Long-term fluctuations in depressive symptoms are not associated with other brain health markers in middle age, 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 late-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.
“By means of this study, we wanted to disentangle 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 individuals with depression.”
For their study, the researchers analyzed data from 1,676 participants from the Origins of Alzheimer’s Disease Across the Life Course (ORACLE) Study, which conducted follow-up assessments on previously pregnant women and their partners who had a delivery date between April 2002 and January 2006.
The mothers and their partners completed assessments of depressive symptoms mid-pregnancy, three years after childbirth, ten years after childbirth, and during the brain scan session. The neuroimaging scans were performed 15 years after childbirth, when the participants were roughly 47 years old on average.
“In this study, we identified weak to no associations between trajectories of depressive symptoms and brain health in midlife,” the researchers told PsyPost. They analyzed brain health markers such as gray and white matter volume, white matter lesions, cerebral microbleeds, and subcortical structures.
“This finding contrasted a study that focused on late life instead, which found associations between depression symptoms trajectories and brain health. Therefore, the take- away here would be that changes in depression symptoms may not have a major impact on brain health at middle age, but that this relationship may become prominent only later in life.”
Luik and Schuurmans also highlighted a finding that was particularly surprising.
“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 with earlier depression literature, we found more rather than less cortical thickness.”
“In addition, the region was involved in the response to visual shape information and the processing of 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 conducted to ensure that this finding was not a chance finding.”
The study, like all research, includes some caveats.
“The first depressive symptoms measurement took place when our participants were expecting a child. Although pregnancy in general is considered a positive life event, women also experience decreased physical health and more depressive symptoms during this period,” Luik and Schuurmans said.
“It is therefore possible that the depressive symptoms measurement during this period was more severe because of the pregnancy. More research is needed to understand if 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 authored by Isabel K. Schuurmans, Sander Lamballais, Runyu Zou, Ryan L. Muetzel, Manon H.J. Hillegers, Charlotte A.M. Cecil, and Annemarie I. Luik.