The term ‘adjustment’ refers to the process of adjusting to new and difficult circumstances.

As stated above, it is natural to feel frightened or worried when given bad news, especially if this concerns a life‐threatening illness. Adjusting to new and difficult circumstances is a process, rather than a one‐off event, and is likely to take time.

One useful model of adjustment is Brennan's ([36]) Social Cognitive Transition Model. In keeping with ideas from attachment theory, Brennan's model postulates that people hold mental models of the world that influence their assumptions and expectations. When a person's lived experience confirms their expectations and assumptions, their worldview is strengthened. However, when a person's experience disconfirms their worldview, they enter a process of adjustment, whereby new information is assimilated into their working models.

Brennan ([36]) posits that there are a number of reasons for the range of psychosocial responses to difficult experiences such as illness:

During this time, the patient is likely to experience some distress as they comprehend the magnitude of their diagnosis or health experience. They may engage (often unconsciously) in emotional regulation strategies such as denial (discussed later in this chapter) or avoidance (behaviour through which a person attempts to escape an unpleasant thought, feeling, sensation or situation). All of these responses may be helpful in the short term but are potentially unhelpful in the longer term as they can block adjustment. Conversely, people may engage in helpful coping strategies, such as problem solving or engaging with appropriate social support.

Adjustment to difficulties can lead to personal development. As people reflect on their lives and the world around them, they can clarify what is important to them, set goals across different domains in their life (e.g. relationships, work or education, leisure and health) and shape their behaviour accordingly.

Adjustment is also a process that takes place in the family of the patient, and how much time it takes varies from family to family. There are a number of factors that can influence the process of family adjustment, including attachment styles within the family, family scripts (the ‘story’ a family shares that determines how they relate to each other and cope with life, e.g. during illness or celebrations), members’ roles and relationships to help, as well as the family's stage within the family life cycle. For example, a young father may fear death all the more because he is aware that his spouse will lose not only a romantic partner but also a co‐parent. His children will lose an important source of many kinds of support and guidance. A child may struggle to accept that their father is seriously ill because the loss of a parent is the loss of a significant attachment figure, but it could also change the family structure beyond recognition, if that parent is the sole source of income.

The dilemmas and tensions regarding independence and responsibility that frequently arise between parents and adolescents may be magnified if one or the other develops a serious illness. A child may become a ‘young carer’, taking on adult responsibilities for their sick parent, or a parent may become overly fearful of letting their child leave home for university.

Circumstances within family members’ wider systems also affect adjustment. The cumulative effects of trying to cope with the pressure of school exams while worrying about an ill brother may be beyond the internal resources of a sibling. In the same vein, a supportive work environment can foster resilience by reducing work‐related stress.