Beta-amyloid deposition in patients with major depressive disorder with differing levels of treatment resistance: a pilot study

Background: Lack of treatment response in patients with late-life depression is common. The role of brain beta-amyloid (A beta) deposition in treatment outcome in subjects with late-life depression remains unclear. The present study aimed to investigate brain A beta deposition in patients with major depressive disorder (MDD) with differing treatment outcomes in vivo using F-18-florbetapir imaging. This study included 62 MDD patients and 18 healthy control subjects (HCs). We first employed the Maudsley staging method (MSM) to categorize MDD patients into two groups according to treatment response: mild treatment resistance (n = 29) and moderate-to-severe treatment resistance (n = 33). The standard uptake value ratio (SUVR) of each volume of interest was analysed, and voxel-wise comparisons were made between the MDD patients and HCs. Vascular risk factors, serum homocysteine level, and apolipoprotein E (ApoE) genotype were also determined. Results: The MDD patients with moderate-to-severe treatment resistance had higher 18F-florbetapir SUVRs than the HCs in the parietal region (P < 0.01). Voxel-wise comparisons further demonstrated elevated SUVRs in MDD patients with moderate-to-severe treatment resistance in the precuneus, parietal, temporal, and occipital regions. The MDD patients with mild treatment resistance were found to have increased F-18-florbetapir uptake mainly in the left frontal and parietal regions as compared with the HCs. In addition, voxel-to-voxel correlation analysis showed that brain A beta deposition was correlated positively with MSM score in the occipital region. F-18-florbetapir SUVRs were correlated negatively with Mini Mental Status Examination (MMSE) score in the sample of all MDD patients (r = -0.355, P = 0.005). Conclusions: This study provided preliminary evidence that region-specific A beta deposition was present in some (but not all) MDD patients, especially in those with moderate-to-severe treatment resistance, and their depressive symptoms may represent prodromal manifestations of Alzheimer's disease (AD). Depressive symptomatology in old age, particularly in subjects with a poor treatment response, may underscore early changes of AD-related pathophysiology.