Types of Dementia

Common types of dementia are Alzheimer disease (40-60%), vascular dementia (10-20%), and Lewy Body dementia (15-20%). Other causes are frontal lobe dementia, Parkinson disease with dementia, normal pressure hydrocephalus, post-traumatic, medications, alcohol, anoxic encephalopathy, prion diseases (eg. Cretzfeldt-Jacob disease), Huntington disease, Down syndrome and AIDS. Dementia may be due to a combination of causes.

Alzheimer's disease is characterised by an insidious onset of symptoms, with initial forgetfulness progressing over time to profound memory impairment with accompanying dysphasia, dyspraxia and personality change. Noncognitive symptoms may include decreased emotional expression and initiative, increased stubbornness and suspiciousness, and delusions.

Vascular dementia usually starts suddenly, with focal neurological signs and imaging evidence of cerebrovascular disease. There may be emotional lability, impaired judgment, gait disorders, with relative preservation of personality and verbal memory. It often occurs in combination with Alzheimer disease.

Lewy Body dementia is characterised by cognitive impairment that affects memory and the ability to carry out complex tasks, and fluctuates within 1 day. It is associated with at least one of the following: visual or auditory hallucinations, spontaneous motor parkinsonism, transient clouding or loss of consciousness, and repeated unexplained falls.

Frontal lobe dementia features include impaired initiation and planning, with disinhibited behaviour and mild abnormalities on cognitive testing. Apathy and memory deficit may appear later.

RACGP Medical care of older persons in residential aged care facilities 4th edition. [g.26]