dementia Flashcards
definition of dementia
Neurodegenerative condition with progressive decline
Significant impairment of memory and one/more other cognitive (language, visuospatial skills and praxis) in a setting of clear consciousness, and interfering with work, social activities or relationships
subtypes of dementia
alzheimer’s
vascular
lewy body
fronto-temporal
vascular dementia
25%
Cumulative effect of many small strokes
sudden onset and stepwise deterioration is characteristic
look for evidence of arteriopathy (raised BP, past strokes, focal CNS signs)
lewy body dementia
15-25%
Fluctuating cognitive impairment
Detailed visual hallucinations
Parkinsonism
Histology is characterised by lewy bodies (eosinophilic intracytoplasmic inclusion bodies) in brainstem and neocortex
fronto-temporal dementia
Frontal and temporal atrophy with loss of >70% spindle neurons
Executive impairment
Behavioural/personality change
Disinhibition
Hyperorality
Stereotyped behaviour
Emotional unconcern
Episodic memory and spatial orientation are preserved until later stages
Pick’s disease – fronto-temporal dementia with Pick inclusion bodies on histology (spherical clusters of tau laden neurons)
epidemiology of dementia
- Prevalence increases with age, 20% >80yrs have it – only ½ cases diagnosed
aetiology of dementia
- Alzheimer’s disease
- Vascular – multiple infarctions
- Infection – HIV, syphilis, Whipple’s disease
- Inflammation – vasculitis, SLE, sarcoid, MS
- Trauma – heads injury, subdural haemorrhage
- Tumour – frontal tumour, posterior fossa (causing hydrocephalus), brain met, paraneoplastic
- Toxic – alcohol, lead, barbiturates, drugs
- Metabolic – myxoedema, vit b12 def, repeated hypoglycaemia
- Inherited – Wilson’s disease, Huntington’s chorea, cerebellar ataxias
- Degenerative – Parkinson’s and other akinetic-rigid syndromes, Pick’s disease, prion disease, lewy body dementia
- Pellagra
- CJD
- Cryptococcus
- Familial autosomal dominant Alzheimer’s
- CADASIL
sx of dementia
Memory loss over several years/mo
Ask about timeline of decline and the domains affected
Non-cog symptoms: agitation, aggression, apathy – indicate late disease
signs of dementia
- Cognitive testing
- Validated dementia screen eg AMTS or similar
- Tests of executive function or language
- Mental state examination to identify anxiety, depression or hallucinations
- Examination – may reveal physical cause, RF (eg for vascular dementia) or parkinsonism
- Medication review – exclude drug induced cognitive impairment
Ix for dementia
- Look for reversible/organic causes
- High TSH
- Low B12
- Low folate
- Low thiamine eg from alcohol
- Low Ca
- MSU
- FBC
- ESR
- UE
- LFT
- Glucose
- MRI
- functional imaging – FDG, PET, SPECT may delineate subtypes when diagnosis is not clear
- consider EEG
- If clinically indicated – checkautoAb, syphilis, HIV, CJD,
MRI for dementia
- identify reversible pathologies eg subdural haematoma, normal pressure hydrocephalus
- underlying vascular damage
- structural pathology
when would you do an EEG for dementia
- suspected delirium,
- frontotemporal dementia
- CJD
- Seizure disorder
definition of alzheimer’s
- Primary chronic progressive neurodegenerative dementia
- Characterised by extracellular deposition of B amyloid protein and intracellular neurofibrillary tangles
definition of mild cognitive impairment
impairment of some cognitive domains, insufficient to qualify for dementia diagnosis, or interfere with QOL
aetiology of alzheimer’s
- Unknown, most idiopathic.
- Rare – monogenic
RF for alzheimer’s
- age,
- prior intellectual level
- FH – 1st degree relative with AD
- Downs – AD is inevitable
- Homozygosity for apolipoprotein E E4 allele
- PICALM
- CL1&CLU variants
- Vascular RF – BP, dm, dyslipidaemia, high homocysteine, AF
- Low physical cognitive activity
- Depression
- Loneliness increases risk 2x
- Smoking
pathophysiology of alzheimer’s
Extracellular deposition of amyloid plaques containing B-42 peptides and intracellular accumulation of neurofibrillary tangles containing hyperphosphorylated Tau protein (microtubule protein)
B-amyloid is a degradation product of amyloid precursor protein
Causes progressive neuronal damage, neurofibullary tangles, increased number of amyloid plaques and loss of neurotransmitter Ach
Unclear which is causative pathology
Neurone count reduced in hippocampus, medial temporal and precuneate cortex
Vascular effects important
epidemiology of alzheimer’s disease
- Very common
- 5% people >65yrs
- Accounts for 60-80% dementias
- Diagnosis <60 rare
- Incidence increases exponentially with age
sx of alzheimer’s
Reliable history from relative
Gradual deterioration of cog func
- Initially antegrade amnesia, personality change, apathy, loss of concentration and disorientation. May have psychiatric manifestations – hallucinations and delusions
- Language spared until late
- Late stages – cog impairment in all domains: (memory, language, visuospatial), myoclonus, seizures, behavioural disturbances (irritability, mood disturbance eg depression/euphoria, behavioural change eg aggression/wandering/disinhibition, psycosis ie hallucinations/delusions, agnosia – don’t recognise self, incontinence and loss of independence
Non-cognitive symptoms come and go over months
Suspect in pts: >40, with persistent progressive and global cognitive impairment (visio-spatial skill, memory, verbal abilities, executive func)
Anosognosia – lack insight into problems caused by the disease: missed appointments, misunderstood conversations or plots of films, mishandeling of money
Eventually sedentary – little interest in anything
signs of alzheimer’s
Mini-mental state exam (MMSE) screening tool (<27 = dementia)
Premorbid intellectual function needs to be considered
In amnestic alzheimers – delayed recall is impaired even with prompting
Ix for alzheimer’s
- Aimed at excluding treatable causes of dementia
- Blood
- CT/MRI brain
- psychometric testing
- EEG
- LP
- nuclear imaging
bloods for alzheimer’s
- FBC,
- UE,
- LFT,
- ESR,
- CRP,
- TFT (exclude hypothyroid),
- folate,
- ANA,
- ANCA,
- vitamin B12,
- treponemal serology.
- Consider HIV serology
CT/MRI for alzheimer’s
- Cerebral/hippocampal atrophy
- Exclude tumours, infarction, inflamm, subdural haematoma
psychometric testing for alzheimer’s
- Defining domains of impairment
- Helpful for distinguishing depressive pseudo-dementia
