Differential Diagnosis of Dementia Flashcards
Give a clinical definition of dementia Discuss the most common forms of dementia and their typical features of presentation Describe the pathway from presentation to examination, investigation, and treatment Appreciate the broad spectrum of pathological disturbances that can result in a clinical syndrome of dementia
Define dementia
An insious onset of progressive mental decline that interferes with the activities of daily living. Consciousness is not impaired, but there are deficits in behaviour, attention, memory, language, and visuospatial function
Name four things which can confound a dementia diagnosis
Drugs, psychiatric disease, focal neurological syndromes, and acute confusional states
Describe the differences between normal cognitive decline with ageing and dementia
Normal ageing: Temporal orientation, immediate attention, vocabulary, visuospatial skills, judgement, and insight all preserved. Mild decrements develop in sustained attention, visual recall, naming, response speed, and flexibility
Define mild cognitive impairment
Greater impairment to cognitive function than expected with normal ageing, but insufficient to reach the criteria for dementia
What percentage of mild cognitive impairment patients convert to dementia annually?
10-15%
Describe the typical presentation of AD
Insidious amnesia and language impairment - anomia, paraphrasias, poor comprehension
Describe the typical presentation of FTD
Lack of hygiene, personality change, poor comportment and planning
Describe the typical presentation of Lewy body dementia
Agitation, hallucinations, visuospatial dysfunction, neuroleptic sensitivity, later parkinsonism
Describe the typical presentation of normal pressure hydrocephalus
Memory loss, ataxia, incontinence
Describe the typical presentation of Creutzfeldt-Jakob disease (CJD)
Subacute or rapid cognitive decline with motor signs
Name 3 neurological causes of visual hallucinations
Parkinson’s disease, dementia with Lewy bodies, epilepsy, migraine, hemispheric or brainstem lesions
Name 3 psychiatric causes of visual hallucinations
Psychosis (e.g. schizophrenia), delirium, mood disorders
Name 3 toxic or metabolic causes of visual hallucinations
Medication, alcohol, drugs of abuse, drug withdrawal, uraemia
Define Charles Bonnet syndrome
Development of complex visual hallucinations in individuals with acquired vision loss, with insight and without cognitive impairment
State 5 common characteristics of visual hallucinations in Charles Bonnet syndrome
Simple geometric shapes, faces and objects, tesselopsia (regular, overlapping patterns), prosometamorphopsia (facial distortion), dendropsia (branching forms), polyopia (multiple forms of one image)
Define paraphrenia
A late-onset psychotic and paranoid syndrome in patients with hearing and visual loss, which can also cause Charles Bonnet syndrome with additional auditory hallucinations
What percentage of patients referred to neurology with suspected dementia actually have depression?
8-15%
What percentage of dementia patients also have depression?
20-30%
State 5 clues that a patient has depression and not dementia
Prior or family history of depression, subacute onset, delusions, agitation or pacing, complaints of poor memory, poor effort, spared language, normal imaging
Define delirium
Impairment to the stream of thought and consciousness, accompanied by cognitive deficits such as impaired attention, thought intrusion, hallucinations, apathy, and agitation, with a fluctuating course
How can delirium and dementia be distinguished?
Dementia does not affect consciousness
Describe some symptoms of subcortical lesions
Apathy, mood changes, personality changes, motor signs, general slowing and inefficiency
Describe some symptoms of cortical lesions
Language deficits, visuospatial dysfunction, disinhibition
State the 4 aims of the history and examination
Establish the suspected syndrome (what), localisation (where), potential pathophysiology (how), and hence further investigations and treatment (what to do)
Name 2 neoplastic causes of a dementia-like presentation
A frontal mass and limbic encephalitis
Name an iatrogenic cause of a dementia-like presentation
Episodes of hypoglyaemia in a diabetic on insulin
Name a traumatic cause of a dementia-like presentation
Bilateral subdural haematomas
