There are several disorders that can lead to dementia. DAT is the most common and accounts for approximately 70% of all people diagnosed with dementia. Here is a general description of the most common types of dementia.
Dementia-Alzheimer’s Type (DAT). The human brain has tens of billions of neurons each of which is connected to thousands of other neurons. Unlike muscle, bone or skin cells, neurons are not ever replaced so throughout our lives we have fewer and fewer neurons as neurons die and are not replaced. Because we have so many neurons these losses only start to become noticeable as we move into old age. In DAT, this gradual loss of these neurons and their connections accelerates. In recent years it has been discovered that there is also a progressive accumulation of different types of proteins (amyloid and tau) in the brain which may account for the accelerated cell death. In the early stage of the disease, these changes generally affect parts of the brain that are associated with our ability to learn and retain new information. Therefore, the first symptoms generally consist of memory problems or rapid forgetfulness. As the disease progress, the pathology in the brain spread to other regions, which leads to other changes in thinking skills, behaviour, and in personality. These may include increased apathy and/or irritability, word finding difficulties, social withdrawal, socially inappropriate behaviour, and increased difficulty managing finances.
Vascular Dementia. Vascular dementia consists of cognitive decline that occurs because of problems with our vascular or circulatory system in the brain. This may result from a single event, such as a major stroke or the gradual accumulative effects of dozens or even hundreds of very mild strokes. A person with vascular dementia tends to show a more rapid onset of symptoms compared to what is seen in DAT. How quickly it progresses depends in part on when it is identified and whether contributing factors to the strokes, such as high blood pressure, can be controlled. The cognitive deficits associated with vascular dementia largely depend on which area of the brain was affected by the disease or the event, and hence are more variable in nature than those seen in DAT.
Frontotemporal Dementia or Frontal-Temporal Lobar Degeneration (FTLD). The term FTLD refers to the regions of the brain that are mostly affected by the disease (the frontal and temporal lobes of the brain). It is estimated that Frontotemporal dementia-spectrum disorders account for up to 20% of all pts with degenerative dementias. The condition typically presents between the age of 45 and 65 years old. Genetics factors remain at this time the only known cause for FTLD. We also know that there is a certain amount of overlap between patients with FTLD and patients with motor disorders, such as motor neuron disease (MND) or Amyotrophic Lateral Sclerosis (ALS). It can be difficult to distinguish between DAT and FTLD as both diseases share a number of similarities, such as insidious onset and progressive difficulties with memory and language. Personality changes, such as appearing more indifferent or depressed or being more socially inappropriate or careless can also occur in both DAT and FTLD, but in DAT these changes usually occur at a later stage in the disease compared to FTLD. There are several types of FTLD, which essentially depend on the regions in the brain that are predominantly affected. The most common type of FTLD is called the Behavioral variant of FTLD and involves primarily personality and behavioural changes. It accounts for approximately 56% of all FTLD and progresses relatively rapidly (an estimated time of 3.4 years from diagnosis to death). Other variants of FTLD start with a decline in a person’s language skills or a person’s ability to express himself/herself and/or to understand what other people are saying.