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 (average) | 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 early
History of mild cognitive impairment in some individu- als
Co-occurring cerebrovas- cular disease common | Parkinsonian symptoms (rigidity, slow- ness, may not have tremor)
Hallucinations (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)
Disinhibition
Loss of insight
Impairment 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) |
Progression | 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 |
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