Alzheimer’s disease is probably one of the most feared diseases in the general population, due to its high prevalence and the devastating effects that its progression has on those who suffer it. Most people know that this condition causes a progressive deterioration of the mental faculties, of which the most well-known and outstanding (although not the only one) is memory.

Likewise, there is a certain notion that in addition to these losses, Alzheimer’s is increasingly affecting the subject until his or her death. In this sense, it is common for many people to ask themselves what life expectancy an Alzheimer’s patient has . Answering this question is complex, but throughout this article we will try to offer an approximate prognosis based on the average life expectancy of a person with this disease.

What is Alzheimer’s disease?

We know as Alzheimer’s disease one of the most common neurodegenerative diseases, which still has no known cause and is becoming increasingly prevalent, partly due to the progressive aging of the population. This disease, which generates dementia, is characterized by the appearance of a progressive and irreversible deterioration and death of the neurons that populate our brain, something that also generates a progressive loss of cognitive faculties.

This dementia does not appear suddenly, but begins to manifest itself in an insidious manner, first affecting the temporal and parietal cortexes to eventually expand to the rest of the cortex and finally affecting the subcortical structures as well.

On a functional level, the most recognizable symptom in Alzheimer’s is the loss of episodic memory, along with the presence of antegrade amnesia or inability to retain new information.

In addition to this, there are also problems with speech (initially anomie or inability to find the name of things, but over time the difficulties in this sense progress to aphasia), with the recognition/identification of faces and objects, and with motor skills and movement sequencing, something that ends up forming the so-called aphaso-apraxo-agnosic syndrome. Perceptual alterations (such as loss of smell) and behavioural alterations (such as wandering or loss of impulse control which can lead to certain aggression) also appear.

Likewise it is common for delusional ideas of prejudice to appear (some of which may derive from memory problems) and great attentional difficulties, disinhibition or extreme meekness or emotional disturbance.

Three phases

The progression of deterioration typical of this disease occurs over three phases. Initially, in the initial phase, difficulties are seen such as anterograde amnesia , problems with memory and cognitive performance, and in daily life, problems in solving problems and making judgments , a certain withdrawal and possibly depressive symptoms such as apathy, depression or irritability. This first phase usually lasts between two and four years.

Subsequently, a second phase is reached, which can last up to five years, in which the aforementioned aphaso-apraxo-agnostic syndrome begins to appear. This syndrome is characterized, as we have said, by causing more and more problems when communicating, carrying out sequences of movements and being able to identify the stimuli.

There is also spatial-temporal disorientation, loss of recent memory and diminished self-awareness. Apathy and depressive symptoms appear , as well as irritability and it is possible that delirious ideas of harm (partly linked to memory loss) and even verbal or physical aggression may occur. Impulse control is much lower. Problems also appear in daily life activities, something that makes the subject more and more dependent and already requires external supervision for most activities (although he is still capable of performing the most basic ones).

In the third and final phase of this disease, the subject is profoundly impaired. The loss of memory can even affect episodes of childhood , and it can happen that the subject suffers from ecmnesia in which the person believes he is in a moment of childhood. There is already severe difficulty in communication (suffering from severe aphasia in which the ability to understand and express is virtually non-existent) and problems with movement and walking.

It is common that there is also disinhibition of impulses, incontinence, inability to recognize loved ones and even self-recognition in a mirror. Restlessness and anguish are also common, as well as problems with insomnia and lack of response to pain or aversion. The subject usually ends up in bed and with mutism. In this last stage, which ends with death, the subject is totally dependent on the environment in such a way that he needs someone to carry out the basic activities of daily life and even to survive.

Life expectancy in Alzheimer’s patients

We have seen that the process of deterioration that a person with Alzheimer’s suffers is progressive, until it reaches bedtime and eventually death. The period between the onset of symptoms and death can vary greatly from person to person , so talking about a specific life expectancy can be complex. However, the average time that occurs between one and the other, the life expectancy that Alzheimer’s patients usually have, is usually between eight and ten years.

However, it should also be borne in mind that this figure is only an average that should be taken as an approximation: there are cases where death has occurred much earlier or, conversely, people who have lived up to two more decades since the onset of symptoms. Thus, we cannot fully determine how long a person with this disease will survive.

There are many factors that can alter the vital prognosis. One of them is found in the fact that keeping the mind active and keeping the person stimulated contributes to prolong the time in which the person maintains his functions, something that helps to slow down the progress of the disease and improve the quality of life of the person. The lack of physical and mental activity, on the contrary, facilitates its progression. There are also some drugs that in principle help and encourage the functioning of the memory.

In addition to this, it is also relevant to have a social support network that can maintain a supervision of the subject and support him/her (although it is also important that the caregivers also have their own space for themselves), or that they can request the help they need.

Another element that must be taken into account when assessing the effect of Alzheimer’s disease on life expectancy is the age of onset of the disease. It should be taken into account that although when we think of Alzheimer’s the most common thing is to do so in an older person, there are also cases in which it appears early .

Generally, those who suffer from early or presenile forms of Alzheimer’s, that is, who begin to experience symptoms and are diagnosed before age 65, tend to have a worse prognosis and the different phases of the disease tend to follow each other more quickly. Conversely, the later the onset of the disorder, the less effect it has on reducing life expectancy.

Bibliographic references:

  • Förstl, H. & Kurz, A, (1999). Clinical features of Alzheimer’s disease. European Archives of Psychiatry and Clinical Neuroscience 249 (6): 288-290.
  • Petersen R.C. (2007). The current status of mild cognitive impairment–what do we tell our patients? Nat Clin Pract Neurol 3 (2): 60-1.
  • 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.