Differential Diagnosis of Dementia

Question 1

Define dementia

Answer 1

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

Question 2

Name four things which can confound a dementia diagnosis

Answer 2

Drugs, psychiatric disease, focal neurological syndromes, and acute confusional states

Question 3

Describe the differences between normal cognitive decline with ageing and dementia

Answer 3

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

Question 4

Define mild cognitive impairment

Answer 4

Greater impairment to cognitive function than expected with normal ageing, but insufficient to reach the criteria for dementia

Question 5

What percentage of mild cognitive impairment patients convert to dementia annually?

Answer 5

10-15%

Question 6

Describe the typical presentation of AD

Answer 6

Insidious amnesia and language impairment - anomia, paraphrasias, poor comprehension

Question 7

Describe the typical presentation of FTD

Answer 7

Lack of hygiene, personality change, poor comportment and planning

Question 8

Describe the typical presentation of Lewy body dementia

Answer 8

Agitation, hallucinations, visuospatial dysfunction, neuroleptic sensitivity, later parkinsonism

Question 9

Describe the typical presentation of normal pressure hydrocephalus

Answer 9

Memory loss, ataxia, incontinence

Question 10

Describe the typical presentation of Creutzfeldt-Jakob disease (CJD)

Answer 10

Subacute or rapid cognitive decline with motor signs

Question 11

Name 3 neurological causes of visual hallucinations

Answer 11

Parkinson’s disease, dementia with Lewy bodies, epilepsy, migraine, hemispheric or brainstem lesions

Question 12

Name 3 psychiatric causes of visual hallucinations

Answer 12

Psychosis (e.g. schizophrenia), delirium, mood disorders

Question 13

Name 3 toxic or metabolic causes of visual hallucinations

Answer 13

Medication, alcohol, drugs of abuse, drug withdrawal, uraemia

Question 14

Define Charles Bonnet syndrome

Answer 14

Development of complex visual hallucinations in individuals with acquired vision loss, with insight and without cognitive impairment

Question 15

State 5 common characteristics of visual hallucinations in Charles Bonnet syndrome

Answer 15

Simple geometric shapes, faces and objects, tesselopsia (regular, overlapping patterns), prosometamorphopsia (facial distortion), dendropsia (branching forms), polyopia (multiple forms of one image)

Question 16

Define paraphrenia

Answer 16

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

Question 17

What percentage of patients referred to neurology with suspected dementia actually have depression?

Answer 17

8-15%

Question 18

What percentage of dementia patients also have depression?

Answer 18

20-30%

Question 19

State 5 clues that a patient has depression and not dementia

Answer 19

Prior or family history of depression, subacute onset, delusions, agitation or pacing, complaints of poor memory, poor effort, spared language, normal imaging

Question 20

Define delirium

Answer 20

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

Question 21

How can delirium and dementia be distinguished?

Answer 21

Dementia does not affect consciousness

Question 22

Describe some symptoms of subcortical lesions

Answer 22

Apathy, mood changes, personality changes, motor signs, general slowing and inefficiency

Question 23

Describe some symptoms of cortical lesions

Answer 23

Language deficits, visuospatial dysfunction, disinhibition

Question 24

State the 4 aims of the history and examination

Answer 24

Establish the suspected syndrome (what), localisation (where), potential pathophysiology (how), and hence further investigations and treatment (what to do)

Question 25

Name 2 neoplastic causes of a dementia-like presentation

Answer 25

A frontal mass and limbic encephalitis

Question 26

Name an iatrogenic cause of a dementia-like presentation

Answer 26

Episodes of hypoglyaemia in a diabetic on insulin

Question 27

Name a traumatic cause of a dementia-like presentation

Answer 27

Bilateral subdural haematomas