Index
- What is the link between Alzheimer's disease and Down syndrome?
- Characterization of the respective diseases
- Alzheimer's disease
- Down syndrome
- Concrete links between diseases
- Warning Signs of Alzheimer's Disease in People with Down Syndrome (Trisomy 21)
- Links at the level of the molecular mechanism
- The need for assessment for people with trisomy 21
- Assessment of Alzheimer's disease in Down syndrome
- Characterization of the respective diseases
What is the link between Alzheimer's disease and Down syndrome?
Alzheimer's disease and Down syndrome may seem totally different, but there is a certain relationship. This link can be identified either at the level of the molecular mechanism or at the behavioural level. Also, the means of assessing Alzheimer's disease in people with Down syndrome differs from the general population.
Characterization of the respective diseases
Alzheimer's disease
Alzheimer's disease is a chronic disease of the brain whose exact origin is still unknown but to which several factors contribute. It is a dementia in the medical sense of the term. The symptoms that characterize dementia and therefore Alzheimer's are:
- Difficulty in performing some common tasks
- Memory loss
- Decreased ability to judge and reason
- Mood and behavioural changes
There are two types of dementia: primary dementia, which includes Alzheimer's disease, and secondary dementia caused by other diseases. These secondary dementias are the result of treatable illnesses such as depression or thyroid disease. With its insidious onset, the manifestations of Alzheimer's disease remain discreet for a long time. The brain abnormalities accompanying the disease already begin several years before the first symptoms appear. Today, assessment techniques make it possible to diagnose the disease much earlier than in the past.
Down syndrome
Down syndrome is a genetic abnormality manifested by the presence of a supernumerary chromosome on chromosome 21. It is also known as Trisomy 21. The disease causes a delay in intellectual functions and presents several characteristic physical symptoms. Down syndrome is not related to gender, race or nationality. Its exact origin, however, remains unknown to this day. In any case, it is the anomaly causing the most serious learning disabilities in children. The abilities of people suffering from the anomaly vary widely, each with their own difficulties and particularities. Current improvements in health care are reducing infant mortality and increasing the life expectancy of these children. People with the syndrome can now live up to fifty years.
Concrete links between diseases
Warning Signs of Alzheimer's Disease in People with Down Syndrome (Trisomy 21)
Alzheimer's disease and Down syndrome have specific warning signs. In the person with Down syndrome, changes in behaviour and personality are the first signs of Alzheimer's disease. According to researchers, these changes resemble the characteristics of frontotemporal dementia. This is a rare disorder that mainly affects the temporal lobe of the brain. They are associated with personality and behaviour and impair ability to function. Seizures, on the other hand, are also among the other warning signs of the disease. These seizures should not be underestimated, especially in people who have never had them before.
Links at the level of the molecular mechanism
The molecular mechanism of Alzheimer's disease is manifested by the presence of plaques and tangles in the brain. The cleavage of the β-amyloid protein with the precursor of the β-amyloid protein or APP characterizes a plaque. The tangles and the β-amyloid protein make the cell sick and kill it. Researchers have discovered a link between Alzheimer's disease and Down syndrome through this protein. Since people with Down syndrome have an extra chromosome 21, they may have an overproduction of APP. The more APP, the greater the risk of producing the protein β-amyloid. As a result, these people may develop the tangle of plaques characteristic of Alzheimer's disease. However, they may not have all the symptoms of the disease. Alzheimer's disease and Down syndrome differ when Alzheimer's includes other exogenous factors.
The need for assessment for people with trisomy 21
Before the age of 30, it is useful to assess the cognitive and functional abilities of a person with Down syndrome. The goal is to be able to identify any future decrease in this ability. Similarly, regular screening tests for cardiovascular problems and diabetes may also be necessary.
Assessment of Alzheimer's disease in Down syndrome
It is essential to rule out any other disease or possible explanation for the disease beforehand. This step is crucial for the diagnosis of anyone suspected of having dementia. The changes may be the result of depression, trauma or abuse. Alzheimer's disease and Down syndrome are thus different from other diseases in the way they are assessed. This is because the tools the physician uses to assess the general population do not always work. Because they do not take into account people's intellectual abilities and needs, they can misdiagnose. The assessment then requires specific tests such as:
- The Dementia Rating Scale for Down Syndrome (DSDS)
- Le test for Severe Impairment (TSI)
- The Down syndrome Mental State Exam (DSMSE)
- The Dementia Questionnaire for Mentally Retarded Persons (DMR)
