Table 1.

Study groups: inclusion and exclusion criteria

Study groups	Current depression	Suicidal behavior	Suicidal ideation
Late-onset attempters	Yes	First suicide attempt at age 55 or later	Either severe suicidal ideation or suicidal behavior* within the past month
Early-onset attempters	Yes	At least one suicide attempt before the age of 55
Ideators	Yes	No lifetime history of suicidal behavior	Severe suicidal ideation* within the past month
Depressed controls	Yes	No lifetime history of suicidal ideation or behavior	None
Healthy controls	No life-time history of depression

Note: Current depression reflected scores of ≥14 on the HRSD, Hamilton Rating Scale for Depression, as administered at the time of enrollment;

^*Severe suicidal ideation is defined as the desire and plan to make a suicide attempt. Attempters whose suicidal behavior took place earlier than during the last month had to meet current, severe suicidal ideation criteria (all of the attempters were in a current suicidal crisis).