Long-term fluctuations in depressive symptoms are not associated with other markers of brain health in midlife, according to new research published in the Journal of Psychiatric Research. The findings suggest that the link between depressive symptom trajectories and brain health may only emerge in later life.
‘As psychiatric epidemiologists, our goal is to advance understanding of the development, determinants and consequences of psychiatric phenotypes such as depressive symptoms,’ said study authors Annemarie Luik and Isabel Schuurmans of Erasmus MC University Medical Center Rotterdam.
“Through this study, we wanted to untangle how depressive symptoms develop over time and how these symptom trajectories are associated with subsequent brain health. This information may in turn inform the development of interventions and treatments to promote brain health in people with depression.
For their study, the researchers analyzed data from 1,676 participants in the Origins of Alzheimer’s Disease Across the Life Course (ORACLE) study, which conducted follow-up assessments of previously pregnant women and their partners who had a due date. between April 2002 and January 2006 .
Mothers and their partners completed assessments of depressive symptoms in mid-pregnancy, three years postpartum, ten years postpartum, and during the brain scan session. The neuroimaging scans were taken 15 years postpartum, when the participants were on average about 47 years old.
“In this study, we identified weak or no associations between depressive symptom trajectories and brain health in midlife,” the researchers told PsyPost. They analyzed markers of brain health such as gray and white matter volume, white matter lesions, brain microbleeds, and subcortical structures.
“This finding contrasted with a study focusing on later life, which found associations between depression symptom trajectories and brain health. Thus, the conclusion here would be that changes in depression symptoms may not have a major impact on brain health in midlife, but that this relationship may only become important later in life.
Luik and Schuurmans also highlighted a particularly surprising finding.
“We found that participants with low but increasing depressive symptoms over time had more cortical thickening in a small brain region in the lateral occipital cortex,” they explained. “This finding was unexpected, as in contrast to the previous literature on depression, we found more rather than less cortical thickness.”
“Furthermore, the region was involved in responding to visual form information and processing objects, which is not a typical hallmark of depression. Together, this could imply that visual processing is increased in those with more depressive symptoms, but more research should be done to ensure this finding was not a chance finding.
The study, like all research, comes with some caveats.
“The first measurement of depressive symptoms occurred when our participants were expecting a baby. While pregnancy in general is considered a positive life event, women also experience decreased physical health and more depressive symptoms during this time,” Luik and Schuurmans said.
“It is therefore possible that the measurement of depressive symptoms during this period was more severe due to the pregnancy. More research is needed to understand whether depressive symptoms during pregnancy have a different effect on brain health than depressive symptoms at other times in life.
The study, “10-year trajectories of depressive symptoms and subsequent brain health in middle-aged adults,” was written by Isabel K. Schuurmans, Sander Lamballais, Runyu Zou, Ryan L. Muetzel, Manon HJ Hillegers, Charlotte AM Cecil and Annemarie I. Luik.