Lateralized caudate metabolic abnormalities in adolescent major depressive disorder: a proton MR spectroscopy study

Stability of fMRI striatal response to alcohol cues: a hierarchical linear modeling approach

In functional magnetic resonance imaging (fMRI) studies of alcohol-dependent individuals, alcohol cues elicit activation of the ventral and dorsal aspects of the striatum (VS and DS), which are believed to underlie aspects of reward learning critical to the initiation and maintenance of alcohol dependence. Cue-elicited striatal activation may represent a biological substrate through which treatment efficacy may be measured. However, to be useful for this purpose, VS or DS activation must first demonstrate stability across time. Using hierarchical linear modeling (HLM), this study tested the stability of cue-elicited activation in anatomically and functionally defined regions of interest in bilateral VS and DS. Nine non-treatment-seeking alcohol-dependent participants twice completed an alcohol cue reactivity task during two fMRI scans separated by 14 days. HLM analyses demonstrated that, across all participants, alcohol cues elicited significant activation in each of the regions of interest. At the group level, these activations attenuated slightly between scans, but session-wise differences were not significant. Within-participants stability was best in the anatomically defined right VS and DS and in a functionally defined region that encompassed right caudate and putamen (intraclass correlation coefficients of .75, .81, and .76, respectively). Thus, within this small sample, alcohol cue-elicited fMRI activation had good reliability in the right striatum, though a larger sample is necessary to ensure generalizability and further evaluate stability. This study also demonstrates the utility of HLM analytic techniques for serial fMRI studies, in which separating within-participants variance (individual changes in activation) from between-participants factors (time or treatment) is critical.

Review: magnetic resonance spectroscopy studies of pediatric major depressive disorder

Introduction. This paper focuses on the application of Magnetic Resonance Spectroscopy (MRS) to the study of Major Depressive Disorder (MDD) in children and adolescents. Method. A literature search using the National Institutes of Health's PubMed database was conducted to identify indexed peer-reviewed MRS studies in pediatric patients with MDD. Results. The literature search yielded 18 articles reporting original MRS data in pediatric MDD. Neurochemical alterations in Choline, Glutamate, and N-Acetyl Aspartate are associated with pediatric MDD, suggesting pathophysiologic continuity with adult MDD. Conclusions. The MRS literature in pediatric MDD is modest but growing. In studies that are methodologically comparable, the results have been consistent. Because it offers a noninvasive and repeatable measurement of relevant in vivo brain chemistry, MRS has the potential to provide insights into the pathophysiology of MDD as well as the mediators and moderators of treatment response.

Infant brain development and vulnerability to later internalizing difficulties: the Generation R study

OBJECTIVE

Although clinical studies have demonstrated smaller subcortical volumes in structures such as the amygdala, hippocampus, caudate nucleus, and thalamus in adults and adolescents with depressive disorders and anxiety, no study has assessed such structures in babies, long before the development of the disorders. This study examined whether the size of the "gangliothalamic ovoid" (encompassing the basal ganglia and thalamus) assessed during infancy is associated with increased internalizing problems in early childhood.

METHOD

Cranial ultrasounds were used to assess gangliothalamic ovoid diameter and ventricular volume at 6 weeks of postnatal age; moreover, head circumference was measured. Outcome data included ratings of internalizing and externalizing problems using the Child Behavior Checklist (reported by mothers and fathers) at 18 and/or 36 months. Analyses were based on a total of 651 children.

RESULTS

Smaller gangliothalamic diameter was associated with higher Child Behavior Checklist Internalizing scores at ages 18 and 36 months. Results remained significant after correcting for head circumference and were evident for the DSM-oriented subscales of anxiety problems and affective problems. Total ventricular volume was not consistently associated with Internalizing scores.

CONCLUSIONS

Findings associating infant brain measurements with Child Behavior Checklist mother and father reports at two time points are consistent with previous cross-sectional reports of smaller subcortical volumes in depression. Results were not simply reflective of overall brain development, because the pattern held after adjustment for head circumference. This is the first study to point toward a biological vulnerability evident in infancy, involved in the development of internalizing problems in childhood.

Prevalence of incompletely penetrant Huntington's disease alleles among individuals with major depressive disorder

OBJECTIVE

Presymptomatic individuals with the Huntingtin (HTT) CAG expansion mutation that causes Huntington's disease may have higher levels of depressive symptoms than healthy comparison populations. However, the prevalence of HTT CAG repeat expansions among individuals diagnosed with major depressive disorder has not been established.

METHOD

This was a case-control genetic association study of HTT CAG allele size in two discovery cohorts of individuals with major depressive disorder and comparison subjects without major depression as well as a replication cohort of individuals with major depression and comparison subjects without major depression.

RESULTS

CAG repeat lengths of 36 or greater were observed in six of 3,054 chromosomes from individuals with major depression, compared with none of 4,155 chromosomes from comparison subjects. In a third cohort, one expanded allele was observed among 1,202 chromosomes in the major depression group, compared with none of 2,678 chromosomes in comparison subjects. No clear pattern of clinical features was shared among individuals with the expanded repeats.

CONCLUSIONS

In clinical populations of individuals diagnosed with major depression, approximately 3 in 1,000 carried expanded HTT CAG alleles.

Effects of antidepressant treatment on N-acetyl aspartate and choline levels in the hippocampus and thalami of post-stroke depression patients: a study using (1)H magnetic resonance spectroscopy

Previous studies in patients with a major depressive disorder show functional abnormalities in the medial frontal cortex. Functional and structural abnormalities in patients with post-stroke depression (PSD) are not well studied. The major goals of this study were to determine the biochemical abnormalities that occur in PSD and to assess the effect of antidepressants in patients with PSD at the biochemical level. We used magnetic resonance imaging to detect structural or functional abnormalities in PSD patients. In a prospective study, we included 30 patients with PSD and 20 age-matched subjects as controls. Magnetic resonance spectroscopy (MRS) of the brain was conducted in all subjects at the beginning of the study. Patients with PSD were treated with the antidepressant paroxetine (20-40mg/days) for 6 months. After the 6-month period, all PSD subjects underwent MRS again. PSD patients were evaluated with the Hamilton Depression Scale (HAMD) both before and after treatment with the antidepressant. The mean age of the PSD patients was 70.0+/-4.2 years and that of the controls was 67.2+/-5.4 years. Before treatment, N-acetyl aspartate/creatine (NAA/Cr) ratios in the bilateral hippocampus and thalami were significantly lower in PSD patients than in controls. Choline/creatine (Cho/Cr) ratios were significantly higher in the bilateral hippocampus and left thalamus in PSD patients than in controls. The Cho/Cr ratios were significantly higher in the left thalamus than in the right in PSD patients. The HAMD scores were significantly correlated with the Cho/Cr ratios in the left and right hippocampus. Compared with PSD patients before antidepressant treatment, the PSD subjects after treatment had significantly higher NAA/Cr ratios in the left hippocampus and bilateral thalami. They had significantly lower Cho/Cr ratios in bilateral hippocampus and left thalamus. Our study suggests that metabolic abnormalities in the hippocampus and thalamus are implicated in PSD. Antidepressants may alter the local metabolic abnormalities in these areas.

The kynurenine pathway in adolescent depression: preliminary findings from a proton MR spectroscopy study

BACKGROUND

Cytokine induction of the enzyme indoleamine 2,3-dioxygenase (IDO) has been implicated in the development of major depressive disorder (MDD). IDO metabolizes tryptophan (TRP) into kynurenine (KYN), thereby decreasing TRP availability to the brain. KYN is further metabolized into several neurotoxins. The aims of this pilot were to examine possible relationships between plasma TRP, KYN, and 3-hydroxyanthranilic acid (3-HAA, neurotoxic metabolite) and striatal total choline (tCho, cell membrane turnover biomarker) in adolescents with MDD. We hypothesized that MDD adolescents would exhibit: i) positive correlations between KYN and 3-HAA and striatal tCho and a negative correlation between TRP and striatal tCho; and, ii) the anticipated correlations would be more pronounced in the melancholic subtype group.

METHODS

Fourteen adolescents with MDD (seven with melancholic features) and six healthy controls were enrolled. Minimums of 6 weeks MDD duration and a severity score of 40 on the Children's Depression Rating Scale-Revised were required. All were scanned at 3T with MRI, multi-voxel 3-dimensional, high, 0.75 cm(3), spatial resolution proton magnetic resonance spectroscopic imaging. Striatal tCho concentrations were assessed using phantom replacement. Spearman correlation coefficients were Bonferroni-corrected.

RESULTS

Positive correlations were found only in the melancholic group, between KYN and 3-HAA and tCho in the right caudate (r=0.93, p=0.03) and the left putamen (r=0.96, p=.006), respectively.

CONCLUSIONS

These preliminary findings suggest a possible role of the KYN pathway in adolescent melancholic MDD. Larger studies should follow.

Brain volume abnormalities in major depressive disorder: a meta-analysis of magnetic resonance imaging studies

OBJECTIVE

So far, there have been no attempts to integrate the growing number of all brain volumetric magnetic resonance imaging studies in depression. In this comprehensive meta-analysis the magnitude and extent of brain volume differences between 2,418 patients with major depressive disorder and 1,974 healthy individuals from 64 studies was determined.

METHODS

A systematic research was conducted for volumetric magnetic resonance imaging studies of patients with major depressive disorder in relation to healthy control subjects. Studies had to report sufficient data for computation of effect sizes. For each study, the Cohen's d was calculated. All analyses were performed using the random effects model. Additionally, meta-regression analyses were done to explore the effects of potential sources of heterogeneity.

RESULTS

Patients showed large volume reductions in frontal regions, especially in the anterior cingulate and orbitofrontal cortex with smaller reductions in the prefrontal cortex. The hippocampus, the putamen and caudate nucleus showed moderate volume reductions.

CONCLUSIONS

This is the first comprehensive meta-analysis in major depressive disorder demonstrating structural brain abnormalities, particularly in those brain areas that are involved in emotion processing and stress-regulation.

Chronic creatine supplementation alters depression-like behavior in rodents in a sex-dependent manner

Impairments in bioenergetic function, cellular resiliency, and structural plasticity are associated with the pathogenesis of mood disorders. Preliminary evidence suggests that creatine, an ergogenic compound known to promote cell survival and influence the production and usage of energy in the brain, can improve mood in treatment-resistant patients. This study examined the effects of chronic creatine supplementation using the forced swim test (FST), an animal model selectively sensitive to antidepressants with clinical efficacy in human beings. Thirty male (experiment 1) and 36 female (experiment 2) Sprague-Dawley rats were maintained on either chow alone or chow blended with either 2% w/w creatine monohydrate or 4% w/w creatine monohydrate for 5 weeks before the FST. Open field exploration and wire suspension tests were used to rule out general psychostimulant effects. Male rats maintained on 4% creatine displayed increased immobility in the FST as compared with controls with no differences by diet in the open field test, whereas female rats maintained on 4% creatine displayed decreased immobility in the FST and less anxiety in the open field test compared with controls. Open field and wire suspension tests confirmed that creatine supplementation did not produce differences in physical ability or motor function. The present findings suggest that creatine supplementation alters depression-like behavior in the FST in a sex-dependent manner in rodents, with female rats displaying an antidepressant-like response. Although the mechanisms of action are unclear, sex differences in creatine metabolism and the hormonal milieu are likely involved.

Morphology of the corpus callosum in treatment-resistant schizophrenia and major depression

OBJECTIVE

To identify possible differences in the mean midsagittal corpus callosum (CC) total and subdivision areas in treatment-resistant schizophrenia and depression (TRS and TRD) patients.

METHOD

Areas of the total CC and its five equidistant subregions (from CC1 to CC5) obtained by parallel grid partitioning schemes were manually segmented from brain MRI of 42 TRS, 45 TRD patients and 30 healthy controls. The intracranial volume (ICV) normalized areas were calculated and compared between groups.

RESULTS

When compared with controls, patients with TRS had reduced ICV and a larger CC5, and TRD patients had a smaller CC4 while no significant difference in CC total area in patients with TRS or TRD was found. Multiple individual segments and total CC areas were significantly larger in TRS than TRD patients after normalization.

CONCLUSION

Patients with TRS and TRD have different CC morphological characteristics, and therefore there may be aberrant interhemispheric connectivity in schizophrenia and major depressive disorder patients.

Childhood adversity is associated with left basal ganglia dysfunction during reward anticipation in adulthood

BACKGROUND

Childhood adversity increases the risk of psychopathology, but the neurobiological mechanisms underlying this vulnerability are not well-understood. In animal models, early adversity is associated with dysfunction in basal ganglia regions involved in reward processing, but this relationship has not been established in humans.

METHODS

Functional magnetic resonance imaging was used to examine basal ganglia responses to: 1) cues signaling possible monetary rewards and losses; and 2) delivery of monetary gains and penalties, in 13 young adults who experienced maltreatment before age 14 years and 31 nonmaltreated control subjects.

RESULTS

Relative to control subjects, individuals exposed to childhood adversity reported elevated symptoms of anhedonia and depression, rated reward cues less positively, and displayed a weaker response to reward cues in the left globus pallidus. There were no group differences in right hemisphere basal ganglia response to reward cues or in basal ganglia response to loss cues, no-incentive cues, gains, or penalties.

CONCLUSIONS

Results indicate that childhood adversity in humans is associated with blunted subjective responses to reward-predicting cues as well as dysfunction in left basal ganglia regions implicated in reward-related learning and motivation. This dysfunction might serve as a diathesis that contributes to the multiple negative outcomes and psychopathologies associated with childhood adversity. The findings suggest that interventions that target motivation and goal-directed action might be useful for reducing the negative consequences of childhood adversity.

Reduced activation in lateral prefrontal cortex and anterior cingulate during attention and cognitive control functions in medication-naïve adolescents with depression compared to controls

BACKGROUND

There is increasing recognition of major depressive disorder (MDD) in adolescence. In adult MDD, abnormalities of fronto-striatal and fronto-cingulate circuitries mediating cognitive control functions have been implicated in the pathogenesis and been related to problems with controlling negative thoughts. No neuroimaging studies of cognitive control functions, however, exist in paediatric depression. This study investigated whether medication-naïve adolescents with MDD show abnormal brain activation of fronto-striatal and fronto-cingulate networks when performing tasks of attentional and cognitive control.

METHODS

Event-related functional magnetic resonance imaging was used to compare brain activation between 21 medication-naïve adolescents with a first-episode of MDD aged 14-17 years and 21 healthy adolescents, matched for handedness, age, sex, demographics and IQ. Activation paradigms were tasks of selective attention (Simon task), attentional switching (Switch task), and motor response inhibition and error detection (Stop task).

RESULTS

In all three tasks, adolescents with depression compared to healthy controls demonstrated reduced activation in task-relevant right dorsolateral (DLPFC), inferior prefrontal cortex (IFC) and anterior cingulate gyrus (ACG). Additional areas of relatively reduced activation were in the parietal lobes during the Stop and Switch tasks, putamen, insula and temporal lobes during the Switch task and precuneus during the Simon task.

CONCLUSIONS

This study shows first evidence that medication-naïve adolescents with MDD are characterised by abnormal function in ACG and right lateral prefrontal cortex during tasks of attention and performance monitoring, suggesting an early pathogenesis of these functional abnormalities attributed to MDD.

A review of imaging techniques for systems biology

This paper presents a review of imaging techniques and of their utility in system biology. During the last decade systems biology has matured into a distinct field and imaging has been increasingly used to enable the interplay of experimental and theoretical biology. In this review, we describe and compare the roles of microscopy, ultrasound, CT (Computed Tomography), MRI (Magnetic Resonance Imaging), PET (Positron Emission Tomography), and molecular probes such as quantum dots and nanoshells in systems biology. As a unified application area among these different imaging techniques, examples in cancer targeting are highlighted.