Understanding Illness: Perceptions, Behaviour and Adherence

1Two patients, one diagnosis

Two men of the same age leave hospital after a mild heart attack, with the same treatment and the same advice. The first believes his heart is now permanently damaged, that the attack was caused by "bad luck and stress" he cannot control, and that he must stop working. The second believes the damage is small, that the attack was linked to smoking and lack of exercise, which he can change, and that he will be back at work in a few weeks.

In a study in New Zealand, Keith Petrie and colleagues (1996) found that such beliefs, measured while patients were still in hospital, predicted who attended cardiac rehabilitation and how quickly patients returned to work, better than the medical severity of the heart attack itself. How people understand their illness shapes how they recover.

21. Leventhal's common-sense model

Howard Leventhal and colleagues (1980) proposed that people act like everyday scientists towards their own symptoms, building a "common-sense" representation of the illness and choosing ways to cope with it (Figure 1).

The model explains why the same disease leads to different behaviour. A person who believes high blood pressure has an "acute" timeline (it comes and goes with stress) may stop taking medicine when he feels calm, although the condition is chronic. Petrie and colleagues (2002) later showed that three short sessions in hospital, which helped heart-attack patients form more accurate perceptions of their illness, led them to return to work sooner than patients who received standard care.

32. Illness behaviour and seeking help

Whether a person seeks help depends on more than symptoms. People are more likely to act when a symptom is visible, severe, frightening or interferes with work, school or relationships. Before going to a health worker, most people consult family and friends, a "lay referral system" (Eliot Freidson), and may try home remedies, a pharmacy or a traditional healer first. Delays can be dangerous: for example, waiting too long with a fever in a malaria area.

43. The sick role

The sociologist Talcott Parsons (1951) argued that society gives a sick person a temporary role with two rights (to be excused from normal duties, and not to be blamed for being ill) and two duties (to want to get well, and to seek and cooperate with competent help). Critics note that the sick role fits short, acute illnesses best. It fits poorly with chronic conditions, which never fully end, and with mental health conditions, whose sufferers are often wrongly blamed or not believed.

54. Adherence to treatment

The WHO's report Adherence to Long-Term Therapies (2003) estimated that, in high-income countries, only about half of patients with long-term conditions take their treatment as recommended, and that rates are often lower where resources are scarce. Reasons include forgetting, side effects, cost, complex instructions, not feeling ill, beliefs that the medicine is unnecessary or harmful, and poor communication with health workers. Philip Ley's cognitive hypothesis model links adherence to patients' understanding of what they are told, their memory of it and their satisfaction with the consultation. Adherence improves with simple regimens, clear explanations checked by asking patients to repeat them, reminders such as text messages, and involving the patient in decisions.

65. Mental illness, stigma and getting help

Mental health conditions such as depression, anxiety and post-traumatic stress are common, real and treatable. Stigma, the belief that they are a weakness, a curse or a person's own fault, stops many people from seeking help and isolates them. Weiner's attribution theory (Unit 2) helps explain this: when people wrongly see an illness as controllable, they blame instead of help. Accurate information, respectful language and contact with people who have recovered reduce stigma.