Application of magnetic resonance spectroscopy in geriatric mood disorders

Magnetic resonance imaging of neuroinflammation in chronic pain: a role for astrogliosis?

Noninvasive measures of neuroinflammatory processes in humans could substantially aid diagnosis and therapeutic development for many disorders, including chronic pain. Several proton magnetic resonance spectroscopy (H-MRS) metabolites have been linked with glial activity (ie, choline and myo-inositol) and found to be altered in chronic pain patients, but their role in the neuroinflammatory cascade is not well known. Our multimodal study evaluated resting functional magnetic resonance imaging connectivity and H-MRS metabolite concentration in insula cortex in 43 patients suffering from fibromyalgia, a chronic centralized pain disorder previously demonstrated to include a neuroinflammatory component, and 16 healthy controls. Patients demonstrated elevated choline (but not myo-inositol) in anterior insula (aIns) (P = 0.03), with greater choline levels linked with worse pain interference (r = 0.41, P = 0.01). In addition, reduced resting functional connectivity between aIns and putamen was associated with both pain interference (whole brain analysis, pcorrected < 0.01) and elevated aIns choline (r = -0.37, P = 0.03). In fact, aIns/putamen connectivity statistically mediated the link between aIns choline and pain interference (P < 0.01), highlighting the pathway by which neuroinflammation can impact clinical pain dysfunction. To further elucidate the molecular substrates of the effects observed, we investigated how putative neuroinflammatory H-MRS metabolites are linked with ex vivo tissue inflammatory markers in a nonhuman primate model of neuroinflammation. Results demonstrated that cortical choline levels were correlated with glial fibrillary acidic protein, a known marker for astrogliosis (Spearman r = 0.49, P = 0.03). Choline, a putative neuroinflammatory H-MRS-assessed metabolite elevated in fibromyalgia and associated with pain interference, may be linked with astrogliosis in these patients.

Magnetic resonance imaging in mood disorders: a bibliometric analysis from 1999 to 2020

Objective

Globally, mood disorders are highly prevalent, and are associated with increased morbidity and mortalities. Magnetic resonance imaging is widely used in the study of mood disorders. However, bibliometric analyses of the state of this field are lacking.

Methods

A literature search in the web of science core collection (WoSCC) for the period between 1945 and 2020 returned 3073 results. Data extracted from these publications include, publication year, journal names, countries of origin, institutions, author names and research areas. The bibliometric method, CiteSpace V and key words analysis were used to visualize the collaboration network and identify research trends, respectively.

Results

Since it was first reported in 1999, the use of magnetic resonance imaging in studies on mood disorders has been increasing. Biological psychiatry is the core journal that has extensively published on this topic, while the UNIV PITTSBURGH, USA, has the highest published papers on this topic. Keyword analysis indicated that studies on depression, bipolar disorders, and schizophrenia, with a focus on specific brain regions, including amygdala, prefrontal cortex and anterior cingulate cortex are key research topics.

Conclusion

Brain structure and network, sex differences, and treatment-associated brain changes are key topics of future research.

Application of Magnetic Resonance Diffusion Tensor Imaging in the Clinical Diagnosis of Disc Herniation after Lumbar Spine Injury

Magnetic resonance diffusion-weighted imaging (DTI) provides a unique perspective on the pathophysiological and microstructural changes during spinal cord injury, with high spatial specificity; meanwhile, NM reflects the conduction and integrity of neuroelectrical signals in spinal cord fiber tracts, with time-specific and dynamic evaluation effects. The fractional anisotropy (FA) value, SEP amplitude, and neurological function score or improvement rate are correlated. The combination of DTI and NM can more reliably quantify the spinal cord function, evaluate the effectiveness of treatment, and determine the patient's prognosis, which can provide reference for clinical decision making and future research for SCI patients. That is, the lower the preoperative FA value and the lower the SEP amplitude, the worse the preoperative and postoperative neurological function, the lower the improvement rate, and the worse the prognosis of patients. Therefore, we believe that spinal cord function can be graded according to JOA scores to find the corresponding FA and SEP amplitude ranges and that, by measuring FA and SEP amplitude in the future, we can reverse the assessment of spinal cord function, expected postoperative improvement, and long-term prognosis. At the same time, FA values can also help determine the nature of the lesion to some extent.

Neurotransmitters and Neurometabolites in Late-Life Depression: A Preliminary Magnetic Resonance Spectroscopy Study at 7T

BACKGROUND

Magnetic resonance spectroscopy (MRS) methods have quantified changes in levels of neurotransmitters and neurometabolites in patients with major depression across the lifespan. The application of 7T field strengths and greater have not been a major focus of study in patients with late-life depression (LLD).

METHODS

Nine LLD patients who met DSM-IV criteria for a current major depressive episode and nine non-depressed, healthy, age-matched controls underwent clinical and neuropsychological assessment and single-voxel 7T ¹H-MRS at baseline and after 10-12 weeks of antidepressant treatment (Citalopram; patients only). Spectra were acquired from two brain regions implicated in both depressive symptoms and neuropsychological deficits in LLD, the anterior (ACC) and posterior cingulate (PCC). Levels of γ-aminobutyric acid (GABA), glutamate (Glu), glutathione (GSH), N-acetylaspartylglutamate (NAAG), N-acetylaspartate (NAA), and myo-inositol (mI) were quantified relative to total creatine (tCr) using linear-combination modeling.

RESULTS

Baseline Glu/tCr levels were not significantly different between groups. Decreased Glu/tCr levels after Citalopram treatment were observed in a subset of LLD patients. Exploratory analyses showed that LLD patients had lower NAA levels in the PCC relative to controls. Higher levels of ml in the LLD patients relative to the controls and decreases after Citalopram treatment had large effect sizes but were not statistically significant. Further, decreases in PCC Glu/tCr and increases in ACC GSH/tCr were associated with improvement in depressive symptoms.

LIMITATIONS

Sample size.

CONCLUSIONS

These preliminary results suggest a role of neurochemicals and neurometabolites in the neurobiology of LLD and antidepressant treatment response.

Lamotrigine Therapy and Biomarkers of Cerebral Energy Metabolism in Older Age Bipolar Depression

OBJECTIVE

This study compared brain energy metabolism, as measured by cerebral concentrations of glutamate (Glu), glutamine (Gln), and N-acetyl aspartate (NAA), in older age bipolar depression (OABD) to that of psychiatrically healthy comparison subjects using proton (¹H) magnetic resonance spectroscopy imaging at 4-Tesla. Metabolite levels were assessed in OABD subjects before and after 8 weeks of lamotrigine therapy with the goal of determining relationships between cerebral energy metabolism, depression symptom severity, and changes in depression symptom response.

METHODS

Individuals (n = 21, mean age: 62.0 ± 5.9 years) with bipolar disorder, current episode depressed, and a healthy comparison group (n = 14, mean age: 67.5 ± 8.8 years) were selected. Participants with bipolar disorder, current episode depressed, were treated in open label fashion with lamotrigine monotherapy for 8 weeks. All subjects were scanned with ¹H magnetic resonance spectroscopy at 4T at baseline and again after 8 weeks to assess levels of cerebral metabolites in the anterior cingulate cortex and parieto-occipital cortex. Metabolite levels were examined as ratios relative to creatine (Cr). Response to 8 weeks of lamotrigine treatment in the bipolar disorder, current episode depressed group, was assessed as a continuous measure on the Montgomery-Asberg Depression Rating Scale.

RESULTS

NAA/Cr ratio in OABD was significantly lower by 14% (95% confidence interval: [1%, 26%]) than in comparison subjects at baseline. However, there were no associations between NAA/Cr, Glu/Cr, or Gln/Cr and either depression severity or lamotrigine treatment.

CONCLUSION

Group differences in NAA suggest evidence for a deficit in cerebral energy metabolism in OABD.