Cancer, HIV/AIDS and dementias are some of the disorders of greatest concern to the Western population today, with some of the most common disorders still not having an effective solution or treatment.

Within the group of dementias, the best known is the dementia produced by Alzheimer’s disease .

Alzheimer’s: general definition

Alzheimer’s disease is one of the most common and well-known neurodegenerative diseases. It is a chronic and currently irreversible disorder with unknown causes that acts by producing a progressive deterioration in the mental faculties of those who suffer from it . Initially it acts only at the cortex level, but as the deterioration progresses it ends up affecting the subcortical level as well. From an insidious beginning, the first lesions appear in the temporal lobe and later expand to other lobes such as the parietal and frontal lobes.

Currently its diagnosis is only considered totally definitive after the death of the patient and the analysis of his tissues (before death its 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 , with an average duration of between eight and ten years.

Typical symptoms

  • For a more in-depth look at the symptoms: “The First 11 Symptoms of Alzheimer’s (and their explanation)”

One of the most characteristic and well-known symptoms is the loss of memory, which usually occurs gradually . The first thing that is lost is recent memory, so that as the disease continues its course it forgets aspects and elements that are increasingly distant in time. It also diminishes the capacity for attention, judgment and the ability to learn new things.

Like most cortical dementias, Alzheimer’s disease is characterized by a progressive loss of function that occurs especially in three areas, forming what has been called the aphaso-apraxo-agnostic syndrome. In other words, throughout its deterioration, the patient loses the ability to speak (the presence of anomie or difficulty in remembering the name of things is very typical), perform sequential actions or even recognize the stimuli coming from the outside, culminating in a state of mutism and immobility. The presence of falls, alterations in sleeping and eating, emotional and personality alterations and loss of smell are also common in those suffering from Alzheimer’s.

Over time, the subject tends to become disoriented and lost, to have strange and careless behaviors, to forget the value of things, and even ends up being unable to recognize his or her loved ones. As the disease progresses, the subject gradually loses his or her 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, with prevalence increasing with age. It is considered early-onset or presenile if it begins before 65, and senile or late-onset if it occurs after that age. The younger the age of onset, the worse the prognosis, with symptoms advancing more rapidly.

Deterioration process: stages of the disease

As we have said, Alzheimer’s disease causes a progressive deterioration of the patient’s mental functions. This progressiveness can be observed throughout the three phases in which the degeneration process has been differentiated.

In addition to these phases, it must be taken into account that sometimes there may be a period of time prior to the onset of the disorder when the individual suffers a mild cognitive impairment (usually of an amnesiac type).

Phase one: Initiation of problems

In the early stages of the disease, the patient begins to experience small memory deficits. It is difficult for them to remember what they have just done or eaten, and to retain new information (in other words, they suffer from anterograde amnesia). Another especially typical symptom is anomia, or difficulty in remembering the names of things despite knowing what they are.

Judgment and problem solving skills are also compromised , performing less in work and daily activities. Initially, the patient is aware of the appearance of limitations, being frequent the appearance of depressive and anxious symptoms such as apathy, irritability and social withdrawal. This first phase of Alzheimer’s disease can last up to four years.

Second phase: Progressive loss of capacity

The second phase of Alzheimer’s disease is characterised by the appearance of the aphaso-apraxo-agnosic syndrome , together with the appearance of retrograde amnesia. That is, the subject begins to have problems in understanding and emitting language beyond the anomie, as well as having severe difficulties in performing sequenced activities and recognizing objects, people and stimuli, in addition to beginning to have problems in remembering past events (until now, memory loss has mainly been related to events that had just occurred and were not retained).

The patient needs supervision and is not able to perform instrumental activities, but may be able to perform basic activities such as dressing or eating on his own. There is usually temporospatial disorientation, and it is not uncommon for it to be lost.

Phase Three: The Advanced Stage of Alzheimer’s Disease

During the third and final phase of the disease, the deterioration of the individual is particularly intense and evident. Episodic memory loss can be as far back as childhood. There is also semantic memory loss. The subject ceases to recognize his relatives and loved ones and is even unable to recognize himself in an image or a mirror.

They tend to have extremely severe aphasia that can result in total mutism, as well as uncoordination and gait disturbances. There is a total or almost total loss of autonomy, depending on external caregivers to survive and not being able to by themselves and they lose the basic skills of daily life, having total dependence on external caregivers. It is frequent that episodes of restlessness and personality alterations appear.

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

Neuropsychological characteristics

The dementia produced by Alzheimer’s disease causes a series of effects in the brain that end up provoking the symptoms.

In this sense , the progressive reduction of the level of acetylcholine in the brain stands out, 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 progressive degradation of brain structures.

In Alzheimer’s disease, structural degradation begins in the temporal and parietal lobes, and then progresses along the course of the disorder to the front and gradually to the rest of the brain. Over time, neuronal density and mass are reduced, and the ventricles dilate to occupy the space left by the 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 on this type of dementia has tried to explain how and why Alzheimer’s disease arises . However, there is still no evidence of why it appears.

At the genetic level, mutations are suspected in the APP gene, the amyloid precursor protein, as well as in the ApoE gene, which is linked to the production of cholesterol-regulating proteins.

The decrease in the level of cerebral acetylcholine causes the degradation of the various structures, and the 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 number of risk factors that must be taken into account when carrying out prevention tasks.

One of the factors to take 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 mental activity of the individual also plays a role. The greater the mental exercise, the greater the resistance and strength of the neuronal connections. However, this effect, although positive since it slows down the progression of the disease, can make it difficult to identify the problem and its treatment.

Another is family history . Although Alzheimer’s disease is not usually genetically transmitted (except for a 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: It seems that the consumption of tobacco and high-fat diets can encourage their appearance. Similarly, a sedentary life with high levels of stress increases the likelihood of occurrence. The presence of some metabolic diseases such as diabetes or hypertension are facilitating elements of Alzheimer’s disease.


To date, Alzheimer’s disease remains incurable, with treatment based on prevention and delay of cognitive decline.

Pharmacological treatment

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

Specifically, donepezil is used as a treatment for all phases of Alzheimer’s disease, while rivastigmine and galantamine are often 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

On a psychological level, occupational therapy and cognitive stimulation are often used as the main strategies to slow down the rate of deterioration. Likewise, psychoeducation is fundamental in the first stages of the disease, when the patient is still aware of the loss of faculties.

It is not uncommon for individuals indicated as having dementia to suffer from depressive or anxiety-type episodes. Thus, the clinician should evaluate the effect on the subject of reporting the problem.

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


Considering 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 preventive tasks.

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

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

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

Finally, one of the key elements of prevention is the early detection of symptoms. Since memory loss without the involvement of dementia is common with age, it is not uncommon for the first signs of Alzheimer’s disease to be ignored. If memory complaints are very frequent and are accompanied by other behavioural and/or faculty alterations, it would be advisable to go to a medical centre where the patient’s condition could be assessed. Attention should also be paid to cases of mild cognitive impairment, which can sometimes progress to different dementias (including that resulting from 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 and Álvarez-Cienfuegos, L. (2012). Clinical Psychology. Manual CEDE de Preparación PIR, 02. CEDE. Madrid.
  • Waring, S.C. & Rosenberg, R.N. (2008). Genome-wide association studies in Alzheimer’s disease. Arch. Neurology. 65 (3): 329-34.