Types of Dementia

Disease
Dementia of Alzheimer Type (DAT)

Onset
Insidious (1-2 years before diagnosis and treatment sought)

Progression
Gradual and continuous over years

Course
Usually 8-10 years but variable (3-20 years)

Characteristics

Short term memory affected first, loss of executive functions (IADL first)
Orientation to time lost second
Orientation to place lost third
In later stages, loss of motor and sensory functions (hallucinations, delusions, apraxias, falls)

Disease
Vascular Dementia (VD)

Onset
Sudden

Progression
Step-like

Course
Variable

Characteristics

Presence of vascular risk factors (hypertension, hypercholesterolemia, diabetes, smoking, TIAs, atrial fibrillation or evidence of previous stroke)
Presentation varies according to area(s) of brain affected. May get focal deficits, gait problems, early incontinence, physical deficits
More likely to display agitation
Delusions & hallucinations less common

Disease
Frontotemporal Dementia (FTD)

Onset
Slow

Progression
More rapid than DAT

Course
2-7 years

Characteristics

Bizzare behaviours, incongruous with previous personality
More common in males
Age of onset earlier, before cognitive decline evident
Subsets with aphasia, apraxia & agnosia have frontal Pick's Bodies
Apathy
Behaviours usually socially inappropriate (explosive anger/agitation with loss of self awareness & growing disinhibition, grooming & hygiene problems)

Disease
Dementia of Lewy Body Type (LBD)

Onset
Slow

Progression
Rapid, fluctuating but progressive

Course
+/- 5 years

Characteristics

First fluctuating confusion Onset of hallucinations but cognition intact (except for SMMSE diagram or Clock)
Parkinsonism leading to increasing falls, gait disorder
Increased rigidity, decreased mobility Hypersensitive to neuroleptics (Hallucinations rarely eliminated while rigidity and tardive dyskinesia occurs)