Cognitive impairment Flashcards
Explicit memory
Declarative memory - all stored material of which the individual is consciously aware
Implicit memory
Procedural memory - all material that is stored without the individual’s conscious awareness e.g. the ability to speak a language or ride a bike
Semantic memory
Knowledge of facts e.g. world capitals
Episodic memory
Knowledge of autobiographical events
Dysphasia/aphasia
Loss of language abilities despite intact sensory and motor function
Receptive dysphasia
Difficulty in understanding commands or other words
Expressive dysphasia
Difficulty using words with the correct meaning
Nominal dysphasia
Not being able to name items despite knowing what they are - subtype of expressive dysphasia
Dyspraxia/apraxia
Loss of ability to carry out skilled motor movements despite intact motor function
Dysgnosia/agnosia
Loss of ability to interpret sensory information despite intact sensory organ function e.g. not able to recognise faces as familiar
Amnesia
Loss of ability to learn or recall new information, or to retrieve memories that have previously been stored
Executive function
Ability to plan and sequence complex activities or to manipulate abstract information (e.g. to plan the preparation of a meal)
Anterograde amnesia
Occurs after an amnesia-causing event; the patient is unable to store new memories from the event onwards, but ability to retrieve memories from before is unimpaired
What part of the brain is usually damaged, resulting in anterograde amnesia?
Medial temporal lobes, especially the hippocampal formation
Retrograde amnesia
Being unable to retrieve memories stored before an amnesia-causing event, although able to store new memories from the event onwards
What part of the brain is usually damaged, resulting in retrograde amnesia?
Frontal or temporal cortex
Risk factors for delirium (4)
- An abnormal brain (e.g. dementia or previous serious head injury)
- Age
- Polypharmacy
- Sensory impairment
Delirium
Acute and fluctuating cognitive impairment +/- psychotic features
High mortality - 1/3rd due during the presentation
Causes of delirium (systemic illnesses)
Infections and sepsis
Anoxia:
- Respiratory failure
- Heart failure
- MI
Metabolic and endocrine: -Electrolyte disturbances -Uraemia -Hepatic encephalopathy -Porphyria -Hypoglycaemia -Hyper/hypothyroidism -Hyper/hypoparathyroidism -Cushings/Addisons Hypopituitarism
Nutritional:
- Thiamine deficiency (Wernicke’s encephalopathy)
- Vitamin B12 deficiency
- Folic acid deficiency
- Niacin deficiency (pellagra)
Causes of delirium (drugs or their discontinuation)
Prescribed:
- Anticholinergics
- Benzodiazepines
- Opiates
- Antiparkinsonian drugs
- Steroids
Recreational:
- Alcohol withdrawal
- Opiates
- Cannabis
- Amphetamines
Poisons:
- Heavy metals (lead, mercury, manganese)
- Carbon monoxide
Causes of delirium (intracranial)
Space-occupying lesions:
-Tumours, cysts, abscesses, haematomas
Head injury (especially concussion)
Infection:
- Meningitis
- Encephalitis
Epilepsy
Cerebrovascular disorders:
- TIA
- Cerebral thrombosis or embolism
- Intracerebral or subarachnoid haemorrhage
- Hypertensive encephalopathy
- Vasculitis
Impaired cognitive function in delirium
- Short-term and recent memory impairment with relative preservation of remote memory.
- Almost always disorientated to time, often to place, rarely to person
- Language abnormalities: rambling, incoherent speech and receptive dysphasia
Perceptual and thought disturbance in delirium
- Misinterpretations, illusions and hallucinations (especially visual)
- Transient persecutory delusions and delusions of misidentification
Sleep-wake cycle disturbance in delirium
Range from daytime drowsiness and night-time hyperactivity, to a complete reversal of the normal cycle
Nightmares may continue as hallucinations after awakening
Mood disturbance in delirium
Depression, euphoria, anxiety, anger, fear and apathy are all common
Dementia
A syndrome of acquired progressive generalised cognitive impairment associated with functional decline (difficulties with ADL). Consciousness level is normal
How long do symptoms need to be present before a diagnosis of dementia can be made?
6 months
Basic ADLs
Self-care tasks such as eating, dressing, washing, toileting, continence and mobility
Instrumental ADLS
Tasks which are not crucial to life but allow someone to live independently e.g. cooking, shopping and housework
BPSD
Behavioural and psychological symptoms of dementia - non-cognitive symptoms associated with dementia
- Behavioural symptoms are common: pacing, shouting, sexual disinhibition, aggression and apathy
- Depression and anxiety in up to 50%
- Delusions (especially persecutory) in up to 40%
- Hallucinations in 30% (visual most common)
What percentage of patients with dementia will experience seizures?
Between 10-20% Primitive reflexes (e.g. grasp, snout, suck), as well as myoclonic jerks
Early onset dementia
Beginning before 65yrs old
Causes of dementia other than neurodegenerative or cerebrovascular disease
Space-occupying lesions
• Tumours, cysts, abscesses, haematomas
Trauma
• Head injury
• Punch-drunk syndrome (dementia pugilistica)
Infection
• Creutzfeldt–Jakob disease (including ‘new variant CJD’)
• HIV-related dementia
• Neurosyphilis
• Viral encephalitis
• Chronic bacterial and fungal meningitides
Metabolic and endocrine
• Chronic uraemia (also dialysis dementia)
• Liver failure
• Wilson’s disease
• Hyper- and hypothyroidism
• Hyper- and hypoparathyroidism
• Cushing’s syndrome and Addison’s disease
Nutritional
• Thiamine, vitamin B12, folic acid or niacin deficiency (pellagra)
Drugs and toxins
• Alcohol, benzodiazepines, barbiturates, solvents
Chronic hypoxia
Inflammatory disorders
• Multiple sclerosis
• Systemic lupus erythematosus and other collagen
vascular diseases
Normal pressure hydrocephalus
Alzheimer’s disease
62%
Gradual onset with progressive cognitive decline
Early memory loss
Vascular dementia
17%
Focal neurological signs and symptoms
Evidence of cerebrovascular disease or stroke
May be uneven or stepwise deterioration in cognitive function
Mixed dementia
10%
Features of both Alzheimer’s disease and vascular dementia
Lewy body dementia
4%
Day-to-day (or shorter) fluctuations in cognitive performance
Recurrent visual hallucinations
Motor signs of parkinsonism (rigidity, bradykinesia, tremor) (not drug-induced)
Recurrent falls and syncope
Transient disturbances of consciousness
Extreme sensitivity to antipsychotics (induces parkinsonism)
Frontotemporal dementia
2% (includes Pick’s disease)
Early decline in social and personal conduct (disinhibition, tactlessness)
Early emotional blunting
Attenuated speech output, echolalia, perseveration, mutism
Early loss of insight
Relative sparing of other cognitive functions
Parkinson’s disease with dementia
2%
Diagnosis of Parkinson’s disease (motor symptoms prior to cognitive symptoms)
Dementia features very similar to those of Lewy body dementia
Ddx for cognitive impairment
Delirium Dementia Mild cognitive impairment Subjective cognitive impairment Stable cognitive impairment post insult, e.g. stroke, hypoxic brain injury, traumatic brain injury Depression (‘pseudodementia’) Psychotic disorders Mood disorders Intellectual disability Dissociative disorders Factitious disorder and malingering Amnesic syndrome
Mild cognitive impairment
Objective cognitive impairment (confirmed with a standardised test)
Around 10-15% of patient convert to dementia each year, but in some cases impairment remains stable, or even improves
Subjective cognitive impairment
When a patient complains of cognitive problems but scores normally on standardised tests.
Can reflect anxiety or depression, or represent early deterioration in a highly educated individual
Stable cognitive impairment
Impairment of one or more aspects of cognition caused by a ‘one-off’ insult, without progressive deterioration (e.g. CVA, hypoxic brain injury, viral encephalitis, traumatic brain injury)
Amnesic syndrome
Severe disruption of memory (anterograde and retrograde, with recent memories most affected), with minimal or no deterioration in the other cognitive functions. Also confabulation, lack of insight and apathy
Usually results from damage to the hypothalamic-diencephalic system or hippocampal region - commonest cause is Wernicke’s encephalopathy
Confabulation
Filling of gaps in memory with details which are fictitious, but often plausible
Causes of amnesic syndrome (Diencephalic damage)
Vitamin B1 (thiamine) deficiency, i.e. Korsakoff’s syndrome: - Chronic alcohol abuse - Gastric carcinoma - Severe malnutrition - Hyperemesis gravidarum Bilateral thalamic infarction Multiple sclerosis Post subarachnoid haemorrhage Third ventricle tumours/ cysts
Causes of amnesic syndrome (hippocampal damage)
Bilateral posterior cerebral artery occlusion Carbon monoxide poisoning
Closed head injury
Herpes simplex virus encephalitis
Transient global amnesia
What are you looking for in a physical examination when you suspect dementia?
- Reversible causes of impairment (hypothyroidism, space occupying lesion)
- Risk factors for dementia (hypertension, AF)
- Evidence of past CVA
- Complications of impairment (self-neglect, injuries from a fall)
AMT (Advantages and disadvantages)
Abbreviated Mental Test
A: Fast
D: Not sensitive to mild-moderate impairment
MMSE (Advantages and disadvantages)
Mini Mental State Exam
A: Covers most cognitive domains
D: Not sensitive to mild impairment, does not test executive function, influenced by premorbid IQ, language and culture
Clock Drawing Test (Advantages and disadvantages)
A: Tests praxis and executive function, resistant to influence from premorbid IQ, culture and language
D: Not sensitive to mild impairment, very influenced by poor motor control or visual impairment
ACE-R (Advantages and disadvantages)
Addenbrooke’s Cognitive Examination-Revised
A: Tests all cognitive domains, sensitive to mild impairment
D: Lengthy, influenced by premorbid IQ, language and culture
What investigations should you perform (according to NICE) to exclude reversible causes of dementia?
Vitamin B12/folate level
TFTs, calcium, glucose, U&Es
CT/MRI head scan
CT appearance of normal ageing
Progressive cortical atrophy and increasing ventricular size
CT appearance of Alzheimer’s disease
Generalized cerebral atrophy
Widened sulci
Dilated ventricles
Thinning of the width of the medial temporal lobe (in temporal lobe-oriented CT scans)
CT appearance of vascular dementia
Single/multiple areas of infarction
Cerebral atrophy
Dilated ventricles
CT appearance of frontotemporal dementia
Greater relative atrophy of frontal and temporal lobes Knife-blade atrophy (appearance of atrophied gyri)
CT appearance of Huntington’s disease
Dilated ventricles
Atrophy of caudate nuclei (loss of shouldering)
CT appearance of Creutzfeldt-Jakob disease
Usually appears normal
CT appearance of nvCJD
Bilaterally evident high signal in the pulvinar (post-thalamic) region
