtain CSF and see how much amyloid and tau proteins there are
What does Alzheimer’s disease typically involve?
Initial episodic memory deficits secondary to dysfunction of medial temporal lobe structures (entorhinal cortex and hippocampus)
What happens in dementia with Lewy bodies? (6)
- associated with fluctuating cognition
- different cognitive profile to AD
- often visual hallucinations
- REM sleep disorder
- development of symptoms associated with Parkinson’s disease
- high risk of falls
What is the pathophysiology of dementia with Lewy bodies?
Aggregation of alpha synuclein –> deposition of Lewy bodies –> symptoms (Lewy bodies in glial cells = myelin and glial dysfunction and subsequent neuronal degeneration)
(Cerebral atrophy, particularly of the frontal lobe with relative sparing of the hippocampi)
How does the MRI scan in dementia with Lewy bodies compare to that in AD?
MRI shows that unlike Alzheimer’s, hippocampal volume and medial temporal lobe volume generally preserved
How does the PET scan in dementia with Lewy bodies compare to that in AD?
- AD - caudate and putamen lit up, lots of dopamine transporters available
- LBD - less lit up due to less available dopamine transporters (less dopamine –> Parkinsonian symptoms) - characteristic of LBD
What do patients with frontotemporal dementia present with? (3)
- increasing behavioural disturbance
- agitation
- reduced speech output
What does an MRI for frontotemporal dementia show?
- extensive volume loss in temporal lobes and frontal opercula, more so on right
- Perisylvian fissure volume loss
What is vascular dementia?
- infarction of small and medium-sized vessels (essentially mini-strokes)
- neuronal death —> location specific deficits —> step-wise deterioration
- symptoms reflect area of infarction:
- frontal - executive dysfunction, judgement, DM
- temporal - anterograde amnesia
- parietal - aphasia, agnosia, apraxia, confusion, agitation
