O2‐11‐05: HIPPOCAMPAL VOLUME AND THE TEMPORAL COURSE OF DEPRESSIVE SYMPTOMS OVER A SEVEN‐YEAR FOLLOW‐UP: THE SMART‐MEDEA STUDY

Alzheimer's disease and depression often co-occur and both have been associated with hippocampal atrophy. Whether depression precedes or follows hippocampal atrophy is not well known. We examined the temporal course between hippocampal volume at baseline and depressive symptoms measured at 6 month intervals during seven years of follow-up in non-demented persons with a history of vascular disease. Within the SMART-Medea study, an ancillary study to the SMART-MR study on brain changes on MRI among patients with arterial disease, 636 persons (mean age 62±10 years, 81% male) had a 3D T1-weighted 1.5Tesla MRI at baseline on which hippocampal volume were manually segmented and at least one measurement of depressive symptoms. Depressive symptoms were assessed with the Patient Health Questionnair-9 at baseline and biannually during seven years of follow-up. The PHQ-9 assesses presence of the nine DSM-IV symptoms for major depressive disorder in the past 2 weeks. GEE models were used to assess the association between baseline hippocampal volume relative to intracranial volume with depressive symptoms at multiple time points during follow-up. An interaction term between hippocampal volume and time as dummy variable for each time point was included to examine the temporal relatio nship. The overall response on the repeated PHQ-9 assessments varied between 86% and 97%. Median (10 th -90 th percentile) score on the PHQ-9 was 3 (0-8). Mean (SD) total hippocampus volume was 5.96 (0.68) mL. We found a significant interaction between baseline hippocampal volume and time (p-value interaction = 0.044) indicating that the temporal course of depressive symptoms differed over time according baseline to hippocampal volume. Visualizing the temporal course of depressive symptoms showed that patients with relatively small hippocampal volume (lowest quartile) had a more fluctuating course of depressive symptoms compared to patients with relatively large hippocampal volume (upper three quartiles) (Figure 1).