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Alzheimer's disease belongs to the group of neurodegenerative diseases and is the most common cause of dementia in people over 65 years of age. This disease owes its designation to the German neuropathologist Alois Alzheimer who first described it in 1906 after analyzing the brain of a woman who had died from an unusual mental illness.
Although the main initial clinical manifestation is dementia, which is characterized by the progressive loss of cognitive function, the symptoms of Alzheimer's disease go far beyond that. At the beginning of the disease, there is an insidious impairment of higher intellectual function with changes in mood and behaviour, however, with the progression of the disease, there is severe cortical dysfunction which causes the patient to present disorientation and aphasia (language difficulties). After a few years, in a more terminal phase, the patient becomes profoundly disabled, mute, and immobile.
Alzheimer's disease is mostly idiopathic, that is, cases are sporadic, however, about 5-10% are familial cases. In most sporadic cases, symptoms do not appear before 60 years old. It isn’t known exactly what the risk factors are, however, it is considered that the probable causes are a combination of genetic and environmental factors.
On the other hand, in familial cases, symptoms appear earlier and are associated with genetic alterations.
What happens in the brain that causes Alzheimer's disease?
This disease is characterized by the abnormal accumulation of β-amyloid proteins and tangles of tau protein in the brain. These proteins are toxic to brain tissues causing loss of neurons and connections between neurons. As neurons die, various parts of the brain shrink. Macroscopically, the shrinkage of the brain of individuals with Alzheimer's is visible.
Diagnosis
The diagnosis of this disease consists of a combination of clinical assessment in which the doctor talks to his patient in order to perceive memory changes and, in addition, can talk to the patient's family to investigate possible behaviours that the patient may have. In addition, the pathological evaluation of the brain using imaging allows a more accurate diagnosis of about 80 to 90% of cases. Morphologically and macroscopically, there is cortical atrophy with enlargement of the cerebral sulci, the hippocampus, amygdala, and entorhinal cortex are the most affected areas in this disease. Microscopically, the changes observed, which are the basis of histological diagnosis, are neuritic or senile plaques, which are due to the accumulation of β-amyloid protein, and the presence of neurofibrillary tangles, which are due to the accumulation of tau protein.
Treatment
So far there is no cure for this disease, there are simply some treatments that help to slow down the rapid progression of the disease. Behavioural therapy is the most recurrent to keep the patient physically and mentally active.
Precision medicine [adapts the best treatment for each specific person] is increasingly gaining strength and may in a few years be the solution for many patients with this disease, especially in cases of familial Alzheimer’s.
Being aware of the signs and maintaining a healthy and active life, physically and mentally is the best way to prevent this disease!
Want to know more?
Well, we recommend the book Alzheimer the truth of the disease of the century written by Pr. Bruno Dubois, an incredible book that explains how Alzheimer's is diagnosed and the current treatments available. A book that will change the way we see this disease.
References
1. A, K., J, S., A, G., & JW, T. (2022). Alzheimer Disease. StatPearls, 1–27. https://pubmed.ncbi.nlm.nih.gov/29763097/
2. Alzheimer’s Disease Fact Sheet | National Institute on Aging. (n.d.). Retrieved September 17, 2022, from https://www.nia.nih.gov/health/alzheimers-disease-fact-sheet
3. Castanho, I., & Lunnon, K. (2019). Epigenetic processes in Alzheimer’s disease. Chromatin Signaling and Neurological Disorders, 153–180. https://doi.org/10.1016/B978-0-12-813796-3.00008-0
4. De Loof, A., & Schoofs, L. (2019). Alzheimer’s Disease: Is a Dysfunctional Mevalonate Biosynthetic Pathway the Master-Inducer of Deleterious Changes in Cell Physiology? OBM Neurobiology, 3(4), 1–1. https://doi.org/10.21926/OBM.NEUROBIOL.1904046
5. Foidl, B. M., & Humpel, C. (2019). Chronic treatment with five vascular risk factors causes cerebral amyloid angiopathy but no Alzheimer pathology in C57BL6 mice. Brain, Behavior, and Immunity, 78, 52–64. https://doi.org/https://doi.org/10.1016/j.bbi.2019.01.009
6. How Alzheimer’s Changes the Brain - YouTube. (n.d.). Retrieved September 17, 2022, from https://www.youtube.com/watch?v=0GXv3mHs9AU&t=120s&ab_channel=NationalInstituteonAging
7. Messier, C. (2005). Impact of impaired glucose tolerance and type 2 diabetes on cognitive aging. Neurobiology of Aging, 26(1, Supplement), 26–30. https://doi.org/https://doi.org/10.1016/j.neurobiolaging.2005.09.014
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