31P RINEPT MRSI and VBM reveal alterations in brain aging associated with major depression.

PURPOSE: Phosphomono- and diesters, the major components of the choline peak in (1) H magnetic resonance spectroscopy, are associated with membrane anabolic and catabolic mechanisms. With the refocused insensitive nuclei-enhanced polarization transfer technique, these phospholipids are edited and enhanced in the (31) P MR spectrum. In depressed patients, alterations of the choline peak and cerebral volume have been found, indicating a possible relation. Thus, combining MR phosphorous spectroscopy and volumetry in depressed patients seems to be a promising approach to detect underlying pathomechanisms. METHODS: Depressed in-patients were either treated with antidepressive medication or with electroconvulsive therapy and compared to matched healthy controls. (31) P magnetic resonance spectroscopy imaging was conducted before and after the treatment phases. A 3D MRI dataset for volumetry was acquired in a dedicated (1) H head coil. RESULTS: Phosphocholine and phosphoethanolamine were increased in depressed patients. Though patients responded to the treatments, phospholipids were not significantly altered. An increased age-related gray matter loss in fronto-limbic regions along with an altered relation of phosphomonoesters/phosphodiesters with age were found in depressed patients. DISCUSSION: The findings of increased phosphomonoesthers and an age*group interaction for gray matter volumes need further research to define the role of phospholipids in major depression and possible associations to gray matter loss.

Loss of control of alcohol use and severity of alcohol dependence in non-treatment-seeking heavy drinkers are related to lower glutamate in frontal white matter.

BACKGROUND: The development and maintenance of alcohol use disorders (AUD) have been hypothesized to be associated with an imbalance of glutamate (GLU) homeostasis. White matter (WM) loss, especially in anterior brain regions, has been reported in alcohol dependence, which may involve disturbances in both myelin and axonal integrity. Frontal lobe dysfunction plays an important role in addiction, because it is suggested to be associated with the loss of control over substance use. This study investigated magnetic resonance spectroscopy (MRS)-detectable Glu levels in frontal WM of non-treatment-seeking heavy drinkers and its associations with AUD symptoms. METHODS: Single-voxel MR spectra optimized for Glu assessment (TE 80 ms) were acquired at 3T from a frontal WM voxel in a group of heavy drinking, non-treatment-seeking subjects in comparison with a group of subjects with only light alcohol consumption. RESULTS: The results corroborate previous findings of increased total choline in heavy drinking subjects. A negative association of Glu levels with severity of alcohol dependence and especially loss of control over time and amount of alcohol intake was observed. CONCLUSIONS: In contrast to the rather unspecific rise in choline-containing compounds, low Glu in frontal WM may be specific for the shift from nondependent heavy drinking to dependence and does not reflect a simple effect of the amount of alcohol consumption alone.

Experience of social discrimination correlates with neurometabolism: a pilot study in heroin addicts.

Experimental social neuroscience has shown that being socially excluded is processed in the anterior cingulate cortex (ACC). We hypothesize that a chronic form of social exclusion resembling one aspect of social stigmatization is associated with altered neural plasticity reflected by neurometabolic alterations in the ACC. To test this hypothesis, a highly stigmatized patient group of heroin addicts (N = 15) during opiate maintenance therapy rated a questionnaire about being stigmatized, and neurometabolic markers in the ACC were determined using (1)H MR spectroscopy. We found a negative correlation between discrimination experience and N-acetylaspartate (NAA), indicating attenuated neuron functioning in the anterior cingulate cortex in those patients reporting high discrimination experience. Furthermore, perceived stigmatization showed an association with anxiety that was mediated by NAA. Although the correlative analysis cannot give evidence for a causal relationship, the relation of NAA in the ACC and discrimination experience indicates a malfunction of the neural system involved in cognitive control over emotionally relevant social stimuli in discrimination reporting heroin addicts. Further research is needed to elucidate factors associated with chronic stigmatization.

MR spectroscopy in opiate maintenance therapy: association of glutamate with the number of previous withdrawals in the anterior cingulate cortex.

Pre-clinical research indicates that opioids reduce extracellular glutamate in acute opioid treatment, whereas during withdrawal, glutamatergic neurotransmission is increased and withdrawal symptoms can be blocked by glutamate receptor antagonists. The glutamate hypothesis of addiction suggests that withdrawal-associated hyperglutamatergic states destabilize the glutamatergic system chronically and contribute to relapse. magnetic resonance spectroscopy at three tesla optimized for glutamate assessment (TE 80 ms) was performed in the anterior cingulate gyrus (ACC) and frontal white matter (fWM) of 17 opiate-dependent patients during opiate maintenance therapy and 20 healthy controls. Controlling for age and gray matter content, glutamate in the ACC was positively associated with the number of previous withdrawals. For glutamate + glutamine (Glx), a significant group-age interaction was found. Whereas Glx declines with age in healthy controls, Glx increases with age in opiate-dependent patients. The number of previous withdrawals did not correlate with age. In fWM spectra, increased Cho concentrations were observed in opiate-dependent patients. Both new findings, the positive correlation of glutamate and previous withdrawals and increasing Glx with age in contrast to an age-dependent Glx decrease in controls indicate a destabilization of the glutamate system in opiate-dependent patients and support the glutamate hypothesis of addiction. Increased Cho concentrations in fWM corroborate findings of WM abnormalities in opioid-dependent subjects.

MR spectroscopic evaluation of N-acetylaspartate's T2 relaxation time and concentration corroborates white matter abnormalities in schizophrenia.

Magnetic resonance spectroscopy enables the in vivo analysis of certain aspects of brain biochemistry. Reduced N-acetylaspartate in key regions of schizophrenia has been reported repeatedly but not without controversy. Our objective is to investigate whether reduced N-acetylaspartate concentrations determined without correction for individual T2 relaxation time (referred to as 'apparent tNAA concentration') are due to a reduced absolute N-acetylaspartate concentration or to altered relaxation properties. For this purpose we measured absolute concentrations while evaluating individual T2 relaxation times. We evaluated the metabolite concentrations and metabolite/water relaxation times of a frontal white matter voxel from 23 patients who met DSM-IV criteria for schizophrenia and 29 healthy control subjects with similar age at a 3 T magnetic resonance scanner. A significantly reduced N-acetylaspartate concentration as well as shortened N-acetylaspartate's T2 relaxation time in the schizophrenic patient group was found. The apparent N-acetylaspartate concentration difference between healthy controls and patients with schizophrenia increased with the echo time due to a decreased N-acetylaspartate's T2 in the schizophrenic group. No group difference was found for any other metabolite concentration or metabolite/brain water relaxation time. These findings of reduced N-acetylaspartate as well as shortened N-acetylaspartate's T2 relaxation time give further evidence for microstructural white matter changes in schizophrenia. Furthermore, they elucidate why reports of a reduced N-acetylaspartate concentration in schizophrenia were not always corroborated.

Diminished brain functional magnetic resonance imaging activation in patients on opiate maintenance despite normal spatial working memory task performance.

OBJECTIVES: Despite the beneficial impact on the reduction of addictive behavior, opiate maintenance therapy has been associated with negative effects on cognitive and psychomotor functioning. This may limit the outcome of behavioral strategies, rehabilitation, and reintegration into society. The objective of the study at hand was to investigate the effect of buprenorphine and methadone maintenance therapy on visuospatial working memory performance. METHODS: Visuospatial working memory performance of 13 patients, receiving either methadone or buprenorphine, was investigated and compared to 13 control participants using functional magnetic resonance imaging. RESULTS: Altered neuronal activation was found in the patients, including brain areas associated with working memory performance and addiction. Behavioral performance on the visuospatial working memory task was similar across groups. CONCLUSIONS: Results indicate that there are no robust impairments of visuospatial capabilities in patients on opiate maintenance, but altered neuronal activation in working memory-related brain areas-due to chronic presence of opiates-may limit cognitive performance on complex cognitive tasks. Factors in therapeutic strategies that may support rehabilitation of patients' cognitive performance are discussed.

Translational magnetic resonance spectroscopy reveals excessive central glutamate levels during alcohol withdrawal in humans and rats.

BACKGROUND: In alcoholism, excessive glutamatergic neurotransmission has long been implicated in the acute withdrawal syndrome and as a key signal for dependence-related neuroplasticity. Our understanding of this pathophysiological mechanism originates largely from animal studies, but human data are needed for translation into successful medication development. METHODS: We measured brain glutamate levels during detoxification in alcohol-dependent patients (n = 47) and in healthy control subjects (n = 57) as well as in a rat model of alcoholism by state-of-the-art ¹H-magnetic magnetic resonance spectroscopy at 3 and 9.4 T, respectively. RESULTS: We found significantly increased glutamate levels during acute alcohol withdrawal in corresponding prefrontocortical regions of treatment-seeking alcoholic patients and alcohol-dependent rats versus respective control subjects. The augmented spectroscopic glutamate signal is likely related to increased glutamatergic neurotransmission because, enabled by the high field strength of the animal scanner, we detected a profoundly elevated glutamate/glutamine ratio in alcohol-dependent rats during acute withdrawal. All dependence-induced metabolic alterations normalize within a few weeks of abstinence in both humans and rats. CONCLUSIONS: Our data provide first-time direct support from humans for the glutamate hypothesis of alcoholism, demonstrate the comparability of human and animal magnetic resonance spectroscopy responses, and identify the glutamate/glutamine ratio as potential biomarker for monitoring disease progression.

Metabolic alterations in the amygdala in borderline personality disorder: a proton magnetic resonance spectroscopy study.

BACKGROUND: Emotional dysfunction in a frontolimbic network has been implicated in the pathophysiology of borderline personality disorder (BPD). The amygdala is a key region of the limbic system and plays an important role in impulsivity, affect regulation, and emotional information processing and thus is likely related to BPD symptoms. Alterations of the metabolism in the amygdala might be of interest for understanding the pathophysiology of BPD. However, the amygdala is a difficult region from which to acquire magnetic resonance spectra. We implemented a method for proton magnetic resonance spectroscopy ((1)H MRS) at 3.0 T in which we acquire data within only the small amygdala. The purpose of this study was to determine alterations of the metabolism in the amygdala in BPD patients. METHODS: Twenty-one unmedicated BPD patients and 20 age-matched healthy control participants underwent (1)H MRS to determine neurometabolite concentrations in the left amygdala. All participants underwent psychometric assessments. RESULTS: Significantly reduced total N-acetylaspartate (tNAA) and total creatine (tCr) concentrations in the left amygdala of patients with BPD were found. BPD patients with comorbid posttraumatic stress disorder (PTSD) showed lower levels of tCr compared with BPD patients without PTSD and healthy control subjects. No significant correlations between neurochemical concentrations and psychometric measures were found. CONCLUSIONS: Decreased tNAA and tCr might indicate disturbed affect regulation and emotional information processing in the amygdala of BPD patients. These findings are consistent with many functional and structural neuroimaging studies and may help to explain the greater emotional reactivity of BPD patients.

Correlation of glutamate levels in the anterior cingulate cortex with self-reported impulsivity in patients with borderline personality disorder and healthy controls.

CONTEXT: Dysfunction and deficits in the structure of the anterior cingulate cortex have been reported in borderline personality disorder (BPD). To our knowledge, there is only 1 published study to date investigating anterior cingulate cortex metabolism in subjects with BPD and co-occurring attention-deficit/hyperactivity disorder using proton magnetic resonance spectroscopy. Impulsivity is a key feature of BPD and can be related to anterior cingulate cortex function. OBJECTIVE: To investigate whether anterior cingulate cortex metabolism may be altered in BPD and correlates with BPD pathology. DESIGN: Cross-sectional proton magnetic resonance spectroscopy study. SETTING: Department of Psychosomatic Medicine and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany. PARTICIPANTS AND PATIENTS: Thirty unmedicated female subjects meeting DSM-IV criteria for BPD and 31 age-matched healthy female control participants. MAIN OUTCOME MEASURES: Neurometabolite concentrations in the anterior cingulate cortex and correlation of glutamate levels with self-reported measures of impulsivity and severity of borderline symptoms. RESULTS: Significantly higher levels of glutamate in the anterior cingulate cortex were found in subjects with BPD as compared with healthy controls. A positive correlation between glutamate concentration and the Barratt Impulsiveness Scale total score as well as between glutamate concentration and the subscore for cognitive impulsivity were observed irrespective of diagnosis. We also found a positive correlation between glutamate concentrations and dissociation as well as between glutamate concentration and subscores of the Borderline Symptom List in the patient group. CONCLUSIONS: Our results support the hypothesis that higher glutamate concentration in the anterior cingulate cortex is associated with both severity of BPD symptoms and subjective impulsivity ratings, the latter independent of BPD. Further studies should confirm the association between enhanced glutamate concentration in the anterior cingulate cortex and behavioral measures of impulsivity.