Many people, especially the elderly, are afraid of developing Alzheimer’s disease. But what is it exactly?
What is Alzheimer’s disease?
Alzheimer’s disease, a condition sometimes referred to in everyday speech as simply »Alzheimer’s«, is named after the German neuropathologist Dr Alois Alzheimer. In 1906, he described for the first time an »unusual disease of the cerebral cortex« in a patient whose symptoms were accompanied by rapid mental degeneration. This form of dementia concerns a degenerative disease of the brain, in which communication between nerve cells no longer functions properly and these cells gradually die off. The exact cause of this loss of nerve cells and cell function has still not been conclusively explained today. What is certain, however, is that the affected brain tissue contains abnormal protein deposits known as beta-amyloid plaques. There is also a chemical change in the tau proteins, whose fibres (known as tau fibrils) accumulate in the nerve cells and destroy them over time.[1]
Alzheimer’s disease is the most common form of dementia : Some 60 to 70 per cent of the over 55 million patients with dementia suffer from Alzheimer’s disease[2]. Although neither Alzheimer’s disease nor dementia are a normal part of ageing, Alzheimer’s disease is increasingly likely to occur with age, with women more likely to be affected than men. Around 1% of the entire population suffer from Alzheimer’s disease. As many as 5 to 10% of persons over 65 and around 30% of persons over 80 are affected by Alzheimer’s disease.
Symptoms of Alzheimer’s disease
Alzheimer’s disease progresses slowly. Depending on the stage of the disease, symptoms may include memory loss, disorientation, speech problems, difficulties performing familiar activities and personality changes. These symptoms may vary in severity and increase as the disease progresses. As a result, patients are no longer able to manage everyday life independently and are increasingly reliant on support. The quality of life of patients with the disease as well as their relatives is significantly reduced as a result.
Alzheimer’s disease or dementia?
The typical dementia symptoms include memory problems. But what distinguishes Alzheimer’s disease from other forms of dementia? In general, it can be said that Alzheimer’s disease concerns a specific (and is the most common) type of dementia. Other common types of dementia include vascular dementia, frontotemporal dementia (FTD) and Lewy body dementia . These are distinguished according to factors such as their frequency, cause, progression and the average age of developing Alzheimer’s disease.[3]
Frontotemporal dementia (FTD)
This, sometimes hereditary, form of dementia is estimated to affect 3 to 9% of dementia patients, making it considerably rarer than Alzheimer’s disease. Around 60% of all patients with FTD are diagnosed between the ages of 45 and 64. This form is characterised by the death of nerve cells in what are known as the frontal and temporal lobes of the brain. Frontotemporal dementia has symptoms that are sometimes clearly distinguishable from Alzheimer’s disease: Patients suffer to a lesser extent from memory loss and to a greater extent from behaviour and personality changes.
Lewy body dementia
Since it emerged after the death of actor Robin Williams that he had suffered from Lewy body dementia, public awareness of this form of neurodegenerative dementia has increased. This form of dementia usually occurs from the age of 50 onwards. Clumps of proteins, known as Lewy bodies, accumulate in the nerve cells of the brain. Lewy body dementia is characterised by signs including memory problems and psychotic symptoms, sleep problems, sharp variations in attention and mental capacities, and sometimes movement disorders.
Vascular dementia
As the name already suggests, this second most common form of dementia affects the blood vessels. Multiple »mini-strokes« cause circulation problems in the brain, which leads to damage or death of nerve cells. This in turn leads to mental and other impairments that resemble Alzheimer’s disease. Vascular dementia usually occurs in very old age, but may also occur in conjunction with Alzheimer’s disease. The risk factors are similar to those for strokes, specifically high blood pressure, overweight, high cholesterol, diabetes, heart disease and smoking.
Is it possible to prevent Alzheimer’s disease?
There is currently no cure for Alzheimer’s disease. But what can be done to prevent Alzheimer’s disease? Ultimately, we know that brain changes in patients with Alzheimer’s disease often start many years before the appearance of the first symptoms. Despite intensive research, no reliable prevention strategy is yet known. However, there are indications that physical activity, healthy diet, avoiding being overweight, measures to reduce blood pressure and cholesterol[2], targeted brain training or mental stimulation and maintaining close social connections may reduce the risk of cognitive impairment[4].
Current approaches to treating Alzheimer’s disease
Although there is currently no cure for Alzheimer’s disease, treatment options are available to alleviate the accompanying phenomena and symptoms. At present, doctor’s treating patients rely primarily on three categories of Alzheimer’s drugs:
- Anti-dementia drugs (specifically acetylcholinesterase inhibitors and glutamate antagonists)
- Antidepressants
- Antipsychotics (neuroleptics)[5]
Herbal medicines are also used for patients with Alzheimer’s disease, such as Ginkgo biloba[6].
Outlook: Current status of Alzheimer’s disease research
As stated earlier, the cause of Alzheimer’s disease has not yet been fully explained. This presents researchers with a considerable challenge, particularly because Alzheimer’s disease initially does not cause any symptoms, although brain changes have already occurred.
Dr Alois Alzheimer had already described the characteristic deposits, which enabled research to focus primarily on amyloid-beta and tau proteins. This also included the monoclonal antibody medication aducanumab (Aduhelm), authorised in the USA in 2021 and taken off the market again in 2024. Lecanemab (Leqembi), which was authorised by the FDA in 2023, and the not yet authorised substance donanemab also target these proteins[7]. Sarcatinib, a substance that was originally developed as a potential cancer drug, is also among other drug-based therapy being researched in order to establish whether it can slow down or prevent the destruction of nerve cells.
Other research is concerned with the role of chronic inflammation, insulin resistance, a possible relationship between heart disease and hormones or hormone replacement therapy[8] in relation to Alzheimer’s disease.
A method that is also being researched and applied is non-invasive brain stimulation (NIBS) procedures , which are already available to patients to some extent and are intended to stimulate specific areas of the brain through the skull. These include transcranial magnetic stimulation (TMS) and transcranial pulse stimulation (TPS). TPS, which is performed with the NEUROLITH system, has been specially approved as a treatment option for patients with Alzheimer’s disease.
References
- (AFI), A.F.I.e.V. Alzheimer: Ursachen und Veränderungen im Gehirn. Available from: https://www.alzheimer-forschung.de/alzheimer/wasistalzheimer/veraenderungen-im-gehirn
- 15 March 2023; Available from: https://www.who.int/news-room/fact-sheets/detail/dementia
- Alzheimer’s & Related Dementias. Available from: https://www.alzheimers.gov/alzheimers-dementias
- Can Alzheimer’s Disease Be Prevented?; Available from: https://www.alz.org/alzheimers-dementia/research_progress/prevention
- Alzheimer-Medikamente im Überblick: Medikamentöse Behandlung der Alzheimer-Krankheit. Available from: https://www.alzheimer-forschung.de/alzheimer/behandlung/medikamentoese-behandlung
- Yang, G., et al., Ginkgo Biloba for Mild Cognitive Impairment and Alzheimer's Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Curr Top Med Chem, 2016. 16(5): p. 520-8.
- Warum die Suche nach einem Medikament so schwierig ist: Demenz- und Alzheimer-Forschung aktuell. Available from: https://www.alzheimer-forschung.de/forschung/aktuell/
- Alzheimer's treatments: What's on the horizon? 2024 Feb. 13, 2024; Available from: https://www.mayoclinic.org/diseases-conditions/alzheimers-disease/in-depth/alzheimers-treatments/art-20047780
