Alzheimer’s disease: causes, symptoms, treatment and prevention

A neurodegenerative disease that affects many people in their senescence.

Cancer, HIV/AIDS and dementias are some of the disorders that are of most concern today in the Western population, being some of the most frequent disorders that still do not have an effective solution or treatment.

Within the group of dementias, the best known is dementia caused by Alzheimer's disease..

Alzheimer's disease: general definition

Alzheimer's disease is one of the most common and well-known neurodegenerative diseases. It is a chronic and currently irreversible disorder of unknown causes that causes a progressive deterioration of the sufferer's mental faculties.. Initially it acts only at the level of the cortex, but as the deterioration progresses it also affects the subcortical level. With an insidious onset, the first lesions appear in the temporal lobe and later spread to other lobes such as the parietal and frontal lobes.

Currently, its diagnosis is only considered completely definitive after the death of the patient and the analysis of his tissues (before death, the diagnosis is considered only probable), although as neuroimaging techniques advance, a more accurate diagnosis becomes possible. The course of Alzheimer's disease causes a homogeneous and continuous cognitive deterioration.The average duration of the disease is between eight and ten years.

Typical symptoms

• To learn more about the symptoms: "The first 11 symptoms of Alzheimer's disease (and their explanation)".

One of the most characteristic and well-known symptoms is memory loss, which usually occurs gradually. First of all, recent memory is lost, and as the disease progresses, aspects and elements that are more and more distant in time are forgotten. Attention span, judgment and the ability to learn new things also diminish.

Like most cortical dementias, Alzheimer's disease is characterized by a progressive loss of functions that occur especially in three areas, forming what has been called aphasia-apraxo-agnostic syndrome. In other words, throughout the course of the deterioration, the patient loses the ability to speak (anomia or difficulty in remembering the names of things is very typical), to perform sequential actions or even to recognize external stimuli, culminating in a state of mutism and immobility. The presence of falls, sleep and eating disturbances, emotional and personality disturbances, and loss of smell are also common in those with Alzheimer's disease. and loss of sense of smell are also common in Alzheimer's sufferers.

Over time, the subject tends to become disoriented and lost, to have carelessness and strange and careless behavior, to forget the value of things and even ends up being unable to recognize loved ones. As the disease progresses the subject gradually loses his autonomy, depending over time on the care and management of external agents.

Statistically, the average age at which Alzheimer's disease begins to appear is around 65 years of age, with its prevalence increasing as age increases. It is considered early-onset or presenile if it begins before the age of 65, and senile or late-onset if it occurs after that age. The younger the age of onset, the worse the prognosis, with symptoms progressing more rapidly.

Deterioration process: stages of the disease

As mentioned above, Alzheimer's disease causes a progressive deterioration of the patient's mental functions. This progression can be observed throughout the three phases into which the process of degeneration has been differentiated.

In addition to these phases, it should be taken into account that sometimes there may be a period of time prior to the onset of the disorder in which the individual suffers a deterioration of mental functions. when the individual suffers a mild cognitive impairment (generally of the amnesic type).

First phase: Onset of problems

In the early stages of the disease, the patient begins to experience small memory deficits. He/she has difficulty remembering what he/she has just done or eaten, as well as retaining new information (in other words, he/she suffers from anterograde amnesia). Another particularly typical symptom is anomia or difficulty remembering the names of things despite knowing what they are.

Judgment and problem-solving abilities are also compromised, with less performance in work and daily activities.and less performance in work and daily activities. Initially the patient is aware of the onset of limitations, and depressive and anxious symptoms such as apathy, irritability and social withdrawal often appear. This first phase of Alzheimer's disease can last up to four years.

Second phase: Progressive loss of abilities

The second phase of Alzheimer's disease is characterized by the onset of aphasia-apraxio-agnostic syndrome, together with the onset of amnesia.and the onset of retrograde amnesia. That is, the subject begins to have problems in understanding and uttering language beyond anomia, as well as to have severe difficulties in performing sequenced activities and in recognizing objects, people and stimuli, in addition to beginning to have problems in remembering past events (so far memory losses refer mainly to events that have just happened and were not retained).

The patient needs supervision and is not able to carry out instrumental activities, but may be able to perform basic activities such as dressing or eating on his or her own. There is usually temporo-spatial disorientation, and it is not uncommon to get lost.

Stage Three: The advanced stage of Alzheimer's disease

During the third and final stage of the disease, the individual's deterioration becomes especially intense and evident. Episodic memory loss may go back to childhood. There is also loss of semantic memory. The subject ceases to recognize his relatives and loved ones and is even unable to recognize himself in an image or a mirror. and is even unable to recognize himself in an image or a mirror.

They usually have an extremely severe aphasia that can end in total mutism, as well as incoordination and gait disturbances. There is a loss of total or almost total autonomy, depending on external caregivers for survival and not being able to survive on their own, and basic daily living skills are lost, having total dependence on external caregivers. Episodes of restlessness and personality alterations are frequent.

Hyperphagia and/or hypersexuality, lack of fear before aversive stimulation and episodes of anger may also appear.

Neuropsychological features

Dementia caused by Alzheimer's disease causes a series of effects in the brain that eventually leads to symptoms.

In this regard the progressive reduction of the level of acetylcholine in the brain, one of the main brain neurotransmitters involved in neuronal communication and which influences aspects such as memory and learning.one of the main brain neurotransmitters involved in neuronal communication and which influences aspects such as memory and learning. This decrease in acetylcholine levels causes a progressive degradation of brain structures.

In Alzheimer's disease, the degradation of structures begins in the temporal and parietal lobes, progressing throughout the course of the disorder towards the frontal lobe and gradually towards the rest of the brain. Over time, neuronal density and mass are reduced, and the ventricles dilate to occupy the space left by neuronal loss.

Another aspect of great relevance is the presence in the neuronal cytoplasm of neurofibrillary tangles and beta-amyloid plaques, which hinder synaptic processes and cause a weakening of synapses.

Unknown causes

Research into this type of dementia has attempted to provide an explanation as to how and why Alzheimer's disease arises.. However, there is still no evidence as to why it appears.

At the genetic level, the involvement of mutations in the APP gene, of the amyloid precursor protein, as well as in the ApoE gene, linked to the production of proteins that regulate cholesterol, is suspected.

The decrease in the level of cerebral acetylcholine causes the degradation of the various structures, and pharmacological treatments are based on combating this reduction. A cortical atrophy of temporoparietal onset appears, which eventually generalizes to the rest of the nervous system.

Risk factors

The causes of Alzheimer's disease remain unknown to this day. However, there are a large number of risk factors that must be taken into account when it comes to prevention.

One of the factors to be taken into account is age.. Like most dementias, Alzheimer's disease tends to appear after the age of 65, although there are cases of even earlier onset.

The level of education, or rather, the individual's mental activity, also plays a role. The greater the mental exercise, the greater the resistance and strength of neuronal connections. However, although this effect is positive since it delays the progression of the disease, it can make it difficult to identify the problem and its treatment.

Another factor is the family history. Although Alzheimer's disease is not usually transmitted genetically (except for some specific variant), it is true that almost half of the individuals with this problem have a family member with this disorder.

Finally, the patient's life history must also be taken into account: Apparently the consumption of tobacco and diets rich in fats may favor its appearance. Similarly, a sedentary lifestyle and high levels of stress increase the probability of onset. The presence of certain metabolic diseases such as Diabetes or hypertension are facilitators of Alzheimer's disease.

Treatments

To date, Alzheimer's disease is still incurable, and treatment is based on the prevention and delay of cognitive deterioration.

Pharmacological treatment

At the pharmacological level, different acetylcholinesterase inhibitors tend to be used.an enzyme that degrades brain acetylcholine. In this way, acetylcholine is present in the brain for a longer period of time, prolonging its optimal functioning.

Donepezil is specifically used as a treatment for all stages of Alzheimer's disease, while rivastigmine and galantamine are usually prescribed in the early stages. These drugs have been shown to be able to delay the progression of the disease by about half a year.

Psychological treatment

At the psychological level, occupational therapy and cognitive stimulation are usually used as the main strategies to slow the rate of deterioration. Psychoeducation is also essential in the early stages of the disease, when the patient is still aware of the loss of faculties.

It is not uncommon for individuals who are told they have dementia to suffer from depressive or anxious episodes. Thus, the clinician should evaluate the effect on the subject of reporting the problem.

Work should also be done with the family environment, advising them on the process of deterioration that the patient will follow, his or her loss of autonomy and indicating valid strategies to cope with the situation.

Prevention

Taking into account that the causes of Alzheimer's disease are still unknown and that its treatment is based on slowing down or reducing the symptoms, it is necessary to take into account factors linked to the disorder in order to be able to carry out prevention tasks.

As we have said, a sedentary lifestyle is a risk factor for developing this disease.. Physical exercise has been shown to be an excellent preventive mechanism, since it helps to strengthen both the body and the mind, being useful in a large number of disorders.

Considering that other risk factors include high cholesterol, diabetes and hypertension, dietary control becomes a very important preventive element. It is very useful to have a rich and varied diet with little saturated fats..

Another aspect to be addressed is the level of mental activity. Exercising the brain means strengthening the learning capacity and neuronal connections, so reading or learning new things (not necessarily technical theoretical knowledge) can help to slow down the symptoms or prevent them from appearing.

Finally, one of the fundamental elements of prevention is the early detection of symptoms. Since memory loss is common with age without the involvement of dementia, it is not uncommon for the first signs of Alzheimer's disease to be overlooked. If memory complaints are very frequent and are accompanied by other alterations in behavior and/or other faculties, it would be advisable to visit a medical center where the patient's condition can be evaluated. Attention should also be paid in cases of mild cognitive impairment, which can sometimes progress to various dementias (including Alzheimer's disease).

Bibliographic references:

• American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders. Fifth edition. DSM-V. Masson, Barcelona.

• Förstl, H. & Kurz, A, (1999). Clinical features of Alzheimer's disease. European Archives of Psychiatry and Clinical Neuroscience 249 (6): 288-290.

• Santos, J.L. ; García, L.I. ; Calderón, M.A. ; Sanz, L.J. ; de los Ríos, P. ; Izquierdo, S. ; Román, P. ; Hernangómez, L. ; Navas, E. ; Ladrón, A & Álvarez-Cienfuegos, L. (2012). Psicología Clínica. Manual CEDE de Preparación PIR, 02. CEDE. Madrid.

• Waring, S.C. & Rosenberg, R.N. (2008). Genome-wide association studies in Alzheimer disease. Arch. Neurol. 65 (3): 329-34.