MINI REVIEW article

Front. Neurosci., 15 February 2019

Sec. Neuroprosthetics

Volume 13 - 2019 | https://doi.org/10.3389/fnins.2019.00108

Evolution in the Treatment of Psychiatric Disorders: From Psychosurgery to Psychopharmacology to Neuromodulation

  • 1. Department of Neurosurgery, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH, United States

  • 2. Department of Clinical Neurological Sciences, London Health Sciences Centre, Western University, London, ON, Canada

  • 3. Department of Psychiatry, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH, United States

Abstract

The treatment of psychiatric patients presents significant challenges to the clinical community, and a multidisciplinary approach to diagnosis and management is essential to facilitate optimal care. In particular, the neurosurgical treatment of psychiatric disorders, or “psychosurgery,” has held fascination throughout human history as a potential method of influencing behavior and consciousness. Early evidence of such procedures can be traced to prehistory, and interest flourished in the nineteenth and early twentieth century with greater insight into cerebral functional and anatomic localization. However, any discussion of psychosurgery invariably invokes controversy, as the widespread and indiscriminate use of the transorbital lobotomy in the mid-twentieth century resulted in profound ethical ramifications that persist to this day. The concurrent development of effective psychopharmacological treatments virtually eliminated the need and desire for psychosurgical procedures, and accordingly the research and practice of psychosurgery was dormant, but not forgotten. There has been a recent resurgence of interest for non-ablative therapies, due in part to modern advances in functional and structural neuroimaging and neuromodulation technology. In particular, deep brain stimulation is a promising treatment paradigm with the potential to modulate abnormal pathways and networks implicated in psychiatric disease states. Although there is enthusiasm regarding these recent advancements, it is important to reflect on the scientific, social, and ethical considerations of this controversial field.

Introduction

The management of psychiatric disorders is challenging and often requires a multimodal approach to diagnosis and treatment. There is a rich history of innovation in the field, driven by scientists, physicians and surgeons. In particular, the neurosurgical treatment of psychiatric disorders has a long and tumultuous history fraught with controversy. However, the legacy of “psychosurgery” has also given rise to the development of modern standards for research and ethics, and has fostered a deeper understanding of the pathophysiology of human behavior. Although there is evidence of psychosurgery spanning multiple thousands of years throughout human history, the most exciting, but also provocative developments have been within the past century, attributable to the combined efforts of scientists and physicians. In the 1950s, ablative surgery fell out of favor due to the rise of effective pharmacology and intense professional and public criticism, although research and practice continued with more rigorous standards. Although the modern treatment of psychiatric disorders is primarily medical, the high incidence of treatment resistance and failure has fostered a renewed interest in surgical treatments with a non-ablative focus.

The aim of this article is to provide a brief chronological overview of the treatment of psychiatric diseases from ablation to pharmacology to neuromodulation. Despite a history of controversy, interest in the potential of surgery for psychiatric disorders has endured and even increased within the past few decades, primarily driven by the proliferation and success of neuromodulation and by improvements in structural and functional neuroimaging. It is important to view developments in psychosurgery in the context of the historical and current understanding of the neurobiology and pathophysiology of consciousness and behavior, the available treatments for psychiatric disorders, and the adherence to (or lack thereof) research ethics.

A Historical Perspective

The Origins of Psychosurgery

The earliest evidence of presumed psychosurgery has its origins in the Neolithic era; several skulls from this period have been identified with areas of trephination and evidence of healing (; ), suggesting that these early procedures were likely performed with therapeutic intent. Although concurrent fractures have been identified in some specimens, numerous other skulls bear no obvious signs of trauma (). It has been hypothesized that early trephination was performed for ritualistic or spiritual purposes, with the intent to treat manifestations of headaches, epilepsy, and mental illness (). During the classical era, detailed guidelines regarding trephination, primarily for trauma, were outlined in the Hippocratic text “peri ton en cephali traumaton,” translated to “On Head Wounds” or “On Injuries of the Head” (). Psychosurgery was also depicted in the medical literature and artwork of the Renaissance era, notably in “The cure of folly or the operation for the stone,” a painting by Hieronymus Bosch referring to the belief that madness was caused by a physical stone within the brain ().

The practice of psychosurgery was then largely absent from Western medicine for a few hundred years until its resurgence in the modern era. Throughout the 1800s, new insights into functional neuroanatomy and neurophysiology laid the foundation for renewed interest. In 1819, Franz Joseph Gall published his treatise on phrenology, which suggested that the brain possessed discrete functional regions (). Although phrenology was flawed and ultimately discredited, the idea of neurological functions having an anatomical correlate was expanded on by seminal work on the localization of language from Paul Broca and Carl Wernicke, and further work by Gustav Fritsch, Eduard Hitzig, and David Ferrier on localization of the motor cortex (). The study of patients with traumatic brain injuries was also essential, the most famous example being Phineas Gage, who sustained a penetrating injury to his dominant frontal lobe and subsequently developed aggressive and impulsive behavior ().

The Advent of Modern Psychosurgery

Inspired by these findings, Swiss psychiatrist Gottlieb Burckhardt performed the first psychosurgical treatments in 1888. These procedures, conducted on six patients with mental illnesses, consisted of topectomies to excise brain regions, thought to be responsible for aggression, agitation or hallucinations (); Burckhardt was subsequently ostracized from the medical community. The research and practice of psychosurgery again entered into dormancy and was largely quiescent until 1935, when John Fulton and Carlyle Jacobsen described the role of the frontal lobe in short term memory, anxiety and aggression in a primate model (). In attendance of this lecture was Egas Moniz, a Portuguese neurologist who, together with the neurosurgeon Almeida Lima, developed the prefrontal leucotomy procedure for the treatment of psychiatric patients with prominent depression, anxiety or aggression (). This procedure initially consisted of alcohol injections into the prefrontal white matter, and Moniz eventually developed the leucotome, an instrument that could be introduced through frontal burr holes for precision lesioning ().

The Prefrontal Lobotomy and Enduring Controversy

This work of Moniz and Lima inspired the Americans Walther Freeman, a neurologist, and James Watts, a neurosurgeon, who further refined the prefrontal leucotomy technique to allow for larger lesions that presumably disrupted widespread brain networks associated with affective processing. The precision leucotome was subsequently developed, and procedural modifications were introduced to allow for more accurate lesion localization using anatomical landmarks (). This refined procedure was named the prefrontal lobotomy: minimal lobotomies were predominantly performed for the treatment of affective symptomatology, whereas radical lobotomies were for schizophrenic patients or those with refractory symptoms (). Freeman and Watts performed hundreds of procedures, and described relative success in the treatment of depression, agitation and aggression, although they cautioned its use should be limited to those patients with severe and refractory symptoms (). Unfortunately, this led to indiscriminate use of the lobotomy, partially in response to the lack of conventional treatments for mental illness, and also as a potential measure of reducing asylum overcrowding ().

Freeman became emboldened by his initial success, and co-opted a transorbital technique developed by the Italian psychiatrist Amarro Fiamberti. This involved the insertion an instrument resembling an ice-pick, the orbitoclast, through the orbit into frontal lobe white matter, which allowed for lesioning via a sweeping motion in the coronal plane (). This technique was much quicker than the standard lobotomy and only required electroshock therapy for sedation; as a result, Freeman did not require an anesthetist, surgeon, or even proper sterile technique. In response, Watts and the neurosurgical community distanced themselves from this practice, and Freeman went on to perform thousands of procedures across America (). The transorbital lobotomy was widely and eagerly adopted throughout America and parts of Europe, with tens of thousands of procedures performed across nearly two decades (). To illustrate the sheer popularity within the scientific community for psychosurgery at the time, the 1949 Nobel Prize in medicine or physiology was awarded in-part to Moniz for the leucotomy ().

Stereotactic Neurosurgery and the Advent of “Minimalism”

Eventually, both professional and public opinion turned against the lobotomy as the associated morbidity and mortality became more apparent (). A number of patients also developed a “post-leucotomy syndrome,” characterized by apathy, emotional blunting, and disinhibition. For these reasons, the medical community sought more scientifically rigorous surgical approaches focused on hypothesis-driven targeting with less aggressive lesioning and resections. The neurosurgeon William Scoville was an early proponent of these principles and performed selective undercutting of the orbitofrontal cortex (). Further improvements were realized with advancements in stereotactic neurosurgery, which superseded open and closed lesioning techniques.

The earliest stereotactic apparatus had previously been developed by Sir Victor Horsley and Robert Clark for animal experimentation (), and its clinical translation was described by Ernest Spiegel and Henry Wycis (). Using x-ray ventriculography, the dorsomedial nucleus of the thalamus was targeted to treat agitation and psychosis (). Further advances in psychosurgical stereotaxis led to the development of the stereotactic cingulotomy, capsulotomy, subcaudate tractotomy, and limbic leucotomy; rather than removing the entire frontal lobe to produce symptom relief, targeted lesions of white matter pathways and gray matter structures were found to be comparable in effect with fewer side effects (). These procedures continue to be used for refractory psychiatric illness in contemporary practice. Additional targets, including the amygdala and hypothalamus, have also been described but are less commonly used.

The cingulotomy has been used for a variety of disorders, and involves lesioning of the cingulate gyrus and adjacent white matter fibers of cingulum bundle. In 1952, Sir Hugh Cairns described this technique for symptoms of anxiety and obsession (). The cingulotomy has since been used in the treatment of obsessive-compulsive disorder (OCD), treatment-resistant depression (TRD), and was similarly found to be effective for individuals suffering from chronic, intractable pain (). The cingulotomy remains the most commonly performed psychosurgical procedure in North America (), and its therapeutic effects are in-part believed to involve disruption of cortico-striato-thalamo-cortical circuitry.

Anterior capsulotomy has also been found to be effective for OCD, likely due to the disruption of frontothalamic fiber connections. It can be performed with radiofrequency coagulation, as originally described by Jean Talairach, or via gamma knife radiosurgery as described by Lars Leksell (). Subcaudate tractotomy disrupts the orbitofrontal cortex from its thalamic and limbic connections, and its early use can be traced to Scoville’s orbitofrontal corticectomy (). Its adaptation into a stereotactic procedure can be attributed to Geoffrey Knight (), and was initially performed via bilateral insertion of yttrium rods to cause radiation necrosis before transitioning to radiofrequency coagulation (). Subcaudate tractotomy has been described for TRD and OCD, although cingulotomy and capsulotomy have largely surpassed its use in contemporary medicine (). Lastly, the limbic leucotomy combines cingulotomy with tractotomy to target both frontothalamic and cingulate circuitry. First described by Desmond Kelly and Alan Richardson in 1973 (), it is likewise used for TRD and OCD. Ultimately, these techniques share a common theme of wide-spread neural network disruption.

The Fall of Psychosurgery and the Rise of Pharmacology

The decline of psychosurgery in the 1950s can be attributed to numerous factors. The initial enthusiasm for frontal lobotomies was driven by widespread social acceptance and Freeman’s deft hand for advocacy and marketing. However, this also resulted in a laissez-faire attitude toward psychosurgery, with procedures being performed by non-neurosurgeons in inappropriate settings. This triggered professional criticism regarding the significant and largely underreported adverse events (), and the lack of objectivity and scientific rigor. Furthermore, the public became aware of the undesirable consequences of lobotomies. Social attitudes were shaped by negative depictions in literature and film, including notable examples such as One Flew Over the Cuckoo’s Nest. It also became apparent that some institutionalized or incapacitated patients were lobotomized without informed consent, and procedures may have been performed on prisoners to address dysfunctional behavior as opposed to mental illness (). The controversy surrounding psychosurgery was instrumental in developing modern standards for research and ethics, with the passing of the National Research Act of 1974 and subsequent publication of the Belmont Report, which outlined the principles of informed consent and guidelines regarding the performance of medical procedures and research.

However, it was the evolution of pharmacotherapy that finally turned the tide against psychosurgery, particularly with the advent of lithium () and chlorpromazine () therapy. In particular, the use of chlorpromazine in the early 1950s provided an effective non-surgical treatment for severe aggression and psychosis. As a result, psychosurgery fell out of favor and psychopharmacology thrived as brisk sales prompted investment and further innovation. The development and approval for other antipsychotic and antidepressant agents soon followed, with evidence that medical therapy was more effective, safer, and cheaper than psychosurgery.

Modern Psychopharmacological Treatments and Limitations to Medications

The standard first-line treatments for psychiatric disorders include medications and psychotherapy. Commonly used pharmacological agents are outlined in Table 1 (; ; ; ; ). Interestingly, there is significant overlap among psychiatric disorders and the pharmacological agents used in treatment, suggesting that these disorders likely involve widespread and shared circuitry and/or neurotransmitters.

Table 1

ConditionClassMedicationsIndicationSymptoms targetedContraindications and/or Precautions∗Side effects
Major Depressive DisorderSSRICitalopram
Escitalopram
Fluoxetine
Paroxetine
Sertraline
First lineAttention, anxiety, depression, energyProlonged QT interval (primarily citalopram and escitalopram)Anxiety, increased bleeding, diarrhea, dry mouth, headache, hyponatremia, insomnia, orthostasis, QTc prolongation, sedation, sexual dysfunction, weight gain
SNRIDesvenlafaxine
Duloxetine
Venlafaxine
Levomilnacipran
First lineAttention, anxiety, depression, energyHepatic or renal impairment, narrow angle glaucomaHeadache, hypertension, insomnia, orthostasis, nausea, vomiting
NDRIBupropionFirst lineAppetite, depression, energyAnorexia, alcohol or sedative withdrawal, Bulimia, EpilepsyAnxiety, dry mouth, insomnia, seizures, weight loss
NaSSAMirtazapineFirst lineAppetite, anxiety, depression, sleepConstipation, sedation, weight gain, aplastic anemia (rare)
SMNefazodone
Trazodone
Second lineAnxiety, depression, sleepHepatic impairmentLiver toxicity, priapism, orthostasis, sedation
TCAAmitriptyline
Imipramine
Nortriptyline
Desipramine
Doxepin
Trimipramine
Second lineAnxiety, depression, energy, sedationAcute recovery from myocardial infarctionCardiac conduction effects, diaphoresis, dizziness, orthostasis, sedation, seizures, tremor, weight gain
MAOIPhenelzine
Tranylcypromine
Thirdor fourth lineAnxiety, depression, energyCongestive heart failure, pheochromocytoma, hepatic or renal impairmentConstipation, dry mouth, hypertensive crisis, insomnia, orthostasis, sedation, sexual dysfunction, weight gain
Bipolar DisorderATAAripiprazole
Lurasidone
Olanzapine
Quetiapine
Risperidone
Ziprasidone
Asenapine
Clozapine
Paliperidone
Acute or maintenance phaseDepression, mania, mood stabilizationProlonged QT interval, recent myocardial infarction, heart failure, Parkinson diseaseAgranulocytosis, akathisia, cataracts, cardiomyopathy, constipation, dystonia, hyperlipidemia, hyperprolactinemia, orthostasis, parkinsonism, sedation, seizures, sexual dysfunction, tardive dyskinesia, weight gain
SSRIFluoxetineAcute phase if combined with OlanzapineDepression(see above)(see above)
MetalLithiumAcute or maintenance phaseDepression, mania, mood stabilization, suicidalitySevere cardiac or renal impairment, severe dehydration/low sodiumAlopecia, confusion, diabetes insipidus, diarrhea, fatigue, hypocalcemia, hypothyroidism, nausea, t-wave changes, tremor, weakness, weight gain
ACValproate, Carbamazepine LamotrigineAcute or maintenance phaseDepression, mania, mood stabilizationAV heart block, blood dyscrasia, hepatic impairment, hepatic porphyriaAlopecia, anemia, anorexia, diarrhea, hepatotoxicity, hyponatremia, nausea, sedation, Stevens-Johnson syndrome, thrombocytopenia, tremor, vomiting, weight gain
OtherThyroid
hormone
Third line or augmentationDepressionTremor, headache, nausea, weight loss
DAPramipexoleAcute phaseDepressionSevere cardiac or renal impairmentDyskinesia, orthostasis, nausea
DRIModafinil
Armodafinil
Acute phaseDepressionSevere anxietyDecreased appetite, headache
Obsessive Compulsive DisorderSSRIFluoxetine
Fluvoxamine
Paroxetine
Sertraline
First lineObsessions, compulsions(see above)(see above)
TCAClomipramineSecond lineObsessions, compulsions(see above)(see above)
ATAOlanzapine
Risperidone
Second line if combined with SSRIObsessions, compulsions(see above)(see above)
TAHaloperidolSecond line if combined with SSRIObsessions, compulsionsLong QT interval, narrow angle glaucoma, Parkinson diseaseAkathisia, dystonia, parkinsonism, sedation, tardive dyskinesia, sexual dysfunction
Tourette SyndromeA2AClonidine
Guanfacine
First lineTics, hyperactivityCardiac insufficiencyDizziness, dry mouth, headache, irritability, orthostasis, sedation
ACTopiramateFirst lineTicsRecent alcohol useAtaxia, confusion, diplopia, fatigue, sedation, weight loss
TAHaloperidol
Pimozide
Second lineTics(see above)Akathisia, constipation, dystonia, parkinsonism, sedation, tardive dyskinesia, sexual dysfunction, xerostomia
ATAAripiprazoleSecond lineTics(see above)(see above)
MAUITetrabenazineThird lineTicsDepression, parkinsonism, suicidalityAnxiety, depression, hypotension, insomnia, nausea, sedation

Summary of modern psychopharmacological agents.

∗specific drug interactions not listed. SSRI, selective serotonin reuptake inhibitor; SNRI, serotonin norepinephrine reuptake inhibitor; NDRI, norepinephrine dopamine reuptake inhibitor; NaSSA, noradrenergic and specific serotonergic antidepressant; SM, serotonin modulator; TCA, tricyclic antidepressant; MAOI, monoamine oxidase inhibitor; ATA, atypical antipsychotic; AC, anticonvulsant; DA, dopamine agoinst; DRI, dopamine reuptake inhibitor; TA, typical antipsychotic; A2A, alpha II adrenergic agonist; MAUI, monoamine uptake inhibitor.

However, treatment resistance or failure is common, necessitating alternative strategies. The first strategy is commonly to optimize medication dosing or scheduling, or switching to another therapeutic class. TRD, for example, refers to an inadequate response to at least one antidepressant trial, and can occur in up to half of patients (). Even with optimized multi-modal therapy, up to 30% of patients with major depression are non-responders (). Similarly, a significant proportion of patients with OCD (), bipolar disorder (), and malignant Tourette syndrome () fail to respond to standard therapy, again suggesting that the underlying pathophysiology is likely complex and involves multiple networks. These treatment-resistant patients often have more severe symptoms, and higher rates of morbidity and mortality. As such, new therapeutic strategies are desperately required.

Other Neuromodulation Therapies

Like psychosurgery, electroconvulsive therapy (ECT) was introduced before the advent of psychopharmacology. Despite its documented efficacy in the treatment of psychiatric disorders, its side effects on cognition and memory and misuse/abuse by some practitioners dramatically decreased its use before the 1980s. The realization of the imperfect effects of psychotropics “resuscitated” the use of ECT, although it is still considered under-utilized, primarily due to misconceptions regarding treatment (). Although the exact mechanism is not understood, the induction of a generalized seizure and subsequent post-ictal suppression is effective for TRD () and bipolar disorder (), and may also be beneficial for OCD ().

Additional non-invasive therapies include magnetic seizure therapy, which focally induces the superficial cortex to produce seizures, repetitive transcranial magnetic stimulation, involving the pulse application of magnetic stimuli to alter cortical excitability, and vagal nerve stimulation, which sends electrical impulses to various brain regions via the solitary nucleus (). The role for these alternative treatments remains unclear, as ECT is generally considered clinically superior (; ). However, the remission rates for TRD with ECT are reportedly from 35 to 53% (). Clearly, a significant number of patients will not respond to pharmacological and non-invasive neuromodulation treatments, suggesting that more invasive surgical interventions like deep brain stimulation (DBS) can be considered as a viable option for patients with psychiatric disorders who fail “all” available treatments.

Necessity of Neuromodulation

With the advent of DBS, a reversible and adaptable technology, the use of lesioning procedures has lessened to some degree. Moreover, DBS has the potential to modulate numerous widespread networks. The most effective application of DBS has historically been in the treatment of movement disorders, however, its use has been trialed in a number of psychiatric conditions including Tourette syndrome (; ; ; ; ; ; ; ), OCD (; ; ; ; ; ), and depression (; ; ; ; ; ; ; ; ). Yet, OCD is the only psychiatric disorder for which DBS is currently FDA-approved under a humanitarian device exemption. A summary of relevant clinical trials, including their outcomes and adverse events is listed in Table 2.

Table 2

Psychiatric DisorderDBS targetAuthors and YearNumber of PatientsOutcomesTherapy-Related adverse events∗
Tourette SyndromeThalamus1Complete abolition of ticsNone reported
544% mean reduction in YGTSSAcute psychotic episode
649% mean reduction in YGTSSGaze disturbances, reduced energy
5Improvements in YGTSS, but did not meet main outcome measure of 50% improvementNone reported
GPi165% mean reduction in YGTSSWeight loss (attributed to neuroleptic withdrawal)
1515.3% mean reduction in YGTSSHypomanic episode
NAcc141% mean reduction in YGTSS (NAcc+VC/VS)None reported
186% mean reduction in YGTSSNone reported
Obsessive Compulsive DisorderVC/VS4Beneficial effects in 75% of patientsNone reported
26≥ 25% reduction in YBOCS in 73% of patientsHypomanic episode, irritability, suicidal ideation
NAcc1625% mean reduction in YBOCS compared to shamForgetfulness, word finding difficulties
10≥ 25% mean reduction in YBOCS in 50% of patientsDysesthesia, headache, hypomanic episode, suicidal ideations
STN832% mean reduction in YBOCS compared to shamAmbulatory difficulty, hypomanic episode, dyskinesia, dysphagia
ITP551% mean reduction in YBOCSConfusion, dysautonomia
DepressionNAcc1145% sustained response after 4 yearsSuicide (non-responder)
SCC2064% response rate after 3–6 yearsSuicide
5Reduction of HDRS during active stimulation compared to sham in 80% of patientsNone reported
2129% reduction in HDRSNausea, vomiting, suicide
1792% response and 58% remission after 2 yearsTwo suicide attempts (stress association)
11Preoperative deterministic tractography matched with postoperative probabilistic tractography; 82% response and 55% remission after 1 yearNone reported
VC/VS1553% response and 40% remission at last follow-upHypomanic episode, syncope, disinhibition
2540% response, 24% partial response and 20% remission after optimization phaseSuicidal ideation and attempts, nocturia, blurred vision, disinhibition
MFB786% response and 57% remission after 12–33 weeksDizziness, oculomotor disturbances, increasing sweating

Deep brain stimulation for psychiatric disorders: selected references.

∗not including device or implantation-related complications. GPi, globus pallidus internus; HDRS, Hamilton Rating Scale for Depression; ITP, Inferior thalamic peduncle; MFB, medial forebrain bundle; NAcc, nucleus accumbens; SCC, subcallosal cingulate cortex; STN, subthalamic nucleus; VC/VS, anterior limb of the internal capsule/ventral capsule/ventral striatum; YBOCS, Yale-Brown Obsessive Compulsive Scale; YGTSS, Yale Global Tic Severity Scale.

Although DBS has shown efficacy in patients with treatment-resistant major depression and bipolar depression (), the investigation of DBS for such diseases at TRD in larger scale randomized trials has been less successful (; ). This may in part be due to the unclear determination of targets that would effectively produce the same results seen with lesioning techniques. Traditionally, DBS targets have been selected based on neuroimaging findings and historical results of lesioning procedures, though clearly further hypothesis-directed targeting studies are needed.

Future Directions

There are numerous limitations to the current understanding and treatment of psychiatric disorders. These are complex disease states which cannot be localized to distinct anatomical correlates, and are influenced by cognitive, behavioral and emotional factors. As such, the contemporary understanding of psychiatric disease may be attributable to a dysfunction of networks rather than an isolated structural or neurotransmitter abnormality. This interpretation can be traced to seminal works including the description of the Papez and cortico-striato-thalamocortical circuits, which postulate that functional subdivisions influence various facets of behavior (; ).

If these diseases are truly abnormalities in wide-spread white matter connections and brain circuitry, then a better understanding of such pathways in the human brain is essential. While data from animal studies remains the gold-standard for the evaluation of white matter fiber tracts, these models may not accurately translate to the human correlate with such complex behavioral and cognitive processing. Moreover, although improvements in neuroimaging have been fundamental in advancing our understanding of the underlying neurobiology and circuitry involved in psychiatric disorders, these also have limitations in their ability to precisely and accurately allow the visualization of these connections. Innovations in neuro-imaging techniques will be necessary to help identify radiographic biomarkers indicative of a particular disease entity. Methodological innovations that may improve the accuracy of imaging technologies include advances in machine learning, optimization of signal prediction error, and the development of novel imaging algorithms (). Furthermore, there is likely significant patient variability regarding this underlying circuitry. Riva-Posse et al. have previously demonstrated that patient responders to DBS for TRD shared similar fiber pathways that were being stimulated (). Their subsequent prospective study utilizing probabilistic tractography resulted in a high patient response rate, suggesting an important role for targeting based on patient-specific data ().

Advances in DBS technology and transition to a “closed loop” system may hold promise for the treatment of psychiatric disorders based on patient or disease-specific biomarkers. Conventional “open loop” stimulation requires the physician to adjust stimulation parameters based on subjective evaluations, whereas a closed-loop system adjusts stimulation parameters based on direct measurement of a neural biomarker (). In Parkinson’s disease, pathological beta band activity may represent an essential biomarker for adaptive stimulation (). However, biomarker identification in psychiatric disease states will prove to be more challenging due to clinical heterogeneity, and may be dependent on identifying commonalities among disease phenotypes (). The implantation of DBS electrodes allows for both acute (microelectrode) and chronic (macroelectrode) recordings to identify potential electrophysiological biomarkers in psychiatric disease states. Such recordings may provide insight into the electrophysiological correlates of acute symptomatology, and also long-term changes as a result of the disease process or chronic DBS therapy.

There is emerging evidence that local field potential activity from various brain regions may have distinct patterns in psychiatric disorders (; ), and that invasive electrophysiology may allow for circuitry identification and modulation in selected patients (). In a pre-clinical study of mice prone to binge-eating, Wu et al. observed that closed-loop stimulation of the nucleus accumbens disrupted rewarding behavior (). Specifically, the identified biomarker was pathological delta band activity from local field potential recordings. Although promising, closed-loop stimulation has yet to be clinically validated in psychiatric disorders.

It has also been suggested that the lack of treatment success of DBS for psychiatric disorders in larger clinical studies may be attributable to the clinical trial design itself (). Whereas the efficacy of DBS for movement disorders can be reliably measured based on objective markers, the diagnostic criteria and interpretation of psychiatric disorders can be more variable and complex, and the clinical response may take longer to manifest. As such, clinical trial design should take into consideration different therapeutic endpoints and/or a longer trial period.

Ultimately, the contemporary use of neuromodulation for mental illness will need to focus on a hypothesis-driven approach to target selection and will likely incorporate multiple targeting methods using novel technologies to produce effective results (, ). Patient heterogeneity should not be under-valued, and an individualized approach may also be required, be it symptom-directed, patient-directed, or both ().

Conclusion

The modern resurgence of surgical therapies for psychiatric disorders must respect the lessons learned from the early and mid-twentieth century, particularly the ethical and social ramifications of poor scientific rigor. The treatment of psychiatric patients continues to be challenging, especially in those patients deemed incapable of making informed decisions. For these reasons, the practice of psychosurgery should embrace a multidisciplinary approach to diagnosis and management. The future of psychiatric treatments will undoubtedly involve concurrent developments in the fields of behavioral neuroscience, neuroimaging, psychopharmacology, and neurosurgery.

Statements

Author contributions

MS and JS participated in manuscript conceptualization, design, and preparation. MS, EH, KG, JM, and JS provided critical revisions of the manuscript and reviewed the submitted version. KG, JM, and JS provided administrative support.

Funding

This work was supported by the National Institutes of Health Grant 2KL2TR000440.

Conflict of interest

JS receives grant support from the National Institutes of Health (2KL2TR000440; clinicaltrials.gov, NCT02655978) and is on the Scientific Advisory Board for Koh Young Inc. KG was on a speakers bureau of AstraZeneca, Pfizer and Sunovion, and an Advisory Board of Sunovion and Otsuka, and received grant supports from AstraZeneca, Brain and Behavior Research Foundation, and Cleveland Foundation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

Summary

Keywords

psychosurgery, lobotomy, psychiatric disease, depression, obsessive-compulsive disorder, Tourette syndrome, brain circuitry, deep brain stimulation

Citation

Staudt MD, Herring EZ, Gao K, Miller JP and Sweet JA (2019) Evolution in the Treatment of Psychiatric Disorders: From Psychosurgery to Psychopharmacology to Neuromodulation. Front. Neurosci. 13:108. doi: 10.3389/fnins.2019.00108

Received

28 March 2018

Accepted

29 January 2019

Published

15 February 2019

Volume

13 - 2019

Edited by

Peter Brunner, Albany Medical College, United States

Reviewed by

Ali Yadollahpour, Ahvaz Jundishapur University of Medical Sciences, Iran; Erika Kristine Ross, Mayo Clinic, United States; Nataly Raviv, Albany Medical College, United States

Updates

Copyright

*Correspondence: Jennifer A. Sweet,

This article was submitted to Neuroprosthetics, a section of the journal Frontiers in Neuroscience

Disclaimer

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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