With all the variety of human diseases, they all manifest themselves by changes in three main closely interrelated planes.

The first is structural. It reflects the damage caused by the disease at the level of the structures of the human body. Almost every organ or organ system can be damaged by disease. Damage occurs at the cellular, tissue, organ and systemic levels. Since all organs are closely connected in the process of vital activity, their damage can spread to others, either adjacent anatomically (for example, the spread of a tumor process), or functionally related (damage to the lungs in patients with heart failure), or connected by great vessels (thrombus in the lungs in a patient with blockage of the veins of the lower extremities), or associated with nervous or hormonal regulation. Any disease causes certain changes in the structures of the body, although we cannot determine them in all cases. The possibility of correcting damaged structures (surgery, medications) often determines the outcome and prognosis of the disease.

The second is functional. It reflects the dysfunctions of the body structures resulting from the disease. Functional impairment is often the first manifestation of the disease, and by the nature of this impairment, the damaged structure responsible for this function is determined. There are many diseases, called functional states, when violations mainly relate to the functions of the body, and changes at the level of structures are not detected. Functional recovery in most clinical situations reflects the success of treatment.

The third is personal. It reflects the totality of subconscious and conscious changes that accompany the disease. The personal aspect reflects the entire subjective spectrum of the disease, including the assessment of one’s own feelings, analysis of the course of the disease, its treatment, and those psychological changes that arise as a result of the disease. Pains, dysfunctions that affect every day well-being, constant thoughts about the consequences and the disease itself, change the psychological portrait of a person. Some pathological conditions of the nervous system (depression, apathy, psychosis …) can be a direct consequence of the disease. In cases of psychiatric, neurological and some somatic diseases, personality disorders may appear first, remain basic, and only later be accompanied by functional and structural disorders.

Structural, functional and personal changes are present in all diseases. The only difference is the extent to which they are expressed, and what changes have prevailing clinical significance in each case and at a certain time point.

Structural, functional and personal changes, being in close interconnection, depend on and influence each other according to the principle of direct and feedback connections. They are dynamic on the time axis, and at each point their clinical significance can change. Thus, a disease that began with a structural disorder (myocardial infarction) can lead to a functional problem (heart failure), which in turn can cause a personality reaction (depression), leading to refusal of treatment, and as a result, to the development of repeated myocardial infarction, (structural changes), heart rhythm disturbances (functional), and worsening depression (personality).

The interconnectedness and interdependence of structural, functional and personal changes must be considered when treating a patient. Thus, by optimizing functional disorders, it is possible to reduce structural (normalization of blood pressure in patients with myocardial hypertrophy), leveling the structural problem, improve function (surgery to replace the aortic valve in a patient with heart failure), solving a personal problem, achieve functional and structural improvement (weight loss in a patient with obesity, pulmonary hypertension, and right ventricular failure).

A balanced assessment of the patient’s condition simultaneously in three closely interrelated planes, gives the doctor a more objective vision and understanding of his condition, determines the emphasis in treatment and improves the prognosis.