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Q) I have been told that my dad is suffering from dementia. I understand that Alzheimerís is not the only type. What are they and do we treat them differently?
A) Dementia is a general term for a number of disorders that differ in how they arise but share many similarities in how they present themselves.
It is estimated that about 564,000 Canadians currently have one of these diseases and with the greying of the population that number is expected to shoot up to 937,000 by 2031. Obviously, dementia is a problem right now and one that is only going to grow in magnitude in the coming years.
Symptoms of dementia are gradual, persistent and increase over time. While the symptoms vary greatly between individuals, they frequently involve some degree of memory loss, an inability to recognize known objects (agnosia), an inability to perform learned tasks (apraxia), communication and language impairments, poor visuospatial functioning and faulty reasoning, judgement or planning skills. Distinguishing between them is a very tricky bit of business given the commonality of symptoms so it involves a multi-pronged approach utilizing a detailed patient history, physical examination, cognitive assessment and laboratory testing.
Neuroimaging tools such as MRIís and CT scans can further establish the diagnosis.
Of the four main types of dementia, Alzheimerís disease (AD) is by far the best known and most common subtype. It accounts for between 60-80% of all dementia cases. It is believed to be the result of the accumulation of beta-amyloid plaques within the brain which result in the progressive death of brain cells and eventual loss of function as the damage spreads to other parts of the brain.
Genetics plays a role in just who is most likely to suffer from AD particularly in the less common early-onset variant (diagnosed in those between the ages of 30-60) of the disease.
While the onset is so gradual that it is at first undetectable, short-term memory loss is by far the most common first sign of the disease often followed shortly by challenges with visuospatial abilities (eg. becoming lost in a familiar environment).
As time goes on, the list of cognitive symptoms mentioned above usually present themselves and are often joined by noncognitive symptoms such as depression, hallucinations, illusions, and assorted behavioural symptoms (physical and verbal aggression, wandering, motor hyperactivity, uncooperativeness,...).
In the end stages of this dreadful disease, patients may present with an absolute inability to communicate in any manner nor display the ability to sit up or track an object with their eyes. Vascular dementia is the second most prevalent form of dementia accounting for about 20% of all cases. It occurs as a result of a lack of blood flow to a region of the brain and the resulting death of the cells in that particular area. Not surprisingly, stroke is the most common cause of this form.
Initial symptoms vary far more than with AD as they depend on both size and location of the damage within the brain. The symptoms can present spontaneously (such as after a major stroke) or may appear to come on gradually if the damage is a result of multiple mini strokes (known as TIAís or transient ischemic attacks).
One way to differentiate this form from AD is that short term memory is not necessarily impaired unless that part of the brain was damaged by the lack of blood flow.
Lewy body dementia (LBD) is caused by the deposit of abnormal protein (known as Lewy bodies) inside the neurons of the brain. LBD accounts for between 5-15% of all dementias.
One way to distinguish LBD from the other forms of dementia is that its symptoms are far more likely to fluctuate on a day to day basis. As such, patientís may display sustained periods of staring into space followed in short order by periods of much greater levels of alertness and awareness.
LBD patients tend to struggle with sleep, memory loss and hallucinations, although the memory loss tends to occur further along in the course of the disease than is seen with AD. The other distinguishing trait of LBD is that more than 80% with this disorder develop parkinsonism and hence struggle with rigidity and bradykinesia (slow movement). As such, this form can be difficult to distinguish from true Parkinsonís disease.
The keys are that with LBD the movement issues occur up to 12 months after the onset of dementia whereas in Parkinsonís the challenges with rigidity come before any dementia that can be associated with that disease.
The fourth type refers to Frontotemporal dementias which is a general term used to describe disorders such as corticobasal degeneration, progressive supranuclear palsy and Pickís disease that affect the fronatal and temporal lobes of the brain. These are all rare in nature and can be distinguished from the other types of dementias by the fact that they tend to rear their ugly heads earlier in life (40-75 years) and are more likely to involve personality changes and behavioural disturbances fairly early into the course of the disease.
Conversely, visuospatial functioning seems to be unaffected even in advance stages of these disorders.
Differentiating between the type of dementia is of benefit so as to inform the caregivers (and the patient) the likely course of the disease but is of limited value unfortunately when it comes to treatment.
Only Alzheimerís has pills that are specifically designed to treat it and these are modestly effective at best. They can serve to delay the progression of cognitive and behavioural deterioration, thereby improving the quality of life for both patients and their caregivers but they do not stop the advancement of the disease so that over time they will inevitably cease to make much of a difference.
As well , of course, not all patientís will respond to these drugs so there are times when they will not positively impact the patient at all. As for the other types of dementia, treatment is strictly supportive meaning that the use of drugs is limited to controlling symptoms that present themselves such as psychosis, depression, sleep disturbances and the like.
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Monday, April 17, 2017