Much of the challenge in assessing depression lies in deciding when the boundaries dividing normal depressed mood, dysthymia, and ajor depression are crossed. Very much the same issue occurs with dementia, in which the boundaries between normal cognitive declines of aging, impaired cognition, and full dementia are matters of continuing debate. In the case of depression, the occurrence of features such as delusions, marked loss of weight, and suicidal threats are commonly taken as boundary markers for major depression; several sets of criteria have been proposed (10). The criteria in the fourth edition of the DSM (DSM-IV) take change in affect as the central feature, accompanied by a depressed mood for most of the day, or a markedly diminished interest in daily activities. Frequency and duration are also considered: these symptoms should have occurred nearly every day for at least two consecutive weeks. Inaddition, four or more further symptoms must be present to qualify for major depression; the DSM-IV provides detailed definitions. These further symptoms include significant change in weight, insomnia or hypersomnia, psychomotor agitation or retardation, fatigue, feelings of worthlessness or guilt, diminished ability to concentrate, and suicidal ideation (8, p327). Severe depression is present when the person shows nearly all the symptoms of depression, and it keeps her or him from participating in regular activities; moderate depression is present when the person has many of the symptoms and the depression often keeps her or him from doing the things he needs to do. Mild depression implies that a person shows some of the symptoms of depression, and doing regular activities takes extra effort.