This quantitative MRI study provides support for a possible association between structural and biochemical substrates and severe drug-resistant major depression.

Distortion of the sense of reality, actualized in delusions and hallucinations, is the key feature of psychosis but the underlying neuronal correlates remain largely unknown. We studied 11 highly functioning subjects with schizophrenia or schizoaffective disorder while they rated the reality of auditory verbal hallucinations (AVH) during functional magnetic resonance imaging (fMRI). The subjective reality of AVH correlated strongly and specifically with the hallucination-related activation strength of the inferior frontal gyri (IFG), including the Broca's language region. Furthermore, how real the hallucination that subjects experienced was depended on the hallucination-related coupling between the IFG, the ventral striatum, the auditory cortex, the right posterior temporal lobe, and the cingulate cortex. Our findings suggest that the subjective reality of AVH is related to motor mechanisms of speech comprehension, with contributions from sensory and salience-detection-related brain regions as well as circuitries related to self-monitoring and the experience of agency.

Heart rate variability (HRV) provides reliable tools to assess the integrity and reactivity of autonomic nervous function. Our aim was to examine HRV in the resting condition and during different mental loads in acute psychosis compared to healthy controls. HRV was measured in 17 first-episode drug-naive patients with psychosis and 21 healthy controls during oddball tasks and while performing the Wisconsin Card Sorting Test. A discrete event series was constructed by an adaptive QRS detector algorithm and power spectrum estimation was carried out. The RMSSD (representing interval differences of successive heartbeats) and the amount of high frequency (HF) power were significantly reduced in patients. Moreover, the patients' HRV remained unaltered during the tasks, whereas in controls the HRV diminished with increasing mental load of the task. Patients with psychosis displayed less short-term HR reactivity than healthy controls. They also failed to adapt HRV according to the task-connected strain. Acute psychosis is characterized by a limited capacity to respond to external demands at the level of autonomic nervous system.

We observed altered purine metabolism in MDD patients compared with non-depressed controls. Furthermore, our observations suggest that circulating xanthine may accumulate in MDD patients.

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Arginine bioavailability may be decreased in MDD. This could impair the production of nitric oxide, and thus add to oxidative stress in the central nervous system.

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