236 - Dementia

Question 1

what is the diagnostic criteria for dementia?

Answer 1

acquired memory impairment for at least 6m plus impairment in one or more cognitive domains:

• executive functioning - abstract thinking, judge, reason
• language - expressive and receptive
• praxis - learned motor tasks
• gnosis - ability to recognise objects, faces, sensory info

Question 2

what is the prevalence of dementia?

Answer 2

5% of >65s but 22% of 85-90 - 20 million worldwide

Question 3

name some differentials for dementia?

Answer 3

• depression - low mood, worthlessness, guilt, suicide, anhedonia, appetite change, sleep disturb, fatigue, conc - also pseudodementia (aware of memory loss)
• delirium - acute confusion sudden onset and fluctuating. associated with physical illness (infection, drugs, alcohol)
• vitamin deficiency. vit B1 (thiamine) >wernickes, B12, folate
• hypothyroidism - depression
• hepatic/renal impairment
• normal pressure hydrocephalus -abnormal CSF resorption - enlargement of ventricles and compression

Question 4

what is the difference between dementia and mild cognitive impairment?

Answer 4

does not interfere with activities of daily living

Question 5

who does alzheimers affect?

Answer 5

• > 50% of dementias
• > 70s and more females 2:1
• family hx - apolipoproteins E-4 allele and Presenilin
• down’s syndrome
• head injuries

Question 6

what is thought to cause alzeimers?

Answer 6

• neurofibrillary tangles - changes to Tau proteins that act as glue to hold neuron microfobrils together
• senile plaques - extracellular deposits of amyloid in grey matter between neurons or cerebral blood vessel walls. Especially in hippocampus (memory area)
• cerebral cortex atrophy - association regions and medial temporal lobe
• overactivation of NMDA receptors by glutamate. deficiencies in reuptake by astroglial cells in synaptic cleft
• leads to cholinergic dysfunction and cholinergic input to hippocampus and amigdala from basal forebrain

Question 7

what is the difference between alzheimers and vascular dementia?

Answer 7

• AD - dementia with insidious onset and progressive gradual decline.
• VD - Abrupt onset, stepwise deterioration, fluctuating cognitive performance, gait and incontinence, neuro signs (focal deficits/stroke), evidence of vascular disease on brain imaging

Question 8

who does vascular dementia affect and what causes it?

Answer 8

• 20-25% of dementias
• > 60s, more male than female, hypertensives and those with cardiovascular risk factors
• either focal (2ndry to thrombtic or embolic vascular occlusion - affects white matter or cerebrum and deep grey nuclei of thalamus and striatum) r difuse (2ndry to HTN or stenosis of vessels)

Question 9

what is dementia with Lewy bodies?

Answer 9

• 10-15% of dementias
• Lewy bodies are intracellular aggregates of alpha-synuclein protein causing disruption to dopaminergic and cholinergic systems of brain
• criteria - dementia plus one of: visual hallucinations, parkinsonism, reduced alertness plus one of: REM behaviour disorder or non specific neuro signs. If symptoms soon after parkonism then DLB

Question 10

what is fronto-temporal dementia?

Answer 10

• picks disease
• fronto-temporal atrophy
• early onset, more males, behavioural changes (personality and inappropriate behaviour), loss of speech with memory and skills intact, FH

Question 11

how could a patient with dementia be assesed?

Answer 11

*mini mental exams
- Addenbrookes Cognitive Exam (ACE III)
- Montreal Cognitive Assessment (MoCA)
6 item CIT (Kingshill)
*Clock drawing test
*CT to exclude other path
*MRI - regional atrophy and cerebrovascular disease

Question 12

how would you manage mild to mod alzheimers and DLB?

Answer 12

• Aceytlcholinesterase Inhibitors eg donepezil, rivastigimine, galantamine
• inhibit ACh breakdown and incr conc in synaptic cleft
• gastric irritation and ulceration, bradycardia, epilespy, asthma, prostatism

Question 13

how would you manage advanced alzeimers or mild AD when unresponsive to ACh-esterase?

Answer 13

• NMDA receptor antagonists eg memantine

* inhibits glutamate by blocking NMDA receptors - reduces glutamate’s excitotoxic effects

Question 14

how would you treat vascular dementia?

Answer 14

aspirin, statin, BP management and glucose management, lifestyle change

Question 15

what is neurodegeneration and what causes it?

Answer 15

• chronic, progressive neuronal loss
• genes and toxins by:
• apoptosis
• autophagia
• necrosis by:
• infarction, neuroinflammation
• misfolded proteins > plaques and hyperphosphrylated Tau (tangles)
• oxidative stress
• glutamate release after cell death> cycle

Question 16

what types of memory are there?

Answer 16

• short term memory
• long term memory - short term made perm
• working memory - held for mins to complete task
• declarative (explicit) - semantic memories (concepts) and episodic (autobiographical) - stored in medial temp lobe, thalamus and hypothalamus
• non-declarative (implicit) - procedural memory/skills/habits in striatum, motor learning in cerebellum and emotional conditioning in the amygdala

Question 17

what types of amnesia are there?

Answer 17

• retrograde
• anterograde
• transient global amnesia - both retro and antero

Question 18

how is memory created?

Answer 18

sensory input > cortical association areas (identify stimulus, make sense and plan) > parahippocampal /rhinal cortices (storage of long term memory > hippocampus (consolidation of short term/working memory into long term) > mamilary bodies (hypothalamus) and thalamus (recognition, smell, emotion)

Question 19

what do the hippocampus and amygdala do?

Answer 19

• hippocampus - learning of newinfo, consolidation to long term memory with cortex communication, place memory
• amygdala - emotional info learning and its consolidation

Question 20

what is affected in korsakoffs syndrome

Answer 20

• irreversible damage to medial thalamus and maillary bodies - caused by thiamine (vit B1) deficiency - may also cauuse Wernickes encephalopathy
• causes antero/retrograde amnesia and cofabulation (cannot distinuish between imagination and memory)

Question 21

what does each lobe of the brain do?

Answer 21

• occipital - visual cortex
• parietal - attending to stimuli (where is it)
• temporal - identify nature of stimuli (what is it)
• frontal - planning appropriate response (what should I do about it)

Question 22

what is the parietal cortex responisible for?

Answer 22

• integration of visual, auditory and somatosensory information
• damage causes sensory neglect, conceptual neglect, motor neglect and hemiasomatognosia (denial that part of body is theirs) on contralateral side of body

Question 23

what is apraxia/

Answer 23

inability to carry out a motor task in response to a spoken command

Question 24

what is the temporal cortex responsible for?

Answer 24

• identifying nature of stimuli
• damage causes agnosia (loss of knowledge)
• inf temp cortex - visual agnosia (cant identify objects)
• fusiform gyrus (med temp occipital) - prosopagnosis (cant identify faces)
• middle temp cortex - movement agnosia (cant tell between stationary and moving)

Question 25

what is the frontal cortex responsible for?

Answer 25

• mediates behaviour - restraint, intiative and order
• damage causes inability to plan sequence of events, loss of thought flexibilty, perservation, loss of focus, passivity, apathy, expressive aphasia

Question 26

what are wernickes and brocas areas responsible for/

Answer 26

• wernickes- understanding speech

* brocas - makes speech

Question 27

what are wernickes and brocas aphasia?

Answer 27

• wernickes - inability to understand language - fluent speech but makes no sense (little repetition but good syntax and grammar)
• brocas - ability to understand language but inability to produce own halting speech - repetitive, disordered syntax and grammar