Alzheimer’s is a degenerative and progressive brain disease that slowly erases the memory and destroys thinking skills, the way of thinking and behavioural patterns. Over time, it can even destroy the ability of carrying out the simplest tasks. For most people affected by this disease, the symptoms appear for the first time after the age of 65.

Alzheimer’s is the most common cause of dementia for older people. Dementia is the loss of cognitive function (that is, the acts of thinking, remembering and reasoning) to such an extent that it interferes with a person’s life and everyday activities.

Alois Alzheimer

The disease was named after Dr. Alois Alzheimer. In 1906 Dr. Alzheimer perceived changes in the brain tissues of a woman who had died from a rare mental disease. Her symptoms included memory loss, language disorders and unpredictable behaviour. After the woman died, Dr. Alzheimer examined her brain and discovered several abnormal masses (currently called amyloid plaques) and twisted fibres (currently called neurofibrillary tangles).

Plaques and tangles in the brain are two of the main characteristics of this disease. The third characteristic would be the loss of connections between the brain and the nerve cells (neurons).


It is difficult to determine a person’s chance of developing Alzheimer’s since we are dealing with a complex alteration of unknown cause in which a wide range of factors are supposed to be involved. Here are some of the elements that can increase the chance of developing this pathology.

  • Age: it tends to affect people over 60-65, but there have also been some cases among people aged 40 and under.  The average age of diagnosis is 80 years old since Alzheimer’s is considered to be a disease advanced by age.
  • Sex: women develop this disease more often, probably because they live longer.
  • Race: it affects all races equally.
  • Genetic heritability: the familial Alzheimer’s, a variation of a pathology that is genetically transmitted, accounts for 1 percent of all cases. Nevertheless, it is estimated that 40 percent of the patients with AD have a family history of the disorder.
  • Genetic factor: it is due to several mutations in the amyloid precursor protein gene (APP) or the presenilin-1 and presenilin-2 gene. This could also be associated with mutations in the apolipoprotein E (ApoE) gene. This protein is involved in the cholesterol transport and elimination. Trends in research indicate that the nicastrin would be responsible for activating production of beta-amyloid.
  • Environmental factors: tobacco as well as high-fat diets have been shown to be a clear risk factor for the pathology. On the other hand, the fact of belonging to a large family is also supposed to affect the risk of developing AD.

Complete neuron cell diagram

Symptoms of Alzheimer’s

Initially, there are small and unnoticeable memory lapses. But over time, this deficiency becomes increasingly apparent and incapacitating for the affected person, who will have trouble performing everyday and simple tasks as well as other intellectual activities such as speaking, understanding, reading or writing. The symptoms vary with the stage of the disease:

  • Mild Alzheimer’s (early-stage): the pain caused by the disease still goes unnoticed for both the patient and the family members. The patient has small memory lapses, such as where he has put the keys or difficulty finding a word. At this stage patients can still work or drive a car, even though they may begin to experience a lack of spontaneity and initiative and depressive symptoms. Their capacity of judgement is reduced and they have difficulty facing new situations or organising activities.  Other symptoms, such as emotional withdrawal, apathy and mood changes may also appear.
  • Moderate Alzheimer’s (middle-stage): the disease is already noticeable for family and friends. The patient has difficulty performing tasks such as shopping, watching TV or planning a dinner.  They are no longer dealing with just memory lapses, but also with reasoning and understanding problems. At this stage, the deterioration progresses quite quickly and those affected can even get lost in familiar places. Also, they are visibly apathetic and depressed.
  • Severe Alzheimer’s disease (late-stage): all areas related to cognitive function are affected. Patients lose their ability to speak properly, and repeat disjointed phrases over and over again. They cannot recognise their family and friends, or even recognise themselves in a mirror. Disorientation is constant. The most critical patients forget how to walk and sit and generally lose control of their bodily functions. They forget about both distant and recent facts, stay still for long periods of time and are not generally able to walk. They cease to be independent individuals and need to be fed or cared for. They shout, cry or laugh for no reason and don’t understand when someone talks to them.  At the most severe level of the stage, articular stiffness and contractures always appear. Moreover, the patients remain silent and may develop deglutition swallowing disorders. Many of them enter a vegetative state.