Disorders Of Cognition

Question 1

Subtypes for Acute cognition disorders

Answer 1

Brain insults
Global Transient Amnesia
Transient Epileptic Amnesia

Question 2

What is Transient Global Amnesia?

Answer 2

Abrupt onset antegrade amnesia with preserved knowledge of self
4-6hrs
Triggers by emotions/ temperature

Question 3

Transient Epileptic Amnesia

Answer 3

Forgetful/ repetitive questioning
20-30 mins
Can carry out complex tasks with no recollection
Associated with temporal lobe seizure
+ response to AED

Question 4

Name two subacute cognitive disorders

Answer 4

Functional/ subjective cognitive impairment
Creutzfelt-Jakob disease

Question 5

What is Creutzfelt-Jakob disease?

Answer 5

A prion disease

Question 6

What is a prion disease?

Answer 6

Transmissible neurodegenerative disease caused by prion proteins. These proteins induce the formation of amyloid folds resulting in tightly packed beta-pleated sheets resistant to proteases.

Question 7

Clinical features of CJD

Answer 7

Rapid onset dementia
Myoclonus

Question 8

Investigation findings for CJD

Answer 8

CSF is usually normal
EEG: biphasic, high amplitude sharp waves (only in sporadic CJD)
MRI: hyperintense signals in the basal ganglia and thalamus

Question 9

How is Dementia defined?

Answer 9

Loss of cognitive function in 2 or more domains:
Episodic memory
Language functioning
Frontal executive functioning
Visuospatial functioning
Apraxia
Causing loss of function in some way

Question 10

Aetiology of dementia

Answer 10

V: vascular, vitamin deficiency: B1, B6, B12, folate
A: Alzheimer disease, autoimmune: cerebral vasculitis, systemic lupus erythematosus
N: normal pressure hydrocephalus, neoplasia
I: infection, e.g. Creutzfeldt-Jakob disease, herpes simplex encephalitis, prion diseases, tertiary syphilis, HIV/AIDS, PML
S: substance abuse, serum abnormalities e.g. hyperammonaemia, uraemia, Wilson disease
H: hormones: hypothyroidism, hyperparathyroidism
E: electrolyte disturbances: e.g. hyponatraemia, hypokalaemia, hypocalcaemia, hypercalcaemia etc.
D: depression (pseudodementia)

Question 11

Clinical features of Alzheimer’s disease

Answer 11

Memory impairment
Language (difficulty with word finding)
Apraxia (decreased ability to carry out complex motor skills)
Agnosia (inability to name objects)
Anosognosia (lack of insight into their difficulties)
Executive dysfunction (organising sequencing impaired)
Visuospatial impairment (difficulty with orientation in space and navigation)
PERSONALITY AND SOCIAL BEHAVIOUR REMAIN INTACT UNTL LATE STAGE AD

Question 12

Histopathological changes in AD

Answer 12

microscopic: cortical plaques due to deposition of type A-Beta-amyloid protein and intraneuronal neurofibrillary tangles caused by abnormal aggregation of the tau protein and hyperphosphorylation of the tau protein has been linked to AD

biochemical : there is a deficit of acetylcholine from damage to an ascending forebrain projection

Question 13

How is vascular dementia differentiated from AD?

Answer 13

Progresses in a stepwise fashion often showing periods of stability at one level of functioning then acute decline followed by stability
Apraxic gait disorder, incontinence and pyramidal signs

Focal neurological abnormalities e.g. visual disturbance, sensory or motor symptoms
The difficulty with attention and concentration
Seizures
Memory disturbance
Gait disturbance
Speech disturbance
Emotional disturbance

Question 14

MRI changes in AD

Answer 14

widespread cerebral atrophy, particularly involving the cortex and hippocampus

Question 15

MRI changes in vascular dementia

Answer 15

Affects white matter of both cerebral hemispheres, grey nuclei and thalamus

Question 16

Features of Lewy Body Dementia

Answer 16

progressive cognitive impairment
typically occurs before parkinsonism, but usually both features occur within a year of each other. This is in contrast to Parkinson’s disease, where the motor symptoms typically present at least one year before cognitive symptoms
cognition may be fluctuating, in contrast to other forms of dementia

in contrast to Alzheimer’s, early impairments in attention and executive function rather than just memory loss
parkinsonism

visual hallucinations (other features such as delusions and non-visual hallucinations may also be seen)

Question 17

Characteristic pathological feature of Lewy Body dementia

Answer 17

alpha-synuclein cytoplasmic inclusions (Lewy bodies) in the substantia nigra, paralimbic and neocortical areas