The 9 types of Alzheimer's disease (classified and described)

Alzheimer's disease is a neurodegenerative condition in which the patient suffers from problems with memory, as well as symptoms such as confusion, mood swings, changes in personality and behaviors aggressive.

Patients diagnosed with this disease become very dependent on their social environment, since as it goes As the disease progresses, their ability to do the simplest and most everyday tasks fades as well as the memories that made up their life.

Although most patients with this dementia show the same symptoms, there are different types of Alzheimer's based on severity and other criteria that we will explore below.

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What is Alzheimer's disease?

Alzheimer's disease is a neurodegenerative condition that brings with it multiple cognitive and behavioral symptoms. This disease usually begins with minor memory loss and confusion, evolving to total memory loss, decision-making problems and severe difficulties in performing daily tasks **.

Added to these symptoms, there are also changes in the patient's personality along with depressive symptoms, mood swings, social isolation and aggressiveness.

Around 50 million people worldwide are believed to be living with Alzheimer's disease today. The number of cases worldwide is expected to reach 131 million by 2050. This disease is one of the top ten causes of death in most developed countries, since the population is aging and this neurodegenerative condition is more common when they are over 65 years of age. In the particular case of Spain, there are about 800,000 cases of the disease.

Although age is considered a risk factor for Alzheimer's, the symptoms associated with this disease are not simply the result of aging. Behind the appearance, severity and progression of this neurodegenerative disease also play a key role genetics and lifestyle, although it is not known exactly to what extent and in certain subtypes of Alzheimer's.

From the neurosciences, many theories have been proposed to explain the reason for the changes that occur at the brain level during the course of Alzheimer's disease. Despite having a variety of explanatory hypotheses, they do agree that there are two distinctive features of this disease: neurofibrillary tangles and senile plaques.

Neurofibrillary tangles are abnormal structures made up of the Tau protein, a substance that makes up the cell cytoskeleton.

Senile plaques are structures composed of beta-amyloid protein aggregates and cause interference in cell communication, eventually causing the death of neurons.

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What types of Alzheimer's are there?

There is a diversity of opinions in the scientific community not only when it comes to talking about the different types of Alzheimer's that it seems there is, but there is also the debate as to whether Alzheimer's can be classified as a dementia on its own or as the cause of a. There is no doubt that it is a brain disease, but there are those who consider that more than being a type of dementia, it would be the biological cause of what causes dementia, manifested in cognitive and behavioral symptoms.

Experts who consider Alzheimer's disease a genuine dementia classify it along with the other types of neurodegenerative diseases in which there is cognitive and behavioral impairment:

• Mild cognitive impairment
• Creutzfeldt-Jakob disease
• Lewy body dementia
• Vascular dementia
• Brain damage associated with alcoholism
• Early dementia
• Frontotemporal dementia
• HIV-associated cognitive impairment

According to current knowledge about Alzheimer's disease, it can be classified into different types taking into account as criteria the degree of severity, the type of inflammatory response and the onset or trigger that causes the disease.

According to severity

These are actually phases that a person with this neurodegenerative condition usually goes through, being the normal thing to go from mild to severe Alzheimer's. Diagnosis is crucial to control the disease, since the sooner the patient is diagnosed with this type of dementia, the better chance there is to treat it effectively and prevent the symptoms from progressing quickly.

Depending on the intensity of the typical symptoms of Alzheimer's disease, we talk about the following types of Alzheimer's.

1. Mild Alzheimer's

In mild Alzheimer's (Mild Alzheimer's) there are signs of cognitive decline. The patient has slight problems when doing daily tasks, such as paying bills, putting on the washing machine, driving, working ...

Because these symptoms are not too conspicuous or severe, the patient who is in this stage of Alzheimer's disease continues to function with some degree of difficulty, but without requiring help from nobody. It will take a little longer for him to carry out tasks that he used to do with agility and speed.

2. Moderate Alzheimer's

In Moderate Alzheimer's there is already great neuronal damage, which makes the symptoms of the disease become more intense. The patient suffers more severe episodes of confusion and, due to greater memory loss, begins to require more and more help until becoming a dependent person.

Although the patient may remain physically agile, not being able to carry out the simplest routine tasks is dangerous to leave him alone or unsupervised. What's more, may suffer from hallucinations and failure to process sensations, and show symptoms of a delirium, mood swings and aggressive behaviors.

3. Severe Alzheimer's

As the neurofibrillary plaques and tangles of Tau protein begin to spread throughout the brain, the nerve cells begin to die. This results in a reduction in brain tissue. Patients with severe Alzheimer's often end up in bed and even lose the ability to speak.

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According to the inflammatory response

Alzheimer's is categorized into three types based on the inflammatory response.

1. Inflammatory Alzheimer's

In addition to presenting the characteristic cognitive and behavioral symptoms of the disease, inflammatory Alzheimer's has a distinctive feature of a high ratio of serum albumin to globulin and a high level of C-reactive protein in response to inflammation, characteristic biomarkers of this physiological process at the brain level.

2. Non-inflammatory Alzheimer's

Non-inflammatory Alzheimer's does not present high accumulations of biomarkers associated with inflammation. However, there may be other typical metabolic alterations associated with this condition, such as neurofibrillary plaques and tangles.

3. Cortical Alzheimer's

Cortical Alzheimer's is caused by a deficit in zinc levels in various regions of the brain. Although there is no inflammatory response associated with this subtype, this causes alterations in the normal functioning of the brain which give rise to the characteristic symptoms of the disease of Alzheimer's.

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Classification according to the onset and what triggers the disease

It is considered that there are two types of Alzheimer's depending on the age at which it appears, plus a third type in depending on whether it is suspected that there could be heritability between family members to present this dementia.

1. Early Alzheimer's

We say that Alzheimer's is precocious (early-onset Alzheimer's) when it is diagnosed before reaching 65 years of age. These are very rare cases, occurring in only 5 out of every 100 Alzheimer's patients, and the first symptoms can occur as early as 40 or 50 years.

Various factors have been considered to explain the appearance of early Alzheimer's, although it is believed that the most important would be a defect in chromosome 14. People with Down syndrome are prone to this type of Alzheimer's.

2. Late Alzheimer's

Most cases of Alzheimer's present the disease after reaching 65 years of age, being called late Alzheimer's (Late-onset Alzheimer's). This type of Alzheimer's is the most common, accounting for about 95% of cases of people with the disease.

It is not known exactly what the genetic trigger behind the appearance of Alzheimer's is late, although it is considered that there would be a combination of genetic and environmental factors (epigenetic).

The lifestyle and the experiences throughout it influence the possibility of suffering from Alzheimer's. Risk factors are having a stressful life, consuming drugs, smoking, alcoholism, having a poorly varied and healthy diet, sedentary lifestyle and being cognitively not very active.

Although it cannot be said that Alzheimer's is a 100% preventable condition, it is true that maintaining a healthy lifestyle, exercising, drinking a healthy diet, avoiding the consumption of harmful substances and putting our brain to the test can serve to prevent Alzheimer's and its early appearance.

3. Familial Alzheimer's disease

The existence of another subtype of Alzheimer's disease called familial (familial Alzheimer's disease or FAD in English) has been raised. This condition would be extremely rare, occurring in 1 of every 100 patients with this neurodegenerative dementia.

A person can only be diagnosed with FAD if he has a specific genotype of the disease, that is, that there is a specific gene in her family for Alzheimer's and that he or she has it.

Thanks to this, it is possible to detect if a family member could have Alzheimer's through an analysis genetic to see if she has the gene that causes the disease, being possible to calculate the exact risk of suffering this dementia.