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Common types of dementia




Table 10.1 Characteristic features of common types of dementia



alzheimer's dementia

lewy body dementia (lbd)

vascular dementia

fronto- temporal dementia

Age at onset


70 – 80

70 – 80

60 – 70

50 – 60

Percentage of dementia

50 – 60%

10 – 20%

10 – 20%

10% (higher proportion in ages < 60)

First symptoms

Short-term memory loss

Slowness, problems with visuospatial tasks

General slowing of cognition, may have depression at onset

Behavioural changes, language changes, apathy

Associated symptoms      

Lack of insight into memory difficulties may be present



History of

mild cognitive impairment in some individu- als


Co-occurring cerebrovas- cular disease common

Parkinsonian symptoms (rigidity, slow- ness, may not have tremor)



(often vi-

sual and non- frightening)


Early falls


Marked fluctuations in consciousness (can appear drowsy or delirious)


Sleep distur- bance (REM sleep disor- der – "act out" dreams)

Registration of events better than recall (more likely to recall when given cues)


"Patchy deficits": may have marked deficits in language

with relative preservation in language


Pure vascular dementia

less common than mixed vascular and AD

Eating disturbances, (overeating, carbohydrate craving)




Loss of insight



in social skills


May be as- sociated with movement disorders or motor neuron disease


Family history

Increased risk of AD

Often no fam- ily history

Cardiovas- cular, cere- brovascular disease

Strong fam- ily history in many cases (20 – 40%)

Neurological signs

Absent early on

Parkinsonian symptoms

Many have focal weak- ness, reflex changes

Frontal release signs (grasp, glabel- lar tap, snout reflexes)


5 – 15 year course Slowly pro- gressive

2 – 3 point decline yearly on MMSE

Rapid progres- sion from on- set to severe symptoms

over few years

Variable "step-wise decline"

Rapidly pro- gressive over few years