B&B Week 8 Flashcards
what circuit of structures is responsible for recent memory (aka declarative or episodic memory)?
papez circuit
hippocampal formation–> fornix–> mammillary body–> mamillothalamic tract–> anterior group of the thalamus–> cingulate gyrus –> cingulate bundle –> hippocampal formation once again
what is the critical structure in the papez circuit?
hippocampus (the most medial part of the temporal lobe)
what type of material specific amnestic syndromes will be produced if there is a lesion in the papez circuit in the dominant hemisphere?
verbal memory disturbance
what type of material specific amnestic syndromes will be produced if there is a lesion in the papez circuit in the non-dominant hemisphere?
non-verbal memory disturbance
what are the symptoms of an amnestic syndrome?
- anterograde amnesia
- varying degrees of retrograde amnesia
- preserved very remote memory (i.e long term, semantic memory)
- intact attention
- intact non-mnemonic intellectual functions (i.e calculation, visuospatial ability
how do you test cognitive intellectual function?
- initial assessment–> alert? oriented?
- regional cortical function–> assess vision, motor, hearing, sensation, language
- complex integrated response–> assess ability to complete 2 and 3 step processes (fist, side, flat hand motions)
- CIF–> assess attention (digit span, serial 7s, A test which is raising your hand every time you hear the letter A); assess mnemonic and nonmnemonic cognitive intellectual capacities
doubling/serial 7s…
- what neuroanatomical area is being tested with this test?
- what cognitive function is being tested with this test?
- what hemisphere (dominant or nondominant) is being tested with this test?
- heteromodal complex
- calculation
- dominant
3 word repeat…
- what neuroanatomical area is being tested with this test?
- what cognitive function is being tested with this test?
- what hemisphere (dominant or nondominant) is being tested with this test?
- temporal lobe, recent memory processor
- GFK, semantic memory (verbal memory)
- dominant hemisphere
3 shape repeat…
- what neuroanatomical area is being tested with this test?
- what cognitive function is being tested with this test?
- what hemisphere (dominant or nondominant) is being tested with this test?
- temporal lobe, recent memory processor
- GFK, non verbal memory
- non-dominant
3D cube drawing…
- what neuroanatomical area is being tested with this test?
- what cognitive function is being tested with this test?
- what hemisphere (dominant or nondominant) is being tested with this test?
- heteromodal complex
- visual-spatial processor
- non-dominant
in the dominant hemisphere, what does the parietal lobe do in terms of cognitive function? what does the temporal lobe do?
dominant hemisphere:
parietal lobe–> calculation
temporal lobe–> GFK/semantic (verbal) memory
in the non-dominant hemisphere, what does the parietal lobe do in terms of cognitive function? what does the temporal lobe do?
non-dominant hemisphere:
parietal lobe–> visual spatial
temporal lobe–> nonverbal memory
what are the 3 types of memory based on time?
- sensory memory–> less than 1 sec
- short term memory/working memory–> less than 1 min
- long term memory–> lifetime
what are the types of long term memory?
- EXPLICIT memory (conscious) –> declarative memory (facts, events)–> episodic memory (events ,experiences)//semantic memory (facts, concepts)
- IMPLICIT memory (unconscious) –> procedural memory (skills, tasks)
what are the two types of declarative memory (which is a subtype of explicit memory)?
episodic (events, experiences)
semantic (facts, concepts)
what are cognitive-intellectual functions?
higher levels of information processing (attend, store, retrieve, organize, process)
what are some bedside tests to test cognitive-intellectual function?
test attention, orientation, memory, calculation, visuospatial ability, abstraction (similarities and differences) and insight
requires intact lower order systems (motor, sensory, vision, hearing, language)–> i.e regional cortical function
what is a primary cortex? give an example
first assessment of input
i.e primary vision cortex
what is a unimodal cortex? give an example
association areas, i.e visual association areas
what is a heteromodal cortex? give an example
receives input from other heteromodal cortices–> i.e entorhinal cortex (below hippocampus)
what does the orbitofrontal cortex do?
inhibits urges, delays gratification
what does the dorsolateral prefrontal cortex do?
practice alternatives before making a decision (executive function)
what does the ventromedial cortex do?
emotion experience and meaning of events
what does the anterior cingulate gyrus do?
attention focusing, tuning into one’s thoughts, apathy
what does CIF stand for?
cognitive-intellectual function
what does the MSSE test?
- orientation (recent memory)
- naming (memory and language)
- serial 7s/world backwards (attention and calculation)
- recall (memory)
- naming (memory and language)
- repetition (language)
- 3 step command (language, memory, sequencing)
- read (language)
- write (language)
- copy (2-D visuospatial)
what neuroanatomical structures are association with attention?
arousal starts in the RAF and thalamus –> goes to right heteromodal cortices (especially the prefrontal and posterior parietal cortices)
limbic system adds mood and motivation
**in impairment of attention, delirium represents global failure of CIF (attention, recent and remote memory, calculation and visuospatial)
what 4 bedside tests assess attention?
- digit span (repeat 7 numbers forward, 5 backwards)
- A test (raise hand every time you hear the letter A)
- serial 7s (not a good attention task as it involves calculation as well)
- world backwards (working memory)
what are 4 bedside tests for recent/episodic memory?
- 3 word test
- 3 shape test
these test attention, encoding and retrieval
if have 2/3, encoded but no retrieval (forgetful)
if 0/3 there is no encoding (amnesia)
what function is missing in amnesia?
encoding
what is remote/semantic memory?
recall of learned material
what neuroanatomical structures are involved in remote/semantic memory?
inferolateral cortex and pole of temporal lobes, LEFT (dominant?) side only
what bedside test assesses remote/semantic memory?
animal fluency test (less than 15 in 1 minute is impaired)
what is the clinical presentation of someone with a semantic memory problem?
i.e semantic amnesic syndrome
impaired remote memory, anomia, preserved recent memory, intact attention and intellect, impaired comprehension of common concepts
what is the anatomy of calculation?
DOMINANT parietal cortex –> heteromodal
what is the anatomy of visuospatial ability?
NON-dominant parietal cortex
what are the non-memory CIFs?
calculation and visuospatial
what is a mnemonic to remember TREATABLE causes of dementia?
DEMENTIA (these causes are treatable)
Drugs (too many, too few, wrong ones)
Emotional problems (depressions, psychosis)
Metabolic disturbances (hyponatremia, alkalosis etc)
Endocrine disturbances (hypo or hyperglycemia, hypo or hyperthyroid, hypercalcemia etc)
Nutritional problems (B12, folate)
Trauma (i.e subdural hematoma)//Tumor (including paraneoplastic syndromes)
Infections (neurosyphilis)
Anemia//Alcohol
what are the most common causes of dementia?
alzheimer’s disease –> gradual onset and progression, prominent amnesia
vascular dementia–> encompasses multi-infarct dementia, white matter disease, and (less commonly) single large CVAs–> often stepwise in progression and having focal neurological symptoms and signs
other than alzheimer’s and vascular dementia, what are 7 other neurodegenerative causes of dementia?
- dementia with lewy bodies (DLB)
- parkinson’s disease and parkinson’s plus syndromes
- frontotemporal dementia
- normal pressure hydrocephalus
- huntington’s disease
- HIV
- cruetzfeld-jacob disease (prion)
what is dementia with lewy bodies?
criteria include fluctuations in course, hallucinations, sensitivity to antipsychotics, prone to falls and extrapyramidal signs
how is parkinson’s disease/parkinson’s plus syndromes related to dementia?
a neurodegenerative cause of dementia
i.e progressive supranuclear palsy–> presence of extramyramidal symptoms and signs as well as cortical and subcortical features
what is frontotemporal dementia?
YOUNGER age of onset than alzheimer’s disease
prominent behavioral changes including social conduct dysregulation, disinhibitions and emotional blunting OR prominent language impairment (i.e progressive NON-fluent aphasia or semantic problems, with breakdown of words meaning and knowledge)
what are symptoms of normal pressure hydrocephalus?
ataxia, urinary incontinence
what % of dementias have a known genetic cause?
only a fraction
what is the abnormality (mutation) associated with most types of genetically related dementia?
missense mutations
what genes are involved in alzheimer’s disease?
APP
PS-1
PS-2
ApoE is a susceptibility gene only
what genes are involved in frontotemporal dementia?
MAPT
PRGN
what genes are involved in CADASIL (a type of vascular dementia)?
NOTCH 3
when are patients tested for genetically-related dementia?
there exists strict guidelines for predictive genetic testing of asymptomatic “at risk” individuals–> patients are typically not tested unless there is a strong genetic background
what are the patterns of inheritance associated with dementia?
include sporadic and autosomal dominant
what is the believed cause of alzheimer’s disease?
thought to be caused by pathology in proteins A-beta and tau
what is amyloid precursor protein (APP)? how is it processed by the body, and how does this relate to alzheimer’s?
belongs to a family of membrane inserted glycoproteins expressed by neurons and other cells
majority of APP is normally broken down by alpha and gamma secretase generating p3
minority of APP is processed y beta and gamma secretase generating A-beta, an amylogenic product
A-beta protein is amylogenic in vitro and is a major constituent of senile plaques and congophilic angiopathy–> it varies in amino acid length from 39-43 and is an abnormal/minor metabolite of APP
**amyloid/senile plaques are also present in normal aging (but more in alzheimer’s)
what is A-beta protein?
produced by conversion of APP by beta and gamma secretase
A-beta protein is amylogenic in vitro and is a major constituent of senile plaques and congophilic angiopathy–> it varies in amino acid length from 39-43 and is an abnormal/minor metabolite of APP
describe the pathophysiology of early-onset familial alzheimer’s
APP mutation near enzymatic cleavage site results in increased production of A-beta protein
mutations in PS-1 and PS-2 (components of gamma secretase) results in increased production of A-beta42
APP, PS-1 and PS-2 are therefore the causative genes of alzheimer’s disease
describe the pathophysiology of late onset familial alzheimer’s
carriers of E4 allele of ApoE gene are associated with higher risk of sporadic alzheimer’s
E4 protein isoform binds A-beta protein with high avidity, thereby increasing its amylogenic potential
E4 allele of ApoE is therefore the susceptibility gene of alzheimer’s
what is tau protein?
microtubule-associated protein
different neurons express different isoforms of tau
hyperphosphorylation of tau results in the formation of paired helical filaments (PHF) and straight filaments
PHFs are the major constituent of NEUROFIBRILLARY TANGLES, plaque associated neuritis and neuropil threads
how is inflammation related to alzheimer’s pathophysiology?
thought to play a key role in accelerating the progression of alzheimer’s by causing further neuronal damage as amyloid genesis occurs
however, there is no evidence that supports tx with anti-inflammatory drugs
what are the diagnostic criteria for dementia?
the presence of an acquired impairment in memory, associated with an impairment in one or more cognitive domains including:
- executive function (abstract thinking, reasoning, judgement)
- language (expressive or receptive)
- praxis (learned motor sequences)
- gnosis (ability to recognize objects, faces or other sensory information)
impairments in cognition must be severe enough to interfere with work, usual social activities or relationships with others
what is the diagnostic criteria for alzheimers?
- dementia established by means of clinical diagnosis and cognitive testing
- progressive worsening of memory and other cognitive functions
- no disturbance on consciousness
- absence of systemic disorders or other brain diseases that could account for the progressive cognitive decline
- supportive features include:
- altered behavioural patterns
- family history of similar disorders, particularly if have confirmed neuropathology - features that make a diagnosis of alzheimer’s uncertain or unlikely:
- sudden onset
- focal neurological findings, including hemiparesis, sensory loss, visual field deficits or incoordination
- early presence of a gait disorder ot seizure
what are important things to note on the history and physical exam in someone with suspected dementia/alzheimers?
inquire about onset, duration, and evolution
substance abuse
metabolis disorders
systemic illnesses
depression
stroke
family history
physical exam should be NORMAL in alzheimer’s disease
should expect focal neurological deficits for vascular dementia and parkinson’s symptoms with dementia with lewy bodies or parkinson’s dementia
list the psychometric/cognitive screening tests that can be useful in assessing/making the diagnosis of dementia
- MSSE
- MoCA
- clock drawing test
how is the MSSE scored?
out of 30
mild is 18-16
moderate is 10-18
severe is less than 10
widely used in research and clinical settings but lacks sensitivity to detect mild cognitive impairment levels
how is the MoCA scored? what is an advantage of the MoCA over the MSSE?
scored out of 30, cut off score is less than 26
more sensitive than the MSSE in detecting alzheimer’s and mild cognitive impairment
what is the clock drawing test?
score range is varied
test for dementia
widely used in research and clinic setting but lacks sensitivity to detect mild cognitive impairment levels
what is the primary role of lab tests and CT/MRIs in the assessment and diagnosis of dementia/alzheimers?
primary role is to rule out the rare presence of a treatable disorder presenting as memory loss such as renal failure, brain tumour, normal pressure hydrocephalus and subdural hemorrhage
what are the basic lab investigations for dementia?
CBC
TSH
serum calcium
electrolytes and fasting glucose
renal function
what are the selective lab tests for dementia?
B12
rapid plasma regain (RPR) for syphilis
HIV antibodies
what are you looking for on CT/MRI in the case of dementia/alzheimer’s?
CT/MRI imaging permits assessment of early atrophy in medial temporal lobe suggestive of alzheimer’s
also, imaging allows exclusion of neurosurgical lesions including tumours, subdural hematomas and hydrocephalus
**brain atrophy does NOT correlate well with clinical signs and symptoms of alzheimer’s disease