Sep 28, 2017

7 Most Common Forms of Dementia

This is Part 2 of Leah Bisiani’s Understanding Dementia series – Read Part 1 here


The most common forms of dementia are:

Alzheimer’s disease (AD) is the most common form of dementia. Alzheimer’s causes difficulties with memory, thinking and behaviour. The rate at which Alzheimer’s progresses differs for everyone, however it is progressive.

Vascular dementia is the comprehensive term for dementia related to complications regarding circulation of blood to the CVA.

Lewy Body disease is caused by the degeneration and death of nerve cells in the brain, due to the existence of abnormal spherical structures, called Lewy bodies, which develop inside nerve cells.

Frontotemporal dementia (FTD) is due to progressive damage to the frontal and/or temporal lobes of the brain. The right and left frontal lobes are involved in mood, social behavior, attention, judgement, planning and self-control. Damage can cause reduced intellectual capabilities and changes in personality, emotion and behavior.

Alcohol related dementia is a form of dementia related to the excessive consumption of alcohol. This affects memory, learning and other mental functions. Korsakoff’s syndrome and Wernicke/Korsakoff syndrome are particular forms of alcohol related dementia.

Down syndrome and Alzheimer’s disease Down syndrome is a genetic disorder caused when there is 3 reproductions of chromosome 21 in every cell body instead of the usual pair, upsetting the gene balance. This extra gene makeup causes an assemblage of characteristics which can result in differing grades of developmental delay and some common physical traits.

HIV associated dementia. If a person has human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) they may develop a complication which is known as HIV associated dementia, or as AIDS Dementia Complex (ADC).

Alzheimer’s disease was first described in 1906 by Dr. Alois Alzheimer.

Alzheimer’s dementia is the most common form of dementia, accounting for 50-70% of all dementia

  •  A.D affects 7-10% 65+
  •  A.D affects 12-20% 85+.

There are two types of Alzheimer’s disease

  1. Sporadic Alzheimer’s Disease which can affect adults at any age, but usually occurs at 65+. This is the most common form, and affects those who may or may not have a family history of the disease.
  2. Familial Alzheimer’s Disease is hereditary and is quite rare. However having the gene means a 50% chance of developing Alzheimer’s Disease.

Both types of Alzheimer’s Disease include progressive atrophy of the brain, and scarring of brain tissue.

Because of the destruction of brain cells, and consequent cognitive decline, the person living with dementia gradually loses skills and abilities, with major changes in memory and behaviour.

Specialised care, including care specifically orientated to the individual, enables a person living with dementia to lead a more uplifting and empowering life for much longer.

The course of Alzheimer’s Disease is approximately 7 – 12 years, however, there is no typical presentation.


  • Protruding from the centre of neurons are many fine root hairs, called dendrites. Dendrites enable the brain to send messages from one part of the brain to another, and the body.
  • The ends of dendrites in our brain communicate with each other due to chemical changes within the tiny spaces, (synapses), between each cell.
  • Signals are carried through the gaps because of chemical changes, called neurotransmitters.

There are 3 major changes that are caused by Alzheimer’s Disease:

  •   Plaques – deposits of discarded protein fragment cell material, (beta—amyloid), on the outside of the neurons
  •   Neurofibrillary tangles – tangled growths, (tau) within the neurons, which are much thicker and coarser than normal hence normal function is destroyed
  •   Atrophy of the brain – as neurons die and dendrites are lost, shrinkage of the brain occurs

Although great advances have been made in understanding the brain pathology of A.D., the cause remains unknown.

There are thoughts and research in various fields that may lead to breakthroughs in the future.

It is important to appreciate that these suggested factors do not necessarily establish cause but may only represent links with the disease.

The single greatest risk factor for A.D. is age

A.D may be a disease of the brain, but most of the symptoms are changes in behaviour.

It is important to remember that these changes in behaviour are part of the disease and NOT a deliberate attempt on the persons part to be difficult.

Family and friends may notice the symptoms of Alzheimer’s and other progressive dementias before the person experiencing these changes.

If you or someone you know is experiencing possible symptoms of dementia, it is important to seek a medical evaluation to find the cause.

Subtle changes:

  • Lapses in memory/poor STM
  • Vagueness in everyday conversation
  • Loss of enthusiasm for previously enjoyed activity
  • Taking longer to complete routine tasks
  • Forgetting well known places
  • Inability to process instructions/questions
  • Deterioration of social skills
  • Emotional unpredictability

Warning signs:

  • Memory loss affecting day to day function
  • Difficulty performing familiar tasks
  • Problems with language
  • Disorientation to time and place
  • Poor or decreased judgement
  • Problems with abstract thinking
  • Misplacing things
  • Changes in mood or behaviour
  • Changes in personality
  • Loss of initiative

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