Adherence vs. Adhesion — What's the Difference?

Adherence is primarily about the commitment, loyalty, or attachment to something, such as an idea, policy, or regimen. It involves a psychological or moral component, emphasizing the act of following or holding onto a chosen path. Whereas adhesion focuses on the physical process or phenomenon by which two surfaces become attached to each other. It is often used in scientific and technical contexts to describe how materials bond or stick together.

In the context of health and medicine, adherence describes how well a patient follows a prescribed treatment plan or medication regimen. This concept is crucial for the effectiveness of treatment outcomes and is measured by the extent to which a patient's behavior matches agreed recommendations from a healthcare provider. On the other hand, adhesion in medical terms can refer to abnormal bands of scar tissue that form between internal organs and tissues, often as a result of surgery, causing them to stick together.

Adherence involves an element of choice and active participation, indicating a person's willingness to stick to an agreement, guideline, or set of rules. It is often used in contexts that require sustained commitment or observance. Adhesion, however, is more about the inherent properties of materials or biological tissues that cause them to stick or hold together, without implying any form of decision or volition.

The effectiveness of adherence can be influenced by factors such as personal beliefs, understanding of the benefits, and the perceived importance of the commitment being made. These psychological factors play no role in adhesion, which is determined by physical and chemical properties, such as surface energy, viscosity, and molecular interaction.

While adherence is a concept that can be applied to various fields, including law, religion, and personal behavior, indicating a broader scope of application, adhesion is a term with specific uses in physics, chemistry, and materials science. It describes a critical property that affects the performance and reliability of products, from medical adhesives to building materials.