Effects of arterial cannulation stress on regional cerebral blood flow in major depressive disorder

Cerebral blood flow changes and their genetic mechanisms in major depressive disorder: a combined neuroimaging and transcriptome study

BACKGROUND

Extensive research has shown abnormal cerebral blood flow (CBF) in patients with major depressive disorder (MDD) that is a heritable disease. The objective of this study was to investigate the genetic mechanisms of CBF abnormalities in MDD.

METHODS

To achieve a more thorough characterization of CBF changes in MDD, we performed a comprehensive neuroimaging meta-analysis of previous literature as well as examined group CBF differences in an independent sample of 133 MDD patients and 133 controls. In combination with the Allen Human Brain Atlas, transcriptome-neuroimaging spatial association analyses were conducted to identify genes whose expression correlated with CBF changes in MDD, followed by a set of gene functional feature analyses.

RESULTS

We found increased CBF in the reward circuitry and default-mode network and decreased CBF in the visual system in MDD patients. Moreover, these CBF changes were spatially associated with expression of 1532 genes, which were enriched for important molecular functions, biological processes, and cellular components of the cerebral cortex as well as several common mental disorders. Concurrently, these genes were specifically expressed in the brain tissue, in immune cells and neurons, and during nearly all developmental stages. Regarding behavioral relevance, these genes were associated with domains involving emotion and sensation. In addition, these genes could construct a protein-protein interaction network supported by 60 putative hub genes with functional significance.

CONCLUSIONS

Our findings suggest a cerebral perfusion redistribution in MDD, which may be a consequence of complex interactions of a wide range of genes with diverse functional features.

Cerebral metabolism in major depressive disorder: a voxel-based meta-analysis of positron emission tomography studies

BACKGROUND

Major depressive disorder (MDD) is a common mental illness with high lifetime prevalence close to 20%. Positron emission tomography (PET) studies have reported decreased prefrontal, insular and limbic cerebral glucose metabolism in depressed patients compared with healthy controls. However, the literature has not always been consistent. To evaluate current evidence from PET studies, we conducted a voxel-based meta-analysis of cerebral metabolism in MDD.

METHOD

Data were collected from databases including PubMed and Web of Science, with the last report up to April 2013. Voxel-based meta-analyses were performed using the revised activation likelihood estimation (ALE) software.

RESULTS

Ten whole-brain-based FDG-PET studies in MDD were included in the meta-analysis, comprising 188 MDD patients and 169 healthy controls. ALE analyses showed the brain metabolism in bilateral insula, left lentiform nucleus putamen and extra-nuclear, right caudate and cingulate gyrus were significantly decreased. However, the brain activity in right thalamus pulvinar and declive of posterior lobe, left culmen of vermis in anterior lobe were significantly increased in MDD patients.

CONCLUSION

Our meta-analysis demonstrates the specific brain regions where possible dysfunctions are more consistently reported in MDD patients. Altered metabolism in insula, limbic system, basal ganglia, thalamus, and cerebellum and thus these regions are likely to play a key role in the pathophysiology of depression.

Catecholamine depletion in first-degree relatives of individuals with mood disorders: An [(18)F]fluorodeoxyglucose positron emission tomography study

Catecholamine depletion with alpha-methylparatyrosine (AMPT) has previously been shown to induce depressive symptoms in currently remitted patients with major depressive disorder (MDD) but not healthy controls. Thus sensitivity to catecholamine depletion has been hypothesized to be an endophenotype of MDD. Here we tested this hypothesis in the context of a randomized, double-blinded, placebo-controlled design by measuring changes in mood in a group of psychiatrically-healthy individuals at risk of mood disorders by virtue of family history (high-risk subjects, HRs). In addition, we tested whether HRs differed from healthy controls with no family-history of mood disorders (low-risk controls, LRs) in their cerebral metabolic response when undergoing catecholamine depletion. Eight healthy LRs (6 males, mean age = 34.1 ± 7.1) and 6 healthy HRs (3 males, mean age = 29.3 ± 4.6) participated in two, 3-day-long identical sessions during which they completed standardized measures of depression, anxiety and fatigue and an [¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET) scan. On one occasion participants received 4 weight-adjusted doses of AMPT and on the other occasion participants received 4 doses of placebo. The LR and HR groups did not differ from each other in their mood during sham depletion. However, during the period of peak catecholamine depletion, the HR group reported significantly more depression, anxiety and fatigue than the LR group. A region-of-interest analysis showed that during catecholamine depletion versus placebo the combined LR and HR groups displayed a significant increase in cerebral metabolic rate in the left and right ventral striata, left and right amygdalae, and left and right hippocampi (FWE-corrected p < 0.05). Whole brain voxel-wise analyses indicated significantly increased glucose metabolism in the left and right putamina (FWE-corrected p < 0.05) in the combined LR and HR groups in the AMPT versus the placebo session. In the LR group, alone, no significant elevation in glucose metabolism was observed in the regions-of-interest in the catecholamine depletion versus placebo condition. In the HR group, alone, the region-of-interest analysis showed a significant increase in cerebral metabolic rate in the left and right ventral striata (FWE-corrected p < 0.05). No regions-of-interest showed significantly different metabolism in the HR group versus the LR group in the placebo condition, however compared with the LR group, the HR group displayed nominally increased glucose metabolism in the left amygdala during catecholamine depletion (SVC-corrected p = 0.05). A region-of-interest analysis for the interaction contrast confirmed that catecholamine depletion had differential effects on HR and LR participants. Compared with the LR group, the HR group displayed significantly increased glucose metabolism in the left ventral striatum, left amygdala, and left lateral orbitofrontal cortex (OFC) (FWE-corrected p < 0.05). Our results suggest that sensitivity to catecholamine depletion may be a phenotypic marker of vulnerability to mood disorders that is characterized at the neurophysiological level by disinhibition of the striatum and its efferent projections comprising the limbic–cortical–striatal–pallidal–thalamic circuitry.

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High-risk subjects were more depressed and fatigued during catecholamine depletion.

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During depletion HR subjects > metabolism in the left striatum, amygdala, and OFC

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Sensitivity to catecholamine depletion may be an endophenotype of depression.