Many people experience worsening depression symptoms over their final year of life, and a U.S. study suggests that women, younger adults, and poor people may be especially vulnerable.

For the study, researchers examined data on 3,274 adults who participated in the nationwide Health and Retirement Study and died within one year of the assessment. All of the participants had completed mental health questionnaires and provided information on any medical issues they had, as well as demographic factors like income and education levels.

Rates of depressive symptoms increased over the last year of life, particularly within the final months, the study found. By the last month of life, 59% of the participants had enough symptoms to screen positive for a diagnosis of depression, although they were not formally evaluated and diagnosed by clinicians.

“Patients with depression have worse survival outcomes than non-depressed patients, making depression a critical issue to screen for and manage in the context of serious illness,” Elissa Kozlov of the Rutgers University Institute for Health, Health Policy, and Aging Research in New Brunswick, New Jersey, and colleagues write in the Journal of the American Geriatrics Society.

And, “psychological symptoms, such as depression, have a negative impact on patients’ quality of life as they near the end of life,” Kozlov and colleagues write.

Researchers had asked participants whether they experienced eight things over the previous week: depression, sadness, restless sleep, unhappiness, feeling like everything takes effort, lack of motivation, and loneliness. People with at least three symptoms might screen positive for depression, the study team writes.

Across the entire Health and Retirement Study population, including people who didn’t die within a year of their most recent assessments, about 23% of participants have at least three of these symptoms, the researchers also note.

In the current analysis, depression scores remained relatively stable from 12 to four months prior to death, then steadily increased. With four months to live, 42% of participants had at least three symptoms of depression, and with one month remaining, 59% did.

One year before death, women had higher depression symptom scores, with almost three symptoms on average compared to about two for men. With one month to live, both men and women had three or more symptoms and there was no longer a meaningful difference between the sexes.

Differences in depression scores based on age and income were also more pronounced one year before death, and became less pronounced closer to death, the study found.

However, the youngest and poorest participants had the highest depression scores at all points in time. As death approached, nonwhite participants also had increasingly high depression scores.

And, one month before death, people without a high school education had the highest depression scores of all, averaging almost five symptoms.

The study wasn’t designed to prove whether or how terminal illness might impact mental health, or the reverse.

Even so, the results underscore the importance of screening for mental health problems and treating conditions like depression in the final months of life, the researchers conclude.

“Given the range of options to treat depression, unaddressed depressive symptoms in the last year of life must be a focus of both quality measurement and improvement,” the study authors write.

“While depressive symptoms at the end of life are common, they are treatable and must be proactively addressed to reduce distress and ensure that everyone has the opportunity to experience a ‘good death,’ free of depressive symptoms.”