With World Alzheimer’s Day taking place on September 21, and our attention being focussed on this troubling disease, we delve into this often a misunderstood topic.
Clearing up misinformation surrounding the age groups impacted by Alzheimer’s. Degeneration of brain tissue primarily affects people over the age of 65. In these cases, it is known as late-onset Alzheimer’s disease.
It is necessary to point out that the disease has also been reported among people in their 50s, 40s and even 30s. This is known as early-onset Alzheimer’s disease.
People who have been diagnosed with Alzheimer’s will sadly, eventually lose the ability to think, reason and co-ordinate movement. They will ultimately become incapacitated over the course of five to eight years.
While intensive research has gone into studying Alzheimer’s, scientists still do not know the exact cause of this disease. To date, an investigation into the cause has found two primary forms of neural damage or abnormalities which can be linked to the disease and its subsequent progression.
We now look at some of the results found during the research:
Tangled nerve cell fibres (neurofibrillary tangles)
When referencing a microscopic study of a human brain which has died from Alzheimer’s disease, tangled nerve cell fibres are observed in some regions of the brain. (Nerve cell fibres are typically found inside nerve cells.)
As the nerve fibres become tangled, protein deposits called plaques build up in the affected tissue, with a protein called tau being found in the tangles. Scientists are not sure how these neurofibrillary tangles are formed, but they are characteristic of the condition.
Senile or neuritic plaques
These patches are situated outside the nerve cells and are surrounded by dying neurons (nerve cells).
The plaques contain a sticky protein, beta-amyloid, leading to the malfunctioning of nerve cells. This then results in the death of these cells.
The plaques are made of amyloid precursor protein (APP) molecules, which are usually essential components of the brain. Plaques are formed when an enzyme takes APP apart at a specific location and leaves the fragments (beta-amyloid) in brain tissue, where they deposit abnormally.
The presence of neuritic plaques may be linked to a reduction in acetylcholine, an important chemical that is instrumental in relaying messages in the brain.
The association between Down syndrome and Alzheimer’s disease has led scientists to look for genetic factors on chromosome 21. This is the chromosome which is involved in Down Syndrome.
Chromosomes are found in each cell in the body and carry the hereditary information (genes). Other chromosomes that scientists have studied in relation to Alzheimer’s disease include chromosomes 14 and 19.
According to Mediclinic Info Hub, the study of chromosome 19 is the most significant. It was on this chromosome that scientists discovered the ApoE-e4 gene, a well-known marker for heart disease that is commonly found in people who developed Alzheimer’s disease at age 65 years or older.
Studies found the gene was less likely to be found in people who did not have Alzheimer’s disease. These findings led scientists to believe that people with this gene might be more susceptible to Alzheimer’s disease, although it is not a definite indicator.
Currently, there is no cure for Alzheimer’s disease.
However, certain medicines can help improve the patient’s memory and slow the progression of the disease in the early stages. Other forms of medication can alleviate mood changes and other behavioural problems associated with the disease.
One of the main goals of treatment in Alzheimer’s disease is to manage the symptoms as far as possible.
- Aricept (donepezil hydrochloride), Exelon (rivastigmine) and Reminyl (galanthamine) work by slowing the breakdown of acetylcholine, the chemical which helps the neurons communicate with one another. It may help improve memory to some extent in people with mild to moderate Alzheimer’s disease.
- Ebixa (memantine) blocks NMDA glutamate receptors in the brain providing neuroprotective effects from toxic levels of glutamate. It has been shown to slow the deterioration of the illness and to improve activities of daily living.
- Several drugs can alleviate specific symptoms. Antidepressants, anti-anxiety, mood-stabilising and other medications (e.g. antipsychotics) can be prescribed.
However, it is vital to stress that obtaining a diagnosis from a respected doctor is of the utmost importance. This is because treatable conditions, such as hypothyroidism, vitamin deficiency, hypoglycaemia, anaemia and depression have symptoms similar to Alzheimer’s disease.
Information sourced: Mediclinic Info Hub
Previously reviewed by Dr Frans Hugo, MBChB, M.Med Psychiatry
Reviewed by Dr Frans Hugo and Dr Michael Mason (Panorama Psychiatry and Memory Clinic), September 2011.