In contrast to the pathogenesis, which describes the mechanisms of a disease, deals with etiology with the question of "how and why" diseases arise. She asks about the causes and the triggering factors. The word origin goes back to the Greek words "α „τία aitía", cause and "λόγος lógos" reason or doctrine.
What is the etiology?
In medical parlance, this term is often used to describe all the factors that have led to a disease. In this regard, etiology and pathogenesis are brought together. Etiology is a medical specialty that is not exclusively concerned with the healing and therapy of diseases, but is also preventive because it is based on the theory of causes.
Three questions are the pillars of the etiology: Does the identified cause necessarily lead to the outbreak of the disease (causa)? Is the cause the main component of a disease that has already broken out (promoting factors, contributio)? Does the disease occur repeatedly together with the cause without a demonstrable connection (interactions, correlation)?
Processes & goals
This tenet can best be explained with the flu as a disease of the airways and lungs that goes beyond the common cold. The cause of the disease are the flu viruses, because only through them do people get the flu. The viruses are the causa that necessarily lead to the outbreak of the flu (illness). Those who exercise a lot in the fresh air every day have been shown to fall ill less often with the flu because they have a better immune system (contribution, favorable factors).
It has been proven that people who exercise less in the fresh air and are less fit and have a weaker immune system are more likely to get the flu. If the people of the first group fall ill with the flu, which of course cannot be ruled out, the cause (flu viruses) is also involved in the outbreak and course of the disease (cause). There is evidence that people in Greenland are less likely to get the flu. On the basis of this knowledge, the etiology investigates why influenza viruses only spread very rarely in this country (correlation). However, this does not mean that Greenlanders cannot get the flu.
An irrevocable connection between cause and illness has not been proven. Doctors speak of the symbolic three circles that this medical specialty draws around every disease. The inner circle is the cause that describes the cause that leads to the outbreak of an illness. The Contributio as the middle circle describes all behavior and lifestyles that can be the cause of the disease. The correlation as the outer circle examines which interactions can lead to the outbreak of a disease. The important question is where a certain disease occurs more often than elsewhere. The etiology of a tuberculosis disease is the tubercle bacterium.
Researchers have found that people between the ages of 20 and 50 who pursue an intellectually demanding intellectual activity (contribution, promoting factors) are less likely to develop dementia syndromes such as Alzheimer's disease (correlation). The etiology raises the question of whether this demanding activity prevents the disease or whether the predisposition (causa) for the outbreak already exists at a young age and thus prevents the start of an intellectual activity.
The Japanese are the people who have the highest life expectancy. Medical professionals assume that a healthy Asian diet is a decisive factor, but this cannot be proven medically. Another assumption is that island peoples are subject to a lower genetic mix (contributio, favorable factors). However, this assumption is not scientifically proven either.
However, this does not mean that all Japanese automatically get older than average or that all non-Japanese who live in Japan or adopt the healthy Japanese way of life must also reach old age (interactions, correlation). Varices are enlarged, superficial insufficient veins in the subcutaneous adipose tissue. The cause of this undesirable venous phenomenon is a venous congestion (cause), which causes increased venous pressure and, together with the venous weakness, leads to a dilatation of the diseased venous tissue. This chronic venous disease, if left untreated, has serious consequences.
The etiology deals with the question of which favorable factors (contributio) lead to the dysfunction and disease of the affected venous tissue. Favorable factors are a lack of exercise, family history, heavy smoking, high demands such as standing or sitting for long periods, age and pregnancy. Psychology deals with the “multifactorial etiopathogenesis” of depression, personality disorders, schizophrenia, affective disorders as well as mania and bipolar disorder. The appearance and characteristics of these clinical pictures are different, as there is not one cause, but several causally interacting factors that lead to the onset of the disease.
The cause and triggering factors are genetic predisposition, biological and psychosocial factors. Since aetiology is a teaching that searches for the causes of diagnosed diseases and not only wants to treat them, but also to be preventive, it can be applied to all medical fields and when all clinical pictures are present. However, it is primarily a scientific discipline and research area.
Investigation method & subject
The term "illness" is neither medically nor legally defined conclusively. Health is defined in the broadest sense as the “silence of the organs” or as a “state of complete physical, emotional and social wellbeing” (WHO). In the opposite sense, diseases can be understood as disorders of these healthy processes.
According to Virchow, an illness means “living under abnormal conditions with the character of danger”. He understands the disease as a process. Several consecutive, abnormal reactions of an organism or individual components react to a pathogenic irritation. The regulated course of an organism under healthy conditions is no longer given. The diagnosis determines diseases and distinguishes them from one another, it recognizes the internal and external influences that have led to the disease.
These influences are the cause. This is where the etiology comes in, which now deals with the question of how the identified disease could arise and which factors triggered it. The etiology works on the basis of the three "Cs" (Causa, Contributio, Correlatio), each knowing a different degree of causal relationship between disease and cause. It can help doctors and patients to better understand the diagnosed disease and its causes and to classify them rationally.
