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Despite novel antidepressant development, 10–30% of patients with major depressive disorder (MDD) have antidepressant treatment-resistant depression (TRD). Although new therapies are needed, lack of knowledge regarding the neural mechanisms underlying TRD hinders development of new therapeutic options. We aimed to identify brain regions in which spontaneous neural activity is not only altered in TRD but also associated with early treatment resistance in MDD. Sixteen patients with TRD, 16 patients with early-phase non-TRD and 26 healthy control (HC) subjects underwent resting-state functional magnetic resonance imaging. To identify brain region differences in spontaneous neural activity between patients with and without TRD, we assessed fractional amplitude of low-frequency fluctuations (fALFF). We also calculated correlations between the percent change in the Hamilton Rating Scale for Depression (HRSD17) scores and fALFF values in brain regions with differing activity for patients with and without TRD. Patients with TRD had increased right-thalamic fALFF values compared with patients without TRD. The percent change in HRSD17 scores negatively correlated with fALFF values in patients with non-TRD. In addition, patients with TRD showed increased fALFF values in the right inferior frontal gyrus (IFG), inferior parietal lobule (IPL) and vermis, compared with patients with non-TRD and HC subjects. Our results show that spontaneous activity in the right thalamus correlates with antidepressant treatment response. We also demonstrate that spontaneous activity in the right IFG, IPL and vermis may be specifically implicated in the neural pathophysiology of TRD.

This study investigated event-related potential (ERP) indices of information-processing in eating disorders. ERPs during an auditory two-tone discrimination task were recorded at midline at 3 sites in 28 anorexic patients, 12 low-weight bulimic patients (body mass index (BMI) under 17.5), 12 normal-weight bulimic patients (BMI over 17.5), and 40 control subjects. The P300 latency was significantly prolonged at all sites in both bulimic groups compared with that in controls, and at frontal and central electrode sites in anorexics. In contrast, the P300 amplitude did not differ between these groups at any site. The prolonged P300 latency in eating disorders suggests a task-related slowing of perceptual decisions that reflects their cognitive impairment.

Aims: Anorexia nervosa (AN) is subdivided into the restricting type (AN-R) and the binge-eating/purging type (AN-BP), but differences in cerebral blood flow between patients with these types of AN and healthy controls have not been investigated. Methods:The present study was designed to elucidate any such differences using resting single photon emission computed tomography (SPECT) studies to compare the differences in cerebral perfusion among both types of AN and a healthy control group. Resting regional cerebral blood flow was assessed using SPECT with technetium-99m hexamethylpropyleneamine oxime in 13 female AN-R patients, 13 female AN-BP patients, and 10 healthy women as controls with 3-D stereotactic surface projections. Results:The analytic program of the SPECT images showed bilateral decreased perfusion of the subcallosal gyrus (SCG), midbrain and posterior cingulate gyrus (PCG) in both AN-R and AN-BP patients, as compared with the controls. There were no clear differences between the AN-R and AN-BP groups. There were no significant differences in cerebral blood flow between patients with AN-R and AN-BP. Conclusions:Abnormalities of the neuronal circuits containing the SCG, midbrain and PCG are possibly relevant to trait-related AN.

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