Alzheimer's disease

 

Alzheimer's disease definition

Alzheimer's disease is the most common form of dementia.

Typical of old age, this condition is a neurodegenerative syndrome, which involves a gradual and irreversible loss of cognitive functions.

The most characteristic symptoms of Alzheimer's consist of memory deficits, language problems, personality changes, lack of initiative, confusion, disorientation, and loss of reasoning and judgment.

Experts believe that genetic and environmental factors, plus a certain style and sometimes familiarity with the disease, contribute to causing Alzheimer's disease.

The evidence is clear on the pathophysiology of this form of dementia: the patient's brain undergoes a process of atrophy and at an extra- and intracellular level it accumulates protein aggregates, which seem to affect the survival and function of neurons.

The diagnosis of Alzheimer's disease is complex; In fact, numerous investigations are needed, including physical examination, anamnesis, neurological examination, cognitive and neuropsychological tests, laboratory tests of various kinds, and imaging diagnostics ( brain CT and magnetic resonance imaging of the brain).

Currently, Alzheimer's is not curable. However, patients can count on various symptomatic treatments, which can alleviate the symptoms and slow down the inexorable cognitive deterioration typical of the disease.

Alzheimer's disease: what is it?

Alzheimer's disease is a neurodegenerative disease that involves a gradual and irreversible loss of cognitive functions.

Also known as Alzheimer's disease or simply Alzheimer's, Alzheimer's disease is a form of dementia that usually occurs in old age, but can also affect young individuals between the ages of 30 and 60 ( early-onset Alzheimer's or juvenile Alzheimer's ).

Without going into too much detail, Alzheimer's is known to cause memory deficits, language problems, personality changes, lack of initiative, confusion, disorientation, loss of reasoning and judgment, etc.

Alzheimer's disease compromises the patient's life expectancy: complications of the disease in its most advanced stages can be fatal.

 

Alzheimer's: why is it called that?

Alzheimer's disease owes its name to the German neuropathologist and psychiatrist Alois Alzheimer, who is credited with having first described the disease in 1906.

 

Alzheimer's observations were the result of studies conducted on an elderly woman, who died of a then-unknown mental illness, who had abnormal brain tissue.

 

Did you know that ...

Although Dr. Alzheimer's made his observations in 1906, Alzheimer's disease only became known by this name in 1910.

 

Epidemiology

How common is Alzheimer's disease?

In 2020, the World Health Organization (WHO) reported that there were approximately 50 million people with dementia worldwide.

Now, taking into account that Alzheimer's disease accounts for 60-70% of all forms of dementia, this disease, in the year reported above, had between 30 and 35 million patients.

 

As a result of the lengthening of the average life span of the human being, experts believe that the number of people with Alzheimer's and, more generally, those with dementia is destined to increase progressively.

This forecast is also confirmed in past data: in 2010, there were 36 million people with dementia in the world, therefore 14 million fewer than in 2020.

 

Alzheimer's disease and the number of new cases per year

Also according to what is reported by the WHO, every year, in the world, there are 6 to 7 million new cases of Alzheimer's (10 million new cases of dementia in total).

 

Alzheimer's disease and age

Alzheimer's disease is a typical disease of old age: most patients are over 65 years old.

 

It should be noted that from the age of 65 the risk of Alzheimer's progressively increases, confirming that aging plays a pivotal role in the onset of the disease.

 

As anticipated, there is also a form of juvenile Alzheimer's (early-onset Alzheimer's); uncommon, this condition affects people between the ages of 30 and 60 and constitutes 5-10% of all Alzheimer's cases.

 

Alzheimer's disease and life expectancy

Alzheimer's disease shortens the life expectancy of the people who suffer from it.

Statistics suggest that, generally, from the time of diagnosis, the disease takes between 3 and 10 years to cause death (a longer life expectancy is typical of "younger" patients).

Causes

Alzheimer's Disease: What Are the Causes?

The precise causes of Alzheimer's are still unclear; undoubtedly, the complexity of the human brain makes it difficult to study and understand.

 

At the moment, experts believe that a combination of various factors, including genetics, environmental factors, familiarity, and lifestyle, are at the root of the disease.

 

Based on the research conducted to date, this set of factors would seem capable of altering the patrimony of some brain proteins, to the point of having toxic effects on the brain itself.

 

Alzheimer's disease: pathogenesis

On magnetic resonance and PET investigations, and post-mortem examination, the brain of an Alzheimer's patient shows various abnormalities.

 

From the macroscopic point of view, a phenomenon of cerebral atrophy is evident; this means that there has been a reduction in brain tissue, following cell necrosis or a shrinking of nerve cells.

In this regard, it is particularly interesting to note that atrophy is particularly accentuated in the hippocampus and amygdala, the main brain areas involved in the ability to memorize.

 

From the microscopic point of view, however, the presence of protein aggregates is commonly found, both outside (extracellular) and inside (intracellular) of neurons.

Outside the neurons, the aggregates (or plaques ) of beta-amyloid peptide (or simply Aβ ) are reported, while inside the neurofibrillary clusters of hyperphosphorylated tau protein are characteristic.

 

The precise role of protein aggregates has not yet been fully clarified; however, they believe that beta-amyloid plaques and clusters of tau protein interfere with normal interneuronal (ie between neurons) nerve transmission and are capable of causing nerve cell death.

Early Onset Alzheimer's: the Causes

In early-onset Alzheimer's, genetic factors and family history appear to play a greater role than in the more common form of Alzheimer's.

 

Indeed, for some patients, the disease is the result of inherited genetic mutations.

 

According to some studies, 60% of people with juvenile Alzheimer's would have a positive family history of Alzheimer's disease, and 13% of these would result from an inherited genetic mutation.

 

This evidence, however, does not exclude the possibility that juvenile Alzheimer's can also arise in people without a particular familiarity with the disease.

 

Alzheimer's and Genetics: the genes involved in the disease

The research has identified some genes whose mutation is associated with Alzheimer's disease; among these genes, we note:

 

APOE-e4, located on chromosome 19 and involved in the formation of apolipoprotein E.

Alterations of APOE-e4 are common in people with the traditional form of Alzheimer's;

APP, located on chromosome 21 and coding for the amyloid precursor protein, PSEN1, located on chromosome 14 and coding for presenilin 1, and PSEN2, located on chromosome 1 and coding for presenilin 2.

Unlike the previous case, alterations of APP, PSEN1, and PSEN2 are commonly found in people with family-related juvenile Alzheimer's.

Risk factors

Alzheimer's: Who Is Most at Risk?

Research has shown that some specific factors increase the likelihood of getting Alzheimer's; among these risk conditions, the most significant are:

 

Advanced age. It is undoubtedly the most important contributing factor. Proof of this is the fact that most of the patients are over the age of 65.

The age of 65 is a very significant time limit for Alzheimer's: some interesting studies have shown that, after this age, the probability of developing the disease doubles every 5 years.

Aging involves changes in the structure of DNA and cells in general (including nerve cells); moreover, it weakens the natural cellular repair systems and promotes hypertension. All these significant changes appear to underlie the risk associated with old age.

Familiarity and genetic predisposition. This issue has already been discussed above.

It is a fact that the risk of developing Alzheimer's is higher for people with a first-degree relative (parent or sibling) who has the same disease.

The sex . Epidemiological studies have shown that women are more likely to develop Alzheimer's disease; from these same studies, however, it also emerged that sick women would live longer than sick men.

The risk associated with sex is probably justified by hormonal factors.

The lifestyle. Important research has shown that the same risk factors for heart disease are also associated with an increased likelihood of developing Alzheimer's.

Among these factors are above all: aforementioned hypertension, sedentary lifestyle, obesity, cigarette smoking, hypercholesterolemia, and type 2 diabetes.

Down syndrome. Carriers of Down syndrome are particularly prone to developing Alzheimer's. This trend seems to be linked to the presence of the third chromosome 21 and, consequently, to a third APP gene encoding the amyloid precursor protein (remember that APP gene mutations are associated with the onset of juvenile Alzheimer's).

Cognitive decline (or decline ) related to old age. This is a normal evolutionary process that the brain undergoes during aging.

Trauma to the head. Some studies suggest that a medical history of severe head trauma increases the risk of developing a form of dementia, which in many cases is Alzheimer's disease.

Symptoms and Complications of Alzheimer's disease

Alzheimer's disease is a condition characterized by the progressive death of brain nerve cells; this phenomenon implies that the resulting symptoms - which consist of neurological manifestations - are destined to undergo, over time, a gradual and inexorable worsening.

 

It is customary to divide the evolution of symptoms associated with Alzheimer's disease into three phases (or stages):

 Diagnosis of Alzheimer's disease

The early symptom stage (or early stage of Alzheimer's);

The phase of the intermediate symptoms (or the intermediate phase of Alzheimer's);

The stage of final symptoms (or late or late stage of Alzheimer's).

The early stage of Alzheimer's: the first symptoms

The early stage of Alzheimer's is the time of the disease when the first symptoms appear.

 

The onset manifestations of Alzheimer's typically consist of:

 

Small short-term memory problems ( anterograde amnesia )

Apraxia, i.e. inability to perform common actions such as whistling;

Sporadic personality changes

Occasional lack of judgment

Repeat the same question several times;

Slight  difficulties in the language (principle of aphasia ), the calculation (principle of acalculia), reasoning, and understanding of new concepts;

Tendency to passivity and lack of initiative,

The patient forgets recent events or conversations in which he participated; loses items; does not remember the names of places and things (anomia); struggles to recognize objects and things that were previously known ( agnosia ); begins to lose the faculties of writing and reading.

 

Intermediate Stage of Alzheimer's: Intermediate Symptoms

The intermediate stage of Alzheimer's is characterized by a worsening of the initial symptoms, in particular, short-term memory problems and language and calculation difficulties; moreover, it leads to the appearance of new ailments.

 

New manifestations of this second stage of the disease include:

 

Obvious loss of part of the cognitive abilities, from reasoning and learning to judgment skills;

Long-term memory problems

Emotional instability, mood swings, depression, anxiety, and/or agitation;

Obsessive, repetitive, and/or impulsive behaviors;

Episodes of delirium and paranoid behavior (without any reason, the patient is suspicious of the people around him, to the point of sometimes proving to be aggressive);

Space-time confusion (or disorientation), with the patient struggling to realize where he is, to say with certainty the day of the week, etc;

Difficulty in quantifying distances approximately;

Auditory hallucinations;

Disturbed sleep.

At this stage of Alzheimer's, it is very common for the patient to begin to need the support of other people to help him in daily life; for example, they may need support in washing, dressing, or using the bathroom.

 

Final Phase of Alzheimer's: The Final Symptoms

The final stage of Alzheimer's is the moment of the disease in which the now complete symptomatological picture worsens further and becomes incompatible with a normal life.

 

Cognitive abilities are now completely compromised: this is demonstrated by the degree of extreme severity reached by memory deficits and language difficulties.

Episodes of delirium and paranoia are increasingly common, as are mood swings.

In addition, new issues appear, including:

 

Difficulty swallowing

Loss of control of bowel and bladder function ( incontinence )

Loss of motor control, with the patient walking and moving less and less;

Weight Loss.

At this stage of the disease, the person with Alzheimer's becomes completely unable to take care of himself, therefore he needs someone daily to help him eat, wash, move, etc.

 

Alzheimer's Disease: Complications

The severe impairment of memory and language skills induced by advanced Alzheimer's means that the patient is unable to:

 

Communicate any pain ;

Communicating the symptoms of another disease presumably caused by old age;

Independently follow a therapeutic plan;

Communicate the side effects produced by a drug taken to control some disease.

All these problems complicate the possibility of early diagnosis and treatment of other pathologies, sometimes even very serious ones, which could arise especially considering the advanced age of the patient.

 

Furthermore, with the onset of swallowing, walking, incontinence, and intestinal control problems, the patient tends to develop:

 

Inhaled pneumonia and bronchopneumonia, and other respiratory tract infections. Due to the difficulty in swallowing, they have important repercussions on the patient's state of health.

Malnutrition and/or dehydration. These are also due to swallowing difficulties.

Constipation or diarrhea. They depend on the loss of control of intestinal functions.

Fractures and bedsores. They are due to walking problems.

Alzheimer's disease: when do you die?

Alzheimer's leads to death when it reaches its most advanced stage, therefore when it has seriously compromised the cognitive faculties and more.

 

The main cause of death is respiratory complications induced by inhalation pneumonia and bronchopneumonia that the patient tends to develop as a result of swallowing problems.

 

As stated in an earlier passage of the article, Alzheimer's disease takes 3 to 10 years to reach its final stage and causes the individual to die.

Being mostly elderly, many times people with Alzheimer's suffer from other typical pathologies of aging, such as hypertension, heart disease, etc.

Consequently, it happens quite frequently that the Alzheimer's patient dies earlier from a complication of the aforementioned conditions than from the more advanced form of dementia.

Senile Dementia: When to Worry?

For the elderly individual, manifesting some too many amnesias, experiencing unusual calculation difficulties and having language problems, and understanding new concepts must represent an alarm bell, such as to lead to consulting a doctor (to understand it deals with early Alzheimer's or another condition) and to ask for support from family members.