Short-term effects of electroconvulsive treatment on the uptake of 99mTc-exametazime into brain in major depression shown with single photon emission tomography

Changes in postictal cerebral perfusion are related to the duration of electroconvulsive therapy-induced seizures

OBJECTIVE

Postictal symptoms may result from cerebral hypoperfusion, which is possibly a consequence of seizure-induced vasoconstriction. Longer seizures have previously been shown to cause more severe postictal hypoperfusion in rats and epilepsy patients. We studied cerebral perfusion after generalized seizures elicited by electroconvulsive therapy (ECT) and its relation to seizure duration.

METHODS

Patients with a major depressive episode who underwent ECT were included. During treatment, 21-channel continuous electroencephalogram (EEG) was recorded. Arterial spin labeling magnetic resonance imaging scans were acquired before the ECT course (baseline) and approximately 1 h after an ECT-induced seizure (postictal) to quantify global and regional gray matter cerebral blood flow (CBF). Seizure duration was assessed from the period of epileptiform discharges on the EEG. Healthy controls were scanned twice to assess test-retest variability. We performed hypothesis-driven Bayesian analyses to study the relation between global and regional perfusion changes and seizure duration.

RESULTS

Twenty-four patients and 27 healthy controls were included. Changes in postictal global and regional CBF were correlated with seizure duration. In patients with longer seizure durations, global decrease in CBF reached values up to 28 mL/100 g/min. Regional reductions in CBF were most prominent in the inferior frontal gyrus, cingulate gyrus, and insula (up to 35 mL/100 g/min). In patients with shorter seizures, global and regional perfusion increased (up to 20 mL/100 g/min). These perfusion changes were larger than changes observed in healthy controls, with a maximum median global CBF increase of 12 mL/100 g/min and a maximum median global CBF decrease of 20 mL/100 g/min.

SIGNIFICANCE

Seizure duration is a key factor determining postictal perfusion changes. In future studies, seizure duration needs to be considered as a confounding factor due to its opposite effect on postictal perfusion.

Isotretinoin and neuropsychiatric side effects: Continued vigilance is needed

Background

Isotretinoin (13-cis-retinoic acid, marketed under the names Accutane, Roaccutane, and others) is an effective treatment for acne that has been on the market for over 30 years, although reports of neuropsychiatric side effects continue to be reported. Isotretinoin is an isomer of the active form of Vitamin A, 13-trans-retinoic acid, which has known psychiatric side effects when given in excessive doses, and is part of the family of compounds called retinoids, which have multiple functions in the central nervous system.

Methods

The literature was reviewed in pubmed and psychinfo for research related to isotretinoin and neuropsychiatric side effects including depression, suicidal thoughts, suicide, mania, anxiety, impulsivity, emotional lability, violence, aggression, and psychosis.

Results

Multiple case series have shown that successful treatment of acne with isotretinoin results in improvements in measures of quality of life and self esteem However, studies show individual cases of clinically significant depression and other neuropsychiatric events that, although not common, are persistent in the literature. Since the original cases of depression were reported to the United States Food and Drug Administration, numerous cases have been reported to regulatory agencies in the United Kingdom, France, Ireland, Denmark, Australia, Canada, and other countries, making isotretinoin one of the top five medications in the world associated with depression and other neuropsychiatric side effects. Clinicians are advised to warn patients of the risks of neuropsychiatric side effects with isotretinoin which may arise from the medication itself, and not just as a side effect of acne or youth.

Application of Noninvasive Vagal Nerve Stimulation to Stress-Related Psychiatric Disorders

BACKGROUND

Vagal Nerve Stimulation (VNS) has been shown to be efficacious for the treatment of depression, but to date, VNS devices have required surgical implantation, which has limited widespread implementation.

METHODS

New noninvasive VNS (nVNS) devices have been developed which allow external stimulation of the vagus nerve, and their effects on physiology in patients with stress-related psychiatric disorders can be measured with brain imaging, blood biomarkers, and wearable sensing devices. Advantages in terms of cost and convenience may lead to more widespread implementation in psychiatry, as well as facilitate research of the physiology of the vagus nerve in humans. nVNS has effects on autonomic tone, cardiovascular function, inflammatory responses, and central brain areas involved in modulation of emotion, all of which make it particularly applicable to patients with stress-related psychiatric disorders, including posttraumatic stress disorder (PTSD) and depression, since dysregulation of these circuits and systems underlies the symptomatology of these disorders.

RESULTS

This paper reviewed the physiology of the vagus nerve and its relevance to modulating the stress response in the context of application of nVNS to stress-related psychiatric disorders.

CONCLUSIONS

nVNS has a favorable effect on stress physiology that is measurable using brain imaging, blood biomarkers of inflammation, and wearable sensing devices, and shows promise in the prevention and treatment of stress-related psychiatric disorders.

Association between increased theta cordance and early response to ECT in late-life depression

OBJECTIVES

More than half of patients with major depression who do not respond to initial antidepressants become treatment resistant (TRD), and while electroconvulsive therapy (ECT) is effective, it involves anesthesia and other medical risks that are of concern in geriatric patients. Past studies have suggested that theta cordance (TC), a correlate of cerebral metabolism measured by electroencephalography, could guide treatment decisions related to patient selection and engagement of the therapeutic target.

METHODS/DESIGN

Eight patients with late-life treatment resistant depression (LL-TRD) underwent magnetoencephalography (MEG) at baseline and following seven sessions of ECT. We tested whether the mean and regional frontal cortex TC were able to differentiate early responders from nonresponders.

RESULTS

Five patients whose depression severity decreased by >30% after seven sessions were considered early responders. We found no baseline differences in mean frontal TC between early responders compared with nonresponders, but early responders exhibited a significant increase in TC following ECT. Further, we found that compared with nonresponders, early responders exhibited a greater change in TC specifically within the right prefrontal cortex.

CONCLUSIONS

These results support the hypothesis that increases in frontal TC are associated with antidepressant response. We expand on previous findings by showing that this change is specific to the right prefrontal cortex. Validation of this neural marker could contribute to improved ECT outcomes, by informing early clinical decisions about the acute efficacy of this treatment.

Effect of electroconvulsive therapy on gray matter volume in major depressive disorder

BACKGROUND

Although the clinical efficacy of electroconvulsive therapy (ECT) is well established, the underlying mechanisms of action remain elusive. The aim of this study was to elucidate structural changes of the brain following ECT in patients with major depressive disorder (MDD).

METHOD

Fifteen patients with MDD underwent magnetic resonance imaging scanning before and after ECT. Their gray matter volumes were compared between pre- and post-ECT.

RESULTS

There were significant volume increases after ECT in the bilateral medial temporal cortices, inferior temporal cortices, and right anterior cingulate. Further, the increase ratio was correlated with the clinical improvement measured by the Hamilton Depression Rating scale.

LIMITATION

All subjects were treated with antidepressants that could have a neurotoxic or neuroprotective effect on the brain.

CONCLUSIONS

We found that there were significant increases of gray matter volume in medial temporal lobes following ECT, suggesting that a neurotrophic effect of ECT could play a role in its therapeutic effect.

Frontocingulate dysfunction in depression: toward biomarkers of treatment response

Increased rostral anterior cingulate cortex (rACC) activity has emerged as a promising predictor of treatment response in depression, but neither the reliability of this relationship nor the mechanisms supporting it have been thoroughly investigated. This review takes a three-pronged approach to these issues. First, I present a meta-analysis demonstrating that the relationship between resting rACC activity and treatment response is robust. Second, I propose that the rACC plays a key role in treatment outcome because of its 'hub' position in the default network. Specifically, I hypothesize that elevated resting rACC activity confers better treatment outcomes by fostering adaptive self-referential processing and by helping to recalibrate relationships between the default network and a 'task-positive network' that comprises dorsolateral prefrontal and dorsal cingulate regions implicated in cognitive control. Third, I support this hypothesis by reviewing neuropsychological, electrophysiological, and neuroimaging data on frontocingulate dysfunction in depression. The review ends with a discussion of the limitations of current work and future directions.

A single photon emission computerized tomography (SPECT) study of regional cerebral blood flow in bipolar disorder

Data on functional imaging of bipolar disorder (BD) utilizing single photon emission computerized tomography (SPECT) is limited. This study assessed regional cerebral blood flow (rCBF), using (99m)Tc-ECD SPECT, among patients with BD, with mania (N=10) or depression (N=10), compared with 10 patients with unipolar depression and 10 normal controls. Regions of interest were analysed using a semi-automatic brain quantification programme. Compared to controls, patients with mania had significantly reduced perfusion mainly in the left frontal area, also in the left anterior cingulate and parietal cortices; those with bipolar depression had significantly lowered rCBF principally in the anterior temporal regions bilaterally, as well as the left parietal area. Patients with unipolar depression had significantly lowered perfusion than controls in most of the regions examined, chiefly in the anterior temporal and frontal cortices bilaterally; they also had lowered perfusion in the right anterior temporal and frontal areas, as well as the right middle temporal area and the right thalamus, compared to patients with mania. Increased severity of psychotic symptoms was associated with reduced rCBF in patients. These results indicate that altered blood flow in the frontal-subcortical systems characterises patients with BD, as well as those with unipolar depression.

Antipsychotic effect of electroconvulsive therapy is related to normalization of subgenual cingulate theta activity in psychotic depression

OBJECTIVE

Electroconvulsive therapy (ECT) is one of the most effective options available for treating depressive and psychotic symptoms in a variety of disorders. While the exact mechanism of ECT is unclear, it is known to increase metabolism and blood flow specifically in the anterior cingulate cortex (ACC). The ACC is a cortical generator of theta rhythms, which are abnormal in patients with depression and psychotic disorders. Since patients with psychotic depression are known to respond particularly robustly to ECT, we investigated whether the therapeutic effect of ECT in this population was related to normalization of abnormal theta activity in the ACC.

METHOD

We obtained 19-lead electroencephalography (EEG) data from 17 participants with psychotic depression before and 2-3 weeks after a full course of ECT. EEG data was analyzed with quantitative measures and low-resolution electromagnetic tomography (LORETA) compared to an age-adjusted normative database.

RESULTS

Quantitative EEG analyses revealed that theta band (4-7 Hz) activity was the only frequency band that changed with ECT. LORETA analyses revealed that the primary site of theta activity change was within the subgenual ACC (Brodmann area 25). There was a positive association between increased subgenual ACC theta activity and decreased psychotic symptoms. The degree of low theta activity in the subgenual ACC prior to ECT predicted the antipsychotic response of ECT.

CONCLUSIONS

The antipsychotic effect of ECT is related to normalization of subgenual ACC theta hypoactivity.

Electroconvulsive therapy and its different indications

In spite of recent developments in the pharmacotherapy of depressive disorders, the delay until clinical improvement can be achieved, and the considerable rate of nonresponse and nonremission, are major problems which remain unresolved. Electroconvulsive therapy (ECT) is a nonpharmacologic biological treatment which has been proven to be a highly effective treatment option, predominantly for depression, but also for schizophrenia and other indications. Though there is a lack of controlled investigations on long-term treatments, ECT can also be used for relapse prevention during maintenance therapies. The safety and tolerability of electroconvulsive treatment have been enhanced by the use of modified stimulation techniques and by progress in modern anesthesia. Thus, today a safe treatment can also be offered to patients with higher somatic risks. ECT still represents an important option, especially in the therapy of treatment-resistant psychiatric disorders after medication treatment failures. Earlier consideration of ECT may reduce the rate of chronic and difficult-to-treat psychiatric disorders.

The neurobiology of retinoic acid in affective disorders

Current models of affective disorders implicate alterations in norepinephrine, serotonin, dopamine, and CRF/cortisol; however treatments targeted at these neurotransmitters or hormones have led to imperfect resolution of symptoms, suggesting that the neurobiology of affective disorders is incompletely understood. Until now retinoids have not been considered as possible contributors to affective disorders. Retinoids represent a family of compounds derived from vitamin A that perform a large number of functions, many via the vitamin A product, retinoic acid. This signaling molecule binds to specific retinoic acid receptors in the brain which, like the glucocorticoid and thyroid hormone receptors, are part of the nuclear receptor superfamily and regulate gene transcription. Research in the field of retinoic acid in the CNS has focused on the developing brain, in part stimulated by the observation that isotretinoin (13-cis retinoic acid), an isomer of retinoic acid used in the treatment of acne, is highly teratogenic for the CNS. More recent work has suggested that retinoic acid may influence the adult brain; animal studies indicated that the administration of isotretinoin is associated with alterations in behavior as well as inhibition of neurogenesis in the hippocampus. Clinical evidence for an association between retinoids and depression includes case reports in the literature, studies of health care databases, and other sources. A preliminary PET study in human subjects showed that isotretinoin was associated with a decrease in orbitofrontal metabolism. Several studies have shown that the molecular components required for retinoic acid signaling are expressed in the adult brain; the overlap of brain areas implicated in retinoic acid function and stress and depression suggest that retinoids could play a role in affective disorders. This report reviews the evidence in this area and describes several systems that may be targets of retinoic acid and which contribute to the pathophysiology of depression.

Metabolic correlates of antidepressant and antipsychotic response in patients with psychotic depression undergoing electroconvulsive therapy

OBJECTIVES

Although electroconvulsive therapy (ECT) is a very effective treatment of depression and psychosis, the mechanisms by which this occurs are not fully delineated. The objective of this study was to investigate the functional alterations in brain metabolism in response to ECT through the use of positron emission tomography assessment of cerebral glucose metabolism before and after a course of ECT.

METHODS

Ten subjects with psychotic depression were studied with positron emission tomography using [F]fluorodeoxyglucose before and between 2 and 3 weeks after a course of ECT. Statistical parametric mapping and region of interest analyses of the anterior cingulate cortex (ACC) subregions (dorsal, rostral, subcallosal, and subgenual) and hippocampus were used to determine glucose metabolic changes from ECT. The Hamilton Depression Rating Scale and the Scale for Assessing Positive Symptoms were the primary measures used for assessing clinical changes from ECT.

RESULTS

Electroconvulsive therapy led to significant increases in the left subgenual ACC and hippocampal metabolism, which were directly correlated with each other and to a reduction in depression as measured by total Hamilton Depression Rating Scale scores. Better antidepressant responders had increased, whereas poorer responders had a decreased left subgenual ACC and hippocampal metabolism. The decrease in positive symptoms was also correlated with increased left hippocampal metabolism.

CONCLUSIONS

The antidepressant effect of ECT was correlated with increased metabolism in the left subgenual ACC and hippocampus, whereas the antipsychotic effect of ECT was only correlated with increased left hippocampal metabolism. This finding has implications to better understand the mechanism of antidepressant and antipsychotic effects of ECT.

Imaging onset and propagation of ECT-induced seizures

PURPOSE

Regions of seizure onset and propagation in human generalized tonic-clonic seizures are not well understood. Cerebral blood flow (CBF) measurements with single photon emission computed tomography (SPECT) during electroconvulsive therapy (ECT)-induced seizures provide a unique opportunity to investigate seizure onset and propagation under controlled conditions.

METHODS

ECT stimulation induces a typical generalized tonic-clonic seizure, resembling spontaneous generalized seizures in both clinical and electroencephalogram (EEG) manifestations. Patients were divided into two groups based on timing of ictal (during seizure) SPECT tracer injections: 0 s after ECT stimulation (early group), and 30 s after ECT (late group). Statistical parametric mapping (SPM) was used to determine regions of significant CBF changes between ictal and interictal scans on a voxel-by-voxel basis.

RESULTS

In the early injection group, we saw increases near the regions of the bitemporal stimulating electrodes as well as some thalamic and basal ganglia activation. With late injections, we observed increases mainly in the parietal and occipital lobes, regions that were quiescent 30 s prior. Significant decreases occurred only at the later injection time, and these were localized to the bilateral cingulate gyrus and left dorsolateral frontal cortex.

CONCLUSIONS

Activations in distinct regions at the two time points, as well as sparing of intermediary brain structures, suggest that ECT-induced seizures propagate from the site of initiation to other specific brain regions. Further work will be needed to determine if this propagation occurs through cortical-cortical or cortico-thalamo-cortical networks. A better understanding of seizure propagation mechanisms may lead to improved treatments aimed at preventing seizure generalization.

Transcranial and deep brain stimulation approaches as treatment for depression

Given that a considerable portion of depressed patients does not respond to or remit during pharmacotherapy, there is increasing interest in non-pharmacological strategies to treat depressive disorders. Several brain stimulation approaches are currently being investigated as novel therapeutic interventions beside electroconvulsive therapy (ECT), a prototypic method in this field with proven effectiveness. These neurostimulation methods include repetitive transcranial magnetic stimulation (rTMS), magnetic seizure therapy (MST), vagus nerve stimulation (VNS), deep brain stimulation (DBS) and transcranial direct current stimulation (tDCS). It is via different neuroanatomically defined "windows" that the various approaches access the neuronal networks showing an altered function in depression. Also, the methods vary regarding their degree of invasiveness. One or the other method may finally achieve antidepressant effectiveness with minimized side effects and constitute a new effective treatment for major depression.

Changes in regional cerebral blood flow during acute electroconvulsive therapy in patients with depression: positron emission tomographic study

BACKGROUND

Although electroconvulsive therapy (ECT) is widely used to treat psychiatric disorders such as depression, its precise neural mechanisms remain unknown.

AIMS

To investigate the time course of changes in cerebral blood flow during acute ECT.

METHOD

Cerebral blood flow was quantified serially prior to, during and after acute ECT in six patients with depression under anaesthesia using [(15)O]H(2)O positron emission tomography (PET).

RESULTS

Cerebral blood flow during ECT increased particularly in the basal ganglia, brain-stem, diencephalon, amygdala, vermis and the frontal, temporal and parietal cortices compared with that before ECT. The flow increased in the thalamus and decreased in the anterior cingulate and medial frontal cortex soon after ECT compared with that before ECT.

CONCLUSIONS

These results suggest a relationship between the centrencephalic system and seizure generalisation. Further, they suggest that some neural mechanisms of action of ECT are mediated via brain regions including the anterior cingulate and medial frontal cortex and thalamus.

Regional cerebral blood flow changes in depression after electroconvulsive therapy

A large number of studies have documented regional cerebral blood flow (rCBF) abnormalities in depression. A smaller yet significant number of studies have examined changes in rCBF before and after treatment. The findings, however, have been variable with regard to changes before and after electroconvulsive therapy (ECT). A consecutive series of patients (n=10) with drug-resistant major depressive episode according to DSM-IV with 17-item Hamilton Rating Scale for Depression (HRSD) scores greater than or equal to 14 gave their informed consent and were studied with technetium-99m ethyl cysteinate dimer single-photon emission computed tomography (99mTc-ECD SPECT) before and after a course of ECT. The results were analyzed with statistical parametric mapping version 99. No region showed significant positive correlations between rCBF patterns of changes and HRSD changes, but three clusters emerged as showing significant negative correlations. These regions corresponded with left frontopolar gyrus, left amygdala, globus pallidus and nucleus accumbens, and left superior temporal gyrus. It was speculated that ECT affected both the prefrontal cortex, commonly assumed to be involved in depression, and the amygdala, known to play a central role in the processing of emotional stimuli, through the limbic-cortical-striatal-pallidal-thalamic circuit.

Improved anatomic delineation of the antidepressant response to partial sleep deprivation in medial frontal cortex using perfusion-weighted functional MRI

This study used functional magnetic resonance imaging (fMRI) to clarify the sites of brain activity associated with the antidepressant effects of sleep deprivation (SD). We hypothesized: 1) depressed responders' baseline ventral anterior cingulate (AC) perfusion will be greater than that of nonresponders and controls; 2) following partial sleep deprivation (PSD), ventral AC perfusion will significantly decrease in responders only. Seventeen unmedicated outpatients with current major depression and eight controls received perfusion-weighted fMRI and structural MRI at baseline and following 1 night of late-night PSD. Talairach-transformed gray matter masks were merged with Talairach Daemon-based region of interest (ROI) templates. Baseline left ventral AC (LVAC) perfusion was greater in responders than nonresponders. There was no difference involving the medial frontal cortex. Responders' LVAC perfusion dropped from baseline to PSD scans compared with nonresponders and controls, as did perfusion in the right dorsal AC. In the patient group as a whole, decrease in LVAC perfusion from baseline to PSD scans correlated directly with the decrease in the modified 17-item Hamilton Depression Rating Scale (HDRS17) between baseline and PSD conditions. These data--the first using fMRI--show greater anatomic specificity than previous findings of SD and depression in linking decreased brain activity in this area with clinical improvement.

Does amygdalar perfusion correlate with antidepressant response to partial sleep deprivation in major depression?

This study used functional MRI (fMRI) to clarify the sites of brain activity associated with the antidepressant effects of sleep deprivation (SD). We hypothesized: (1) baseline perfusion in right and left amygdalae will be greater in responders than in nonresponders; (2) following partial sleep deprivation (PSD), perfusion in responders' right and left amygdalae would decrease. Seventeen unmedicated outpatients with current major depression and eight controls received perfusion-weighted fMRI and structural MRI at baseline and following 1 night of late-night PSD. Baseline bilateral amygdalar perfusion was greater in responders than nonresponders. Clusters involving both amygdalae decreased from baseline to PSD specifically in responders. Right amygdalar perfusion diverged with PSD, increasing in nonresponders and decreasing in responders. These novel amygdalar findings are consistent with the overarousal hypothesis of SD as well as other functional imaging studies showing increased baseline amygdalar activity in depression and decreased amygdalar activity with remission or antidepressant medications.

Time course of cerebral blood flow changes following electroconvulsive therapy in depressive patients-measured at 3 time points using single photon emission computed tomography

Although electroconvulsive therapy (ECT) has been employed for treating depression for more than 60 years, its mechanisms of action are yet unknown. To clarify the ECT effects on brain function, we examined cerebral blood flow (CBF) using single photon emission computed tomography at 3 time points--few days before an ECT course (Pre) and approximately 5 days (Post 1) and 1 month (Post 2) after the last ECT session. Eight depressive patients completed the study. In all the patients, the depressive symptoms improved after the ECT course, and major cognitive impairment was not observed at any time point. At Pre, the regional CBF (rCBF) in the widespread areas in the frontal lobe and limbic regions including cingulate cortex and parahippocampal gyrus was lower in the patients than in the normal controls. At Post 1 and Post 2, the rCBF in the frontal and limbic regions continued to be lower in the patients than in the controls although the successive recovery of decreased rCBF in the frontal region was observed. Regarding the time course among the patients, the rCBF in the right medial frontal region significantly increased (toward normal) at Post 2, not at Post 1. These findings suggest that depressive patients have decreased CBF in the frontal and limbic regions, and the medial frontal region plays a crucial role in ECT and recovery from depression. Further, patients who have undergone ECT treatment for depression should be carefully observed because brain functions continue to change even after a successful ECT course.

[Value of diagnostic imaging in evaluation of electroconvulsive therapy]

Magnetic resonance imaging (MRI), positron emission tomography (PET), and single photon emission computed tomography (SPECT) may be able to investigate the clinical efficacy and underlying neuronal processes of electroconvulsive therapy (ECT). The following review focuses on neuroimaging in ECT. Neuroimaging findings support that ECT does not result in significant macroscopic structural changes. However, in patients with subtle structural changes such as subcortical lesions and dilatation of lateral ventricles before ECT, the possibilities of poor therapeutic outcome, increased incidence of delirium, and longer-lasting cognitive deficits should be considered. Functional studies show reduced blood flow and glucose metabolism during the first days after ECT. Afterwards, their normalization can be observed, which seems to correlate to clinical improvement. The importance of this suppression effect needs to be further elucidated. Future studies of receptor systems and longitudinal studies will open new perspectives in future imaging research.

Pretreatment neurophysiologic function and ECT response in depression

OBJECTIVES

Recent brain imaging studies have provided evidence that brain function assessed prior to treatment of depression may be associated with eventual treatment response. The present study tested the hypothesis that brain activity in midline apical quantitative EEG (QEEG) electrodes would be associated with therapeutic response to electroconvulsive therapy (ECT).

METHODS

Ten treatment-refractory patients with unipolar or bipolar depression received a Hamilton Rating Scale for Depression (Ham-D) at baseline, during, and following ECT treatment. Resting, eyes-closed, 35-lead QEEG recordings were done 1 day before the initial ECT treatment. Data were analyzed using QEEG power and cordance.

RESULTS

The mean of the theta-band pretreatment cordance from the central brain region was strongly associated with percentage decrease in Ham-D score over the course of treatment (r = 0.80, P = 0.005). QEEG cordance from other brain regions and power from all brain regions did not show an association with clinical improvement.

CONCLUSIONS

Depressed subjects with higher pretreatment central cordance appear to be more likely to experience therapeutic benefits of ECT. The location of central electrodes over the cingulate cortex may indicate that pretreatment cingulate activity is associated with response to ECT.

Changes in brain metabolism associated with remission in unipolar major depression

OBJECTIVE

Functional brain correlates of remission in patients with major depressive disorder (MDD) are measured with positron emission tomography (PET) and 18F-fluorodeoxyglucose.

METHOD

Glucose metabolism was measured in patients (n = 41) with moderate to severe MDD during acute depression and in the remitted state defined as a period of asymptomatic condition over 12 weeks. Data analyses used a region-of-interest (ROI) approach and statistical parametric mapping (SPM).

RESULTS

There were significant decreases in metabolism upon remission with respect to the baseline scan in left prefrontal, anterior temporal and anterior cingulate cortex and bilateral thalamus (SPM analysis) and bilateral putamen and cerebellum (SPM and ROI analyses). There was a significant asymmetry in prefrontal and anterior cingulate cortex metabolism with lower metabolism in the left hemisphere that persisted despite clinical remission.

CONCLUSION

These findings support the hypothesis that selective monoamine reuptake inhibition leads to an attenuation of a brain circuit that mediates depressive symptomatology.

Bilateral near-infrared monitoring of the cerebral concentration and oxygen-saturation of hemoglobin during right unilateral electro-convulsive therapy

Reductions in right prefrontal cerebral blood flow have been correlated with symptomatic improvement in depressed individuals receiving electroconvulsive therapy (ECT). Non-invasive near infrared spectroscopy has previously been shown to reliably measure changes in cerebral hemoglobin concentrations and oxygen saturation. In this study, we measured the concentration and oxygen saturation of hemoglobin on the right and left frontal brain regions of nine patients during right unilateral ECT. In all patients, we have found that the electrically induced seizure causes a stronger cerebral deoxygenation on the side ipsilateral to the electrical current (-21+/-5%) with respect to the contralateral side (-6+/-4%). On the brain side ipsilateral to the ECT electrical discharge, we have consistently observed a discharge-induced decrease in the total hemoglobin concentration, i.e. in the cerebral blood volume, by -7+/-3 microM, as opposed to an average increase by 6+/-3 microM on the contralateral side. The ipsilateral decrease in blood volume is assigned to a vascular constriction associated with the electrical discharge, as indicated by the observed decrease in cerebral oxy-hemoglobin concentration and minimal change in deoxy-hemoglobin concentration during the electrical discharge on the side of the discharge. These findings provide indications about the cerebral hemodynamic/metabolic mechanisms associated with ECT, and may lead to useful parameters to predict the individual clinical outcome of ECT.

Focal network involvement in generalized seizures: new insights from electroconvulsive therapy

Generalized seizures are commonly thought to involve the entire brain homogeneously. However, recent evidence suggests that selective cortical-subcortical networks may be crucial for the initiation, propagation, and behavioral manifestations of generalized seizures, while other brain regions are relatively spared. Here we review previous studies, and describe a new human model system for the investigation of generalized seizures: single-photon emission computed tomography, ictal-interictal difference imaging of generalized tonic-clonic seizures induced by electroconvulsive therapy (ECT). Bitemporal ECT activates focal bilateral frontotemporal and parietal association cortex, sparing other regions; bifrontal ECT activates mainly prefrontal cortex; while in right unilateral ECT the left frontotemporal region is relatively spared. Associated midline subcortical networks are also involved. Focal verbal memory deficits parallel the focal regions involved in these neuroimaging studies. Further studies of this kind may elucidate specific networks in generalized tonic-clonic seizures, providing targets for new therapeutic interventions in epilepsy.

Anatomical MRI study of basal ganglia in major depressive disorder

The basal ganglia form a part of the brain neuroanatomic circuits that may be involved in mood regulation. Decreases in basal ganglia volumes have been previously reported in major depressive disorder patients in comparison to healthy controls. In this study, we measured caudate, putamen, and globus pallidus volumes in 25 patients with major depressive disorder (4 M; age+/-S.D.=41+/-11 years) and 48 healthy controls (29 M; age+/-S.D.=35+/-10 years), using high-resolution magnetic resonance imaging (MRI), in an attempt to replicate prior findings. Unlike most previous studies, we did not find significant differences between patient and control groups in basal ganglia volumetric measures. Nonetheless, there was a significant interaction between diagnosis and cerebral hemisphere, with MDD patients showing decreased asymmetry in globus pallidus volumes in comparison with healthy controls. Furthermore, in the patient group, left putamen volumes correlated inversely with length of illness, and left globus pallidus volume correlated directly with number of prior depressive episodes. These findings suggest that abnormalities in lateralization and possibly neurodegenerative changes in basal ganglia structures participate in the pathophysiology of major depressive disorder.

[Check-ups with brain SPECT in electroconvulsive therapy in patients with severe drug-resistant depressive episodes and Parkinson's disease]

We have studied three women (66,72 and 72 years) with Parkinson's disease of 11, 6 and 21 years of evolution and drug-resistant severe depressive episodes treated with electroconvulsive therapy (ECT). We have performed a brain SPECT (99mTc-HMPAO) before and after the ECT. The clinical improvement of the severe depressive episodes were measured using the Hamilton score. The first patient did not experience any clinical improvement (Hamilton score 42 to 42). In this patient the brain SPECT before treatment presented a reduced perfusion in the posterior parietal region, anterior cingulate cortex and medial frontal and parietal cortex. After the treatment, the brain SPECT did not present significant variations. The second patient presented a moderate clinical improvement (Hamilton score 46 to 36) and also presented moderate improvement in the neurological symptoms. The brain SPECT before the treatment showed reduced perfusion in the left temporal cortex and medium-posterior parietal cortex. After the treatment, it also did not reflect significant variations. The third patient experienced a very good response to the ECT sessions (Hamilton score 45 to 10) and also an improvement regarding the neurological symptoms. This patient presented a reduced perfusion in the medium-posterior parietal regions in the brain SPECT performed before the treatment; these regions presented a moderate improvement in the brain SPECT performed after the treatment. The patient who presented a significant neurological and psychiatric improvement also presented an improvement in the perfusion of the decreased areas in the brain SPECT and showed fewer alterations in the baseline brain SPECT compared with the others. The brain SPECT could have a prognostic (and confirmation) role regarding clinical improvement induced by ECT in resistant depression in Parkinson's disease. ECT is an alternative in treatment of severe depressive drug-resistant episodes associated to the Parkinson's disease.

Reduced volume of orbitofrontal cortex in major depression

BACKGROUND

Functional neuroimaging studies have implicated dysfunction of orbitofrontal cortex in the symptoms of depression, and a recent postmortem study of depressed patients found reduced density of neurons and glia in this area. The purpose of this study was to measure volume of orbitofrontal cortex and other frontal cortical subregions in patients with major depression.

METHODS

Magnetic resonance imaging was used to measure volume of the orbitofrontal cortex and other frontal cortical regions in patients with major depression in remission (n = 15) and comparison subjects (n = 20).

RESULTS

Patients with depression had a statistically significant 32% smaller medial orbitofrontal (gyrus rectus) cortical volume, without smaller volumes of other frontal regions including anterior cingulate Brodmann's area 24 (subgenual gyrus), anterior cingulate Brodmann's area 32, subcallosal gyrus (Brodmann's area 25), or whole brain volume. The findings were significant after statistically controlling for brain size.

CONCLUSIONS

These findings are consistent with smaller orbitofrontal cortical volume in depression.

Changes in regional cerebral blood flow abnormalities in late-life depression following response to electroconvulsive therapy

The impact of electroconvulsive therapy (ECT) on the regional cerebral blood flow (rCBF) abnormalities in late-life depression is still unknown and the clinical significance of these findings in late-life depression has not been fully discussed. Using single photon emission computed tomography (SPECT) with 99mTc-hexamethylpropylene amine oxime (99mTc-HMPAO), we examined the changes of rCBF patterns in nine late-life patients with major depressive episodes before and following response to ECT compared with nine age- and sex-matched healthy volunteers. Statistical comparisons were made on both region-of-interest (ROI) and voxel-by-voxel bases. In ROI-based analyses, a mean rCBF was significantly decreased in the patients before ECT compared with the control, significantly increased (normalized) in the patients 2 weeks after ECT compared with that before ECT, and still increased in the patients 12 weeks after ECT compared with that before ECT. In voxel-by-voxel analyses, a significant rCBF reduction was found in the bilateral pre- and subcallosal anterior cingulate cortex, the bilateral caudal orbitofrontal cortex, the right insular cortex and the right posterior middle frontal gyrus in patients before ECT compared with the control, and similar rCBF patterns were shown at 2 weeks and 12 weeks after ECT. We propose the hypothesis that a mean rCBF reduction may have a state-related property while persistent anterior paralimbic hypoperfusion may have a trait-like property, which relates to the relapse vulnerability as well as a tendency toward medication failure and illness chronicity in late-life depression.

SPECT and neuropsychological performance in severe depression treated with ECT

BACKGROUND

In severe depression, studies of regional cerebral blood flow (rCBF) by SPECT have not produced uniform results. The association between changes in SPECT and electroconvulsive therapy (ECT) has shown somewhat conflicting data. No data are available on benzodiazepine receptor function SPECT studies in ECT.

METHODS

Twenty drug-resistant adult inpatients fulfilling the DSM-IIIR criteria for major depression were studied by SPECT (rCBF by relative ECD uptake in all, and benzodiazepine receptor function by iomazenil uptake in five subjects) before and 1 week after clinically successful bitemporal ECT. Clinical and neuropsychological test scores were used as references for the possible changes in SPECT.

RESULTS

An increased perfusion after ECT was observed in right temporal and bilateral parietal cortices, whereas no reductions in relative ECD uptake were seen after ECT. Iomazenil-SPECT revealed a highly significant increase in the benzodiazepine receptor uptake in all studied cortical regions except temporal cortices.

CONCLUSIONS

Clinically successful ECT was associated with changes in vascular perfusion and GABAergic neurotransmission, providing new evidence for the mechanism of action of ECT and for the neurobiology of severe drug-resistant depression.

Subtypes of memory dysfunction associated with ECT: characteristics and neurobiological bases

Electroconvulsive therapy (ECT) is an effective treatment for a variety of psychiatric syndromes. However, one of its adverse secondary effects is neurocognitive dysfunction. The aim of this paper is to review different subtypes of memory dysfunction associated with ECT from a neuropsychological perspective. Declarative memory is clearly impaired after ECT. Immediate memory, however, is broadly preserved. Few studies have addressed procedural and incidental memory. Selective memory is impaired, probably due to the disruption of specific brain regions. Some of the possible neurobiological bases of ECT memory dysfunction are discussed in this paper. Synaptic plasticity, the cerebral neurotransmission system, and cerebral metabolism are examined in relation to the dysfunction and subsequent recovery of each memory subtype.

Study of the influence of electroconvulsive therapy on the regional cerebral blood flow by HMPAO-SPECT

STUDY OBJECTIVE

The aim of this preliminary study is to investigate the regional blood flow in response to ECT (electroconvulsive therapy) and to identify any responsive-pattern to the treatment.

STUDY DESIGN

Single longitudinal prospective study of cohorts.

SUBJECTS

For this preliminary study ten patients, female sex, mean age 70.8 years with major mood disorder (CID-10 investigation criteria) were studied after signature consent.

INTERVENTIONS

The intervention consisted in the administration of bilateral brief pulse ECT three times a week, during 6 to 12 sessions according to the standards of the Psychiatric Department of the Santiago Hospital in Victoria.

MEASUREMENT

Clinical evaluation of depression was evaluated by Hamilton Depression Scale, Montgomery and Asberg Scale, Newcastle Scale and regional cerebral blood flow (rCBF) using the HMPAO-SPECT.

RESULTS

The pattern of distribution on the regional cerebral flow during the ECT showed changes from the basal pattern in all patients. All patients had a relative increased perfusion of the temporal lobes and basal ganglia. Other changes from the basal study were areas of decreased perfusion of the occipital lobe (6 patients) and parietal lobe (3 patients).

CONCLUSIONS

Brain perfusion SPECT study of the patients with major depression shows changes during ECT. Further analysis are needed to understand the relationship between mechanisms of treatment and recovery in affective illness.

Perfusion brain SPECT and statistical parametric mapping analysis indicate that apathy is a cingulate syndrome: a study in Alzheimer's disease and nondemented patients

Apathy is the most frequent behavioral symptom in Alzheimer's disease and is also frequently reported in other brain organic disorders occurring in the elderly. Based on the literature, we hypothesized that apathy was related to an anterior cingulate hypofunction. Forty-one subjects were studied. According to ICD 10 diagnostic criteria, 28 patients had Alzheimer dementia (demented: diagnostic group 1), and 13 had organic personality disorders or mild cognitive impairment not attributable to dementia (nondemented: diagnostic group 2). Apathy was evaluated by the Neuro-Psychiatric Inventory. As a result each diagnostic group was divided into two symptomatic subgroups: apathetic or nonapathetic. Brain perfusion was measured by (99m)Tc-labeled bicisate (ECD) brain SPECT and the images were compared using Statistical Parametric Mapping (SPM96). We began by comparing apathetic vs nonapathetic patients, whatever their diagnostic group (whole population), then analyzed them within each group. Twenty-one subjects were apathetic (14 in group 1 and 7 in group 2) and 20 were not (14 in group 1 and 6 in group 2). For the whole population, the Z map showed a significant decrease in ECD uptake for the apathetic patients in the anterior cingulate (P < 0.002) bilaterally. This area was also identified as hypoactive by SPM analysis in the demented (P < 0.035) and in the nondemented (P < 0.02) apathetic patient groups. Finally, conjunction analysis indicated that the anterior cingulate was the common hypoactive structure of the two apathetic subgroups (Z = 4.35, P < 0.0009). These results point to a close relationship between apathy and the anterior cingulate region.

Structural and functional neuroimaging of electroconvulsive therapy and transcranial magnetic stimulation

Neuroimaging has long been utilized to provide a measure of the effects of electroconvulsive therapy (ECT) on brain structure and function as well as to better understand its mechanisms of action. In a similar fashion, functional neuroimaging may provide the means to elucidate both the underlying neurobiological effects and therapeutic potential of transcranial magnetic stimulation (TMS). This article will review findings of neuroimaging studies of both TMS and ECT, concentrating on how such studies may help guide treatment.

A preliminary study of the effects of electroconvulsive therapy on regional brain glucose metabolism in patients with major depression

Animal studies have shown that a course of electroconvulsive shock (ECS) leads to a significant reduction in glucose metabolism in rat brains 1 day after the last ECS. In humans, of the two positron emission tomography (PET) studies that assessed the effects of a course of electroconvulsive therapy (ECT) on brain glucose metabolism in depressed patients, one reported no change while the other found a trend for reduction in glucose metabolism in frontal cortical region 24 hours after last ECT. The changes in glucose metabolism detected 24 hours after the last ECS/ECT treatment might simply be due to subacute effects of a seizure. We hypothesized that the changes in brain metabolism that persist 1 week after a course of ECT are more likely to underlie the therapeutic effects of ECT. We, therefore, investigated the effects of a course of ECT on brain glucose metabolism 1 week after last ECT by using PET and [18F]fluorodeoxyglucose (FDG). Six patients who met DSM-IV criteria for a diagnosis of major depressive disorder (unipolar), and were referred for ECT as the clinically indicated treatment were recruited. They underwent two PET scans, one prior to first ECT and the second a week after last ECT. The number of ECT treatments subjects received ranged from 8 to 12 with a mean of 11. Five out of six patients responded to the ECT treatment. Cerebral metabolic rates for glucose were slightly lower in most regions post treatment compared with pretreatment but the differences were not statistically significant. Similarly, there was no significant correlation between changes in regional cerebral metabolic rates for glucose (rCMRglc) and changes in Hamilton Depression Rating Scale (HAM-D 21-item) scores. Our results might suggest that rCMRglc rates are not altered 1 week after a therapeutic course of ECT in depressed patients. Further studies using new generation PET scanners, which have a higher resolution, in larger numbers of depressed patients, are clearly needed before firm conclusions can be drawn.

The functional neuroanatomy of mood disorders

Mood disorders may be associated with global and regional changes in cerebral blood flow and metabolism. The accumulated functional neuroimaging findings in mood disorders were reviewed in order to examine a proposed neuroanatomic model of pathophysiology. Global cerebral blood flow and glucose metabolism appear normal, but may be decreased in late-life depression. Regional cerebral blood flow and glucose metabolism deficits are present, and may be indicators of brain regions participating in neuroanatomic circuits involved in mood disorders. Decreased pre-frontal cortex blood flow and metabolism in depressed unipolar and bipolar patients are the most consistently replicated findings, and correlate with severity of illness. Basal ganglia abnormalities have been found in depressed unipolar and bipolar patients, involving decreased blood flow and metabolism. Temporal lobe abnormalities are present in bipolar disorder patients, and perhaps unipolar depression. There is conflicting evidence of abnormalities in other limbic regions. Cognitive impairment may correlate with decreased metabolism in frontal and cerebellar areas. The relationship between functional neuroimaging findings and clinical course, and therefore state and trait characteristics, has not been systematically investigated. Antidepressant medications, but not ECT, seem to reverse some of the identified functional brain changes in the depressed state. The structural, neurotransmitter and neuropathological correlates of these functional abnormalities are yet to be determined. Functional abnormalities in frontal, subcortical and limbic structures appear to be part of the pathophysiology of mood disorders.

A review of functional neuroimaging in mood disorders: positron emission tomography and depression

OBJECTIVE

To examine the progress of positron emission tomography (PET) as a tool for understanding the psychobiology of mood disorders, particularly major depression and bipolar disorder.

METHOD

Review of the literature on functional imaging of mood disorders.

RESULTS

Functional imaging techniques have been used in psychiatric research as a noninvasive method to study the behaviour and function of the brain. Techniques used so far have involved the manipulation of emotion in healthy volunteers, the evaluation of depressed (unipolar and bipolar as well as secondary depression), manic, and normal subjects under resting and various activation conditions, such as cognitive activation, acute pharmacological challenge, and chronic thymoleptic treatments. As a result, functional imaging studies tend to support abnormalities in specific frontal and limbic regions.

CONCLUSION

Different PET methods demonstrate consistent abnormalities in the prefrontal, cingulate, and amygdala regions. These findings are in agreement with past animal and clinical anatomical correlates of mood and emotions.

Neuropsychological and neuroimaging evidence for the involvement of the frontal lobes in depression

The onset and reversibility of major depression is likely to be explained by diffuse neuromodulatory mechanisms rather than permanent abnormalities of connectivity and neurotransmission. However, the expression of mood state appears to involve fronto-striatal mechanisms. Lesions of the ventral frontal cortex give rise to profound modification of affect and behaviour not explained by effects on current intellectual function. These may represent the most extreme possible disturbances of emotional experience. Neuropsychological testing in major depression shows evidence of slowing in motor and cognitive domains with additional prominent effects on mnemonic function most marked in the elderly. Structural imaging with X-ray computed tomography or magnetic resonance imaging in older patients with major depression shows evidence of structural abnormality compared with controls. These findings are not highly localizing but they tend to confirm the role of cognitive impairment as an important age-related risk factor for major depression. Perfusion or metabolic imaging reflects both reversible changes in function and permanent loss of active neurones. The usual finding has been reductions in anterior brain structures in major depression. Hypoperfusion tends to be greatest in frontal, temporal and parietal areas and most extensive in older (male) patients; high Hamilton scores tend to be associated with reduced uptake. There have also been correlations in the cingulate cortex between increased perfusion and other aspects of the mental state. In general, reductions in frontal areas may be more likely in patients with impoverished mental states. The more prominent impairments of memory are likely to be associated with the finding of impaired temporal function or with a more diffuse failure of neuromodulation.

The role of the cingulate gyrus in depression: from functional anatomy to neurochemistry

Depressive episodes as reversible mental states are likely to be associated with equally reversible brain states. These can be examined with a variety of functional imaging methods using repeated measures designs. Studies using such an approach are reviewed. Changes in medial frontal, and in particular, cingulate cortex are reported in a majority of studies. Similarities and differences between different study results are discussed on the background of the functional neuroanatomy of the anterior cingulate, taking into account a variety of neurotransmitter systems. It is concluded that neuroimaging techniques are starting to equip us to conceptualize functional changes in the limbic loop containing the anterior cingulate as the common denominator of change and therapy effects in depressive states.