Causes of disease

The causes of disease recognized in Chinese medicine can be divided into the following categories:

Externally contracted causes: Environmental influences including the six excesses and epidemic qì.

• six excesses
• epidemic qì

Internal damage causes: Mental and emotional causes (seven affects), dietary irregularities, and excessive activity or inactivity.

• seven affects
• dietary irregularities
• imbalance of activity and inactivity

Pathological products: Phlegm-rheum; static blood; calculi.

Miscellaneous causes: External injuries (from knocks and falls, cuts, burns and scalds, exposure to chemicals, frostbite, bites, bullet wounds, lifting heavy weights, straining, electric shock); worms; misuse of medicinals (and modern drugs); congenital factors.

• external injuries
• worms
• misuse of medicinals
• congenital factors
• toxins

What are Causes of Disease?

Causes of disease are specific things or events that bring about any morbid condition in an individual. They notably include environmental influences, mental or emotional states, dietary irregularities, and excessive activity or inactivity. In ancient texts, causes of disease were called sources of disease (病源 bìng yuán).

Causes of disease notably include the environmental factors wind, cold, summerheat, dampness, dryness, and fire, which are collectively known as the six excesses. Conventionally, they also include events such as external injuries and excesses of activity or inactivity, as well as products arising from morbid processes, such as phlegm and static blood. By contrast, age, constitutional biases, and previous illness (especially severe, enduring, and recurrent illness) are not normally listed amongst causes, even though these three factors figure prominently in the pathogenesis of vacuity patterns.

In modern literature, the causes of disease are broken down into three or four categories according to various schemes. The classification applied here is widely accepted, but others exist.

Classification of Causes

A traditional classification of causes of disease from the Sān Yīn Jí Yī Bìng Zhèng Fāng Lùn (三因极一病症方论 Unified Treatise on Diseases, Patterns, and Remedies According to the Three Causes) posits three classes of disease causes:

• External causes (外因 wài yīn) of disease are influences from outside the body; they notably include the six excesses.
• Internal causes (内因 nèi yīn) are mental and emotional causes (affect damage).
• Causes neither internal nor external (不内外因 bù nèi wài yīn) include various factors having to do with the individual’s interaction with the environment, such as dietary irregularities, excessive activity or inactivity, and external injuries.

This classification scheme has been replaced in modern textbooks with schemes such as the one outlined above, which includes causes not specifically mentioned in the three causes scheme and which places some causes in different categories. While the three causes limits internal causes to mental and emotional causes, modern schemes include dietary irregularities and imbalances of activity and inactivity among them.

How Causes Affect the body

The various causes of disease produce morbid states of health by damaging the body’s right qì, that is, all the forces including qì, blood, fluids, and essence, and by upsetting the balance of yīn and yáng.

The processes by which this happens are called pathomechanisms (病机 bìng jī). Pathomechanisms are described in terms of specific causes and their effects on different parts or aspects of the body or imbalances of yīn and yáng. Each of the six excesses is known to have specific qualities that affect the body in specific ways. Constitutional biases, excesses of activity or inactivity, severe illness, and the general wear and tear of life are known to cause specific yīn-yáng imbalances and unleash numerous different pathological processes. Thus, for example, among the six excesses, environmental dampness is known to be congealing and stagnating in nature. When it invades the body, it easily clogs the spleen’s movement and transformation function, giving rise to abdominal fullness and sloppy stool. An example of yīn-yáng imbalances is depletion of kidney yīn due to severe illness or the general wear and tear of life. This can deprive the liver of nourishment so that liver yīn fails to counterbalance liver yáng, giving rise to ascendant hyperactivity of liver yáng manifesting in a red complexion and dizziness, a condition often seen in people biomedically diagnosed as having high blood pressure. This in turn can give rise to liver wind, which can give rise to stroke (cerebrovascular accident), which is known as wind stroke in Chinese medicine.