Treatment of Refractory Bipolar Depression With Stereotactic Radiosurgery Targeting the Subgenual Cingulate Cortex

Background The subgenual cingulate cortex (SGC) has been identified as a key structure within multiple neural circuits whose dysfunction is implicated in the neurobiology of depression. Deep brain stimulation in the SGC is thought to reduce and normalize local metabolism, causing normalization of circuit behavior and an improvement in depressive symptoms. We hypothesized that nonablative stereotactic radiosurgery (SRS) to the SGC would reduce local metabolism and reduce the severity of depression in patients with treatment-resistant bipolar depression. Methods Under the FDA's Humanitarian Device Exemption program, patients were screened for inclusion and exclusion criteria. Three volunteers meeting the criteria provided informed consent. Bilateral SGC targets were irradiated to a maximum dose of 75 Gy in one fraction. Subjects were followed for one year following the procedure with mood assessments (Hamilton Depression Rating Scale (HDRS), Clinical Global Impression-Improvement, Clinical Global Impression-Severity, and Young Mania Rating Scale), neurocognitive testing (Delis-Kaplan Executive Function System, Wechsler Adult Intelligence Scale III digit span, and California Verbal Learning Test II), and imaging. Further imaging was completed approximately two years after the procedure. Clinical improvement was defined as a ≥50% reduction in HDRS. Results Two of the three subjects showed clinical improvement in depressive symptoms during the follow-up period, while one subject showed no change in symptom severity. One of three subjects was hospitalized for the emergence of an episode of psychotic mania after discontinuing antipsychotic medications against medical advice but promptly recovered with the reinstitution of an antipsychotic. Sequential assessments did not reveal impairment in any cognitive domain assessed. For one of the three subjects, MRI imaging showed evidence of edema at 12 months post-SRS, which resolved at 22 months post-procedure. In a second of three patients, there was evidence of local edema at the target site at long-term follow-up. All imaging changes were asymptomatic. Conclusion Radiosurgical targeting of the SGC may be a noninvasive strategy for the reduction of severe depression in treatment-resistant bipolar disorder. Two out of three patients showed clinical improvement. While these results are promising, further study, including improvements in target selection and dosing considerations, is needed.

Stanford Accelerated Intelligent Neuromodulation Therapy for Treatment-Resistant Depression

OBJECTIVE

New antidepressant treatments are needed that are effective, rapid acting, safe, and tolerable. Intermittent theta-burst stimulation (iTBS) is a noninvasive brain stimulation treatment that has been approved by the U.S. Food and Drug Administration for treatment-resistant depression. Recent methodological advances suggest that the current iTBS protocol might be improved through 1) treating patients with multiple sessions per day at optimally spaced intervals, 2) applying a higher overall pulse dose of stimulation, and 3) precision targeting of the left dorsolateral prefrontal cortex (DLPFC) to subgenual anterior cingulate cortex (sgACC) circuit. The authors examined the feasibility, tolerability, and preliminary efficacy of Stanford Accelerated Intelligent Neuromodulation Therapy (SAINT), an accelerated, high-dose resting-state functional connectivity MRI (fcMRI)-guided iTBS protocol for treatment-resistant depression.

METHODS

Twenty-two participants with treatment-resistant depression received open-label SAINT. fcMRI was used to individually target the region of the left DLPFC most anticorrelated with sgACC in each participant. Fifty iTBS sessions (1,800 pulses per session, 50-minute intersession interval) were delivered as 10 daily sessions over 5 consecutive days at 90% resting motor threshold (adjusted for cortical depth). Neuropsychological testing was conducted before and after SAINT.

RESULTS

One participant withdrew, leaving a sample size of 21. Nineteen of 21 participants (90.5%) met remission criteria (defined as a score <11 on the Montgomery-Åsberg Depression Rating Scale). In the intent-to-treat analysis, 19 of 22 participants (86.4%) met remission criteria. Neuropsychological testing demonstrated no negative cognitive side effects.

CONCLUSIONS

SAINT, an accelerated, high-dose, iTBS protocol with fcMRI-guided targeting, was well tolerated and safe. Double-blinded sham-controlled trials are needed to confirm the remission rate observed in this initial study.

Improvement in quality of life with left prefrontal transcranial magnetic stimulation in patients with pharmacoresistant major depression: acute and six month outcomes

BACKGROUND

Transcranial magnetic stimulation (TMS) is a safe and effective treatment for major depression. We describe quality of life (QOL) outcomes from acute treatment with TMS, and describe the durability of benefit across 24-weeks.

METHODS

Three hundred and one medication-free patients with pharmacoresistant major depression were randomized to active or sham TMS in a 6-week controlled trial. Nonresponders to the 6-week blinded phase of the study were enrolled in a 6-week open-label study without unblinding the prior treatment assignment. Responders and partial responders to both the blinded (active or sham treatment) or open acute treatment phases were tapered off TMS over three weeks, while initiating maintenance antidepressant medication monotherapy. These subjects entered the 24-week study to examine the durability of response to TMS. The Medical Outcomes Study-36 Item Short Form (SF-36) and the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q) were used to measure overall function and QOL. During the 24-week durability of effect study, QOL assessments were done at study entry and at the end of 24-weeks.

RESULTS

Statistically significant improvement in both functional status and QOL outcomes was observed in patients treated with active TMS compared with sham TMS during the acute phase of the randomized, sham-controlled trial. Similar benefits were observed in patients who entered the open-label extension study. These improvements were sustained across the 24-week follow up study.

CONCLUSIONS

Acute treatment with TMS improved functional status and QOL outcomes in patients with major depression. This clinical effect was durable in long-term follow up.

Resting-state functional connectivity in major depression: abnormally increased contributions from subgenual cingulate cortex and thalamus

BACKGROUND

Positron emission tomography (PET) studies of major depression have revealed resting-state abnormalities in the prefrontal and cingulate cortices. Recently, fMRI has been adapted to examine connectivity within a specific resting-state neural network--the default-mode network--that includes medial prefrontal and anterior cingulate cortices. The goal of this study was to examine resting-state, default-mode network functional connectivity in subjects with major depression and in healthy controls.

METHODS

Twenty-eight subjects with major depression and 20 healthy controls underwent 5-min fMRI scans while resting quietly. Independent component analysis was used to isolate the default-mode network in each subject. Group maps of the default-mode network were compared. A within-group analysis was performed in the depressed group to explore effects of depression refractoriness on functional connectivity.

RESULTS

Resting-state subgenual cingulate and thalamic functional connectivity with the default-mode network were significantly greater in the depressed subjects. Within the depressed group, the length of the current depressive episode correlated positively with functional connectivity in the subgenual cingulate.

CONCLUSIONS

This is the first study to explore default-mode functional connectivity in major depression. The findings provide cross-modality confirmation of PET studies demonstrating increased thalamic and subgenual cingulate activity in major depression. Further, the within-subject connectivity analysis employed here brings these previously isolated regions of hypermetabolism into the context of a disordered neural network. The correlation between refractoriness and subgenual cingulate functional connectivity within the network suggests that a quantitative, resting-state fMRI measure could be used to guide therapy in individual subjects.

Case report: limbic system activation by intravenous lidocaine in a patient with a complex regional pain syndrome and major depression

Intravenous lidocaine is used to treat various neuropathic pain states. Systemic local anesthetics have been reported to cause behavioral alteration via limbic system activation. This case report describes a dramatic behavioral change in a patient receiving intravenous lidocaine and suggests a possible use of lidocaine to discriminate somatic and affective pain characteristics.

Psychoneuroendocrine immunology: perception of stress can alter body temperature and natural killer cell activity

Psychoimmunology has been credited with using the mind as a way to alter immunity. The problem with this concept is that many of the current psychoimmunology techniques in use are aimed at alleviating stress effects on the immune system rather than at direct augmentation of immunity by the brain. Studies in animals provide a model that permits us to approach the difficulties associated with gaining an understanding of the CNS-immune system connection. A particular advantage of using animals over humans is that psychological and social contributions play a less prominent role for animals than for human subjects, since the animals are all inbred and reared under identical controlled conditions. If the insightful information provided by animal studies is correct, then psychotherapy for the treatment of diseases might be made more effective if some aspect of this knowledge is included in the design of the treatment. We emphasize conditioning as a regimen and an acceptable way to train the brain to remember an output pathway to raise immunity. We propose that a specific drug or perception (mild stress, represented by rotation, total body heating or handling) could substitute and kindle the same output pathway without the need for conditioning. If this view is correct, then instead of using conditioning, it may be possible to use an antigen to activate desired immune cells, and substitute a drug or an external environmental sensory stimulus (perception) to energize the output pathway to these cells. Alternatively, monitoring alterations of body temperature in response to a drug or perception might allow us to follow how effectively the brain is performing in altering immunity. Studies with animals suggest that there are alternative ways to use the mind to raise natural or acquired immunity in man.

ECT in dissociative identity disorder and comorbid depression

Dissociative identity disorder (DID), previously named multiple personality disorder, is a diagnosis often complicated by comorbid major depression. We report on four cases of DID associated with severe self-destructive behavior and comorbid major depression treated with electroconvulsive therapy (ECT). In three of the patients, ECT appeared to be helpful in treating the comorbid depression without adversely affecting the DID. The potential risks of using ECT in patients with DID are reviewed.

The identity of the unconditioned stimulus to the central nervous system is interferon-beta

The specific mechanism of interaction between the central nervous system and immune system was examined using conditioned augmentation of natural killer (NK) cell activity. This study focused on the role of interferon-beta (IFN-beta) as the unconditioned stimulus (US). IFN-beta was found to be the signal responsible for the bidirectional communication which links the central nervous system with the immune system. This was substantiated by injection of small quantities of IFN-beta directly into the cisterna magna, which activated the effector pathway from the central nervous system to the immune system. More importantly, we found that when the conditioned stimulus (CS) was paired with an injection of IFN-beta into the cisterna magna, the conditioned animals were able to raise their natural killer cell activity in response to subsequent exposure to the conditioned stimulus. These studies show the unconditioned response must be the response of the central nervous system (CNS) to the unconditioned stimulus and not the direct effect of the substance injected into the periphery.

A simple, single, trial-learning paradigm for conditioned increase in natural killer cell activity

A change in natural killer (NK) cell activity can be conditioned with one trial learning when conditioned stimulus (CS) precedes the unconditioned stimulus (US). To avoid the problems associated with two reexposures in our earlier studies, we have developed a reliable and simple conditioning protocol utilizing the one trial learning and one reexposure to the odor CS. The conditioned change in NK cell activity was significantly different (P less than 0.05) from the control groups of mice. The paradigm is short and simple in that the conditioned change could be demonstrated within 3 days. We have also compared the effects of temporal association of CS and US on conditioned increase in NK cell activity. Forward conditioning (CS preceded the US) demonstrated a conditioned change, but the backward conditioning protocol did not. The paradigm provides a reliable approach to the study of mechanisms of the phenomenon of odor-NK conditioning.

A behavioral augmentation of natural immunity: odor specificity supports a Pavlovian conditioning model

BALB/c mice were conditioned by pairing an odor to an injection of poly-inosinic:poly-cytidylic acid (poly I:C), a strong inducer of natural killer (NK) cell activity as the unconditioned stimulus (US). When later reexposed to the odor conditioning stimulus (CS), these mice showed a conditioned augmentation of the NK cell response to a suboptimal dose of 1 microgram poly I:C. The two stimuli used in these studies were camphor (Ca) and citronella oil (Cr) odors, two chemically-related but distinct odor stimuli. The conditioned mice demonstrated the ability to discriminate between Ca and Cr, such that the conditioned response (CR) was only elicited by the odor CS used in the formation of the conditioned association. Exposure of conditioned mice to the non-associated odor stimulus on the test day did not elicit a change in the NK cell response to the suboptimal dose of poly I:C when compared to mice in the US group that had been given the US on day 0 without pairing to either odor stimulus. This specificity of the CR for the odor CS and not the unassociated odor stimulus supports the interpretation that the elevation of NK cell activity in this paradigm is due to Pavlovian conditioning and therefore dependent on central nervous system (CNS) associative processes.

Conditioning: a new approach to immunotherapy

It has been demonstrated by Parmiani et al. (Int. J. Cancer, 29: 323-332, 1982) that a significant protective effect can be obtained against the transplanted syngeneic YC8 lymphoma by prior immunization of BALB/c mice with normal allogeneic DBA/2 spleen cells. Using this well established tumor model, we investigated a novel approach, conditioning of specific immunotherapeutic activity. For this purpose, we used the odor of camphor as the conditioning stimulus and allogeneic DBA/2 spleen cells as unconditioning stimulus. We associated the conditioning and unconditioning stimuli two, three, and four times. Following this the conditioned animals were reexposed to the odor of camphor only. In each case, we observed a delay in tumor growth and in some instances the conditioned group performed better than the immunotherapy control group. These results indicate that a limited number of treatments with the antigen is better than the continuous treatment in maintaining the immunity and the homeostasis of the system.

Naltrexone blocks the expression of the conditioned elevation of natural killer cell activity in BALB/c mice

An elevation of natural killer (NK) cell activity was conditioned by the association of a camphor odor conditioning stimulus (CS) with an injection of 20 micrograms polyinosinic:poly-cytidylic acid (poly I:C), the unconditioned stimulus (US). Poly I:C elicits the production and secretion of interferon (IFN), which induces an increase in NK cell activity. Reexposure to the CS occurred on Days 3 and 5 after the association trial on Day 0. Immediately following the CS exposure on Day 5, 1 microgram poly I:C was administered to all animals. This procedure resulted in an increased NK cell activity in the conditioned (CND), but not the nonconditioned (NC), mice. In this study we have shown that the expression of the conditioned response was blocked by an injection of naltrexone (NTX) at 10 mg/kg ip when given immediately prior to the two test CS odor exposures. Peripheral treatment (ip) with a quaternary form of naltrexone (QNTX), which is a less potent opiate antagonist, at the same dose and at the same time relative to the CS odor reexposure did not block the conditioned response. The formation of the conditioned association did not appear to be disrupted by NTX at the 10 mg/kg dose when given immediately prior to the trial odor exposure on Day 0. No modulation of NK cell activity was observed in any of the control groups treated with naltrexone or the quaternary analog. Because of the inability of the QNTX to block the conditioned response, we hypothesize that the opiate receptors involved in the conditioned response and blocked by NTX were within the central nervous system (CNS). Whether this response is peripherally or centrally mediated, we have shown that opiate receptors represent part of the mechanism which mediates the conditioned augmentation of NK cell activity.

Conditioned augmentation of natural killer cell activity. Independence from nociceptive effects and dependence on interferon-beta

Injection of mice with 20 micrograms polyinosinic: polycytidylic acid (Poly I:C) after exposure to camphor odor results in a conditioned augmentation of natural killer cell (NK) activity. In this study, we show that the conditioned response is not the result of nociceptive stimulation and that interferon-beta (IFN), but not IFN-alpha can replace Poly I:C as the unconditioned stimulus (US). Two conditioned stimuli (CS) were used with equivalent results. A combination CS consisting of a novel taste (saccharin) and a 125 mg/kg injection of LiCl that induces gastric upset was paired with a Poly I:C or IFN-beta (1 X 10(4) IU) injection. This resulted in an augmentation of NK activity when the conditioned animals were reexposed to the saccharin-LiCl CS. In addition, an identical conditioned response was elicited when a camphor odor CS was paired with either of these US. To test whether the conditioned response might be an artifact not detected by our controls, a mock conditioning experiment was performed, which assessed the differential effect of multiple exposures to the saccharin-LiCl CS without a CS/US pairing. The mock conditioned group was significantly suppressed relative to saline treated controls, whereas the mock nonconditioned group and the mock conditioned group that was not reexposed to the CS after conditioning did not show significant suppression. This indicates that the augmentation observed in the conditioned group after CS/US pairing was not the result of exposure to the CS itself. Small doses of Poly I:C (5 micrograms or 2.5 micrograms) given on days 3 and 5 (or on day 5 only) to boost NK activity had the effect of increasing the magnitude of the conditioned response measured on day 6. In addition, an identical conditioned response was observed when the interval between the CS/US pairing and the later CS exposures was changed, which places the test for the conditioned response either on day 6 (CS given on days 3 and 5) or day 10 (CS given on days 7 and 9). These results show that the observed conditioned enhancement of NK activity in conditioned animals is not caused by any nociceptive properties of the CS itself and is dependent on the IFN-beta produced after Poly I:C injection in the conditioned paradigm.

Conditioned augmentation of natural killer cell activity. Independence from nociceptive effects and dependence on interferon-beta

Injection of mice with 20 micrograms polyinosinic: polycytidylic acid (Poly I:C) after exposure to camphor odor results in a conditioned augmentation of natural killer cell (NK) activity. In this study, we show that the conditioned response is not the result of nociceptive stimulation and that interferon-beta (IFN), but not IFN-alpha can replace Poly I:C as the unconditioned stimulus (US). Two conditioned stimuli (CS) were used with equivalent results. A combination CS consisting of a novel taste (saccharin) and a 125 mg/kg injection of LiCl that induces gastric upset was paired with a Poly I:C or IFN-beta (1 X 10(4) IU) injection. This resulted in an augmentation of NK activity when the conditioned animals were reexposed to the saccharin-LiCl CS. In addition, an identical conditioned response was elicited when a camphor odor CS was paired with either of these US. To test whether the conditioned response might be an artifact not detected by our controls, a mock conditioning experiment was performed, which assessed the differential effect of multiple exposures to the saccharin-LiCl CS without a CS/US pairing. The mock conditioned group was significantly suppressed relative to saline treated controls, whereas the mock nonconditioned group and the mock conditioned group that was not reexposed to the CS after conditioning did not show significant suppression. This indicates that the augmentation observed in the conditioned group after CS/US pairing was not the result of exposure to the CS itself. Small doses of Poly I:C (5 micrograms or 2.5 micrograms) given on days 3 and 5 (or on day 5 only) to boost NK activity had the effect of increasing the magnitude of the conditioned response measured on day 6. In addition, an identical conditioned response was observed when the interval between the CS/US pairing and the later CS exposures was changed, which places the test for the conditioned response either on day 6 (CS given on days 3 and 5) or day 10 (CS given on days 7 and 9). These results show that the observed conditioned enhancement of NK activity in conditioned animals is not caused by any nociceptive properties of the CS itself and is dependent on the IFN-beta produced after Poly I:C injection in the conditioned paradigm.

Regulation of natural immunity (NK activity) by conditioning

A paradigm is described for the conditioning of the NK response. Mice were exposed to a classical conditioning procedure in which saccharin and lithium chloride (LiCl) served as the conditioned stimulus (CS) paired with an injection of either poly I:C or cytoxan, the unconditioned stimulus (US). Poly I:C was used as the US for enhancement and cytoxan served as the US for suppression. Subsequent exposure to the CS either enhanced or suppressed the NK activity in the conditioned animals. Our studies showed that only one association was needed for the learning to take place, training to consumption of water was not necessary, and the conditioned (enhanced) response could be recalled as soon as 7 days after pairing of the US and CS.

Conditioned enhancement of natural killer cell activity, but not interferon, with camphor or saccharin-LiCl conditioned stimulus

Pavlovian conditioning of the natural killer (NK) cell response has been demonstrated by pairing camphor with polyinosinic:polycytidylic acid (poly I:C) in nine association trials. The NK cell response could be conditioned also by using combined saccharin and lithium chloride (LiCl) as the conditioned stimulus. The camphor and saccharin-LiCl paradigms were tested to determine if the conditioned NK cell activity was the result of conditioning of the interferon response. Interferon levels were measured at 6 hr and NK cell activity at 24 hr after application of the conditioned stimulus. The interferon levels measured in separate experiments were not uniformly elevated in conditioned animals compared with controls.

Neural and environmental influences on neoplasia and conditioning of NK activity

The effects of physical restraint and poly I:C treatment on the growth of MOPC 104E myeloma and murine osteosarcoma and survival of animals bearing such tumors were investigated. Our studies show that in the Balb/c mice with MOPC 104E myeloma the effects of restraint stress were detrimental and lead to early death of the mice. When the restraint was combined with poly I:C, during the early course of the disease, restraint stress neutralized the beneficial effects of the poly I:C treatment. These studies show that under certain circumstances, restraint stress can negate the effects of therapy. On the other hand, restraint stress produced an opposite effect in C3H/He mice with murine osteosarcoma tumor treated in the same fashion. In mice with osteosarcoma, restraint stress delayed tumor growth and increased the median survival time. When restraint stress was combined with poly I:C treatment, the mean tumor size was smaller and median survival was substantially increased over the control group. Because poly I:C therapy delayed tumor growth and increased survival in both models, efforts to strengthen this response were tested by conditioning. Our studies show the response to poly I:C as measured by elevation of the NK activity could be conditioned with camphor smell. Conditioning of the host to raise immune activity to alter the outcome of disease is a new area yet to be explored and has important clinical significance. These studies, we believe, are important because they explore the connection between mind and body and resistance to disease.