This section of the website includes some more in depth facts about dementia including:
- What is young on-set dementia?
- Is dementia hereditary?
- What is mild cognitive impairment?
- What is meant by time-shift and how can reminiscence therapy help?
- A more detailed look at how Alzheimer’s disease progresses.
- What drugs are available to treat dementia?
- The stigma of dementia.
Below is a summary of how dementia is categorised (cortical or sub-cortical), classified (primary or secondary) and the difference between reversible and irreversible dementia.
Dementia may be categorised as follows:
Cortical or subcortical dementia
The type of dementia may be classified as either cortical or subcortical depending on which part of the brain is the primary location of dementia.
Overview of the cerebrum
The cerebrum, is the largest and most highly developed part of the human brain, it accounts for about two-thirds of the brain mass and lies over and around most of the structures of the brain.
A deep groove that runs from front to back divides into the left and right halves known as the two cerebral hemispheres. Each hemisphere is in turn divided into four lobes.
The surface of the cerebral hemispheres is covered by a thin layer known as the cerebral cortex or simply the cortex. It contains billions of brain cells called grey matter.
Underneath the cortex are bundles of nerve fibres known as white matter, which transport nerve signals between parts of the cortex and from the cortex to other parts of the brain.
Cortical dementia is typically associated with the brains grey matter.
Types of cortical dementia
- Language – inability to find the right words.
- Processing information – Understanding what others are saying.
Subcortical dementia are believed to initially effect the structures below the cortex and are more associated with the brain’s white matter.
Types of subcortical dementia
- Personality changes.
- Slow thought processes.
Some types of dementia appear to affect both the cortical and subcortical areas of the brain such as Lewy body dementia and vascular dementia.
Primary or secondary dementia
The type of dementia can also be classified as primary or secondary dementia depending on whether the dementia relates to any other disease.
Primary dementia is where the dementia itself is the major sign of brain disease not directly related to any other illness and include:
Secondary dementias are those caused by or closely related to some other recognisable disease such as aids or a stroke.
Irreversible or reversible dementia
The majority of dementias are progressive i.e. will get worse over time, are irreversible and will result in death.
Irreversible dementias include:
However, there are some that are reversible i.e. it doesn’t inevitably get worse over time and recovery is possible.
Reversible dementias include:
- B12 deficiency.
- Thyroid deficiency.
- Brain tumors.
- Normal pressure hydrocephalus.