The laws that bestow this right are based upon the principle of maximising autonomy, which asserts that competent adults should be allowed to make their own choices about their own lives, provided these choices do not cause harm to others. This principle assumes that the choices are not influenced by mental illness. However, one would expect that a patient with major depression might be more likely to refuse life-sustaining treatment, because of the cognitive effects of the depression. They asked a cohort of elderly, depressed people to imagine which life-sustaining treatments they would reject in two hypothetical situations. They found that, on average, people rejected more life-sustaining treatments when they were depressed than when they had later recovered.
Major depression is eminently treatable.
If it can influence the seriously ill to refuse treatment, then some of those who do refuse treatment might be depressed and might change their minds if the depression were treated. Other recent studies have also shown a link between depression and a desire to die. 5 Emanuel et al. found that oncology patients who seriously considered and prepared for euthanasia or physician-assisted suicide were significantly more likely to be depressed. 6 Taken together, these studies underline the importance of recognising and treating major depression before meeting a request to withdraw life-sustaining treatment. Unfortunately, the diagnosis of major depression in the gravely ill is very difficult.