Dementia refers to a neurodegenerative process whereby a person experiences cognitive and functional decline. Such decline is over and above the gradual decline experienced in normal ageing. As such, it can be difficult to determine when a person is in the early stages of dementia. There are many different forms of dementia, including:
- Alzheimer's Dementia: This represents the manifestation of Alzheimer's Disease, a pathological brain process. Alzheimer's Disease can only be diagnosed on autopsy but Alzheimer's Dementia can be diagnosed while a person is living. This form of dementia is associated with memory encoding deficits (difficulty forming new memories) and problems with object naming and carrying out routine practical tasks (dyspraxia).
- Vascular Dementia: Although it is highly associated with stroke, it may occur in someone who has not experienced an obvious stroke, and not all people who sustain strokes will develop Vascular Dementia. The memory difficulties in Vascular Dementia relate more to the organisation and retrieval of information from mind and tend to be variable.
- Dementia with Lewy Bodies: This is a form of dementia associated with a high number of particular proteins (called Lewy Bodies) within brain cells. Dementia with Lewy Bodies tends to present with Parkinsonian features, visual hallucinations, variable cognition and early difficulties with attention, processing speed, visuo-spatial functioning and executive skills.
- Fronto-Temporal Dementia: This refers to a range of dementias associated with degeneration of the frontal and temporal lobes.
Dementia of the Frontal Lobe Type is associated with significant changes in behaviour, personality and mood. A person with this condition may become socially disinhibited, impulsive, disorganized and irritable. Conversely, they may become apathetic, disengaged and blunted in their emotions.
Semantic Dementia is associated with a loss of knowledge about objects and concepts, however, day to day memory is usually relatively well preserved.
Primary Progressive Aphasia is associated with word-finding difficulties, grammatical errors and articulation errors. Memory and other cognitive skills are usually well preserved, even though a person with this condition may progress to mutism.