A New Viewpoint on the Etiopathogenesis of Depression: Insights From the Neurophysiology of Deep Brain Stimulation in Parkinson's Disease and Treatment-Resistant Depression

The Efficacy of Transcranial Magnetic Stimulation in the Treatment of Obsessive-Compulsive Disorder: An Umbrella Review of Meta-Analyses

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) has been increasingly used for treating obsessive-compulsive disorder (OCD). Although several meta-analyses have explored its effectiveness and safety, there is no umbrella review specifically focused on rTMS for OCD. This umbrella review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and analyzed relevant meta-analyses on rTMS for OCD.

METHODS

Twenty-three articles were identified from PubMed, and after screening, 12 meta-analyses were included in the review. The studies analyzed in the meta-analyses ranged from 10 to 27, with total participants ranging from 282 to 791. The most commonly studied regions were the dorsolateral prefrontal cortex (DLPFC), supplementary motor area (SMA), and orbito-frontal cortex (OFC).

RESULT

The majority of the meta-analyses consistently supported the effectiveness of rTMS in reducing OCD symptoms when applied to the DLPFC and SMA. Encouraging results were also observed when targeting the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC) through deep transcranial magnetic stimulation (dTMS). However, there was a high level of heterogeneity in the findings of nine out of 12 meta-analyses.

CONCLUSION

In conclusion, existing evidence suggests that rTMS targeting the DLPFC and SMA consistently reduces OCD symptoms, but targeting the mPFC and ACC through dTMS shows variable results. However, the high heterogeneity in the study findings indicates a need for further research and standardization in the field.

Neuroplasticity: The Continuum of Change

Neuroplasticity is a term that is increasingly permeating mainstream discourse and being used by the popular press to simplify descriptions of how the brain changes in response to stimuli such as exercise, sleep, food, drugs of abuse, and medicines, among others. However, it is a complex, multifaceted concept representing a continuum connecting molecular, cellular, and circuit-level changes and their effects on human behavior. In this Viewpoint, we examine neuroplasticity from several perspectives to construct a holistic view of this ambiguous term. By engaging experts across various scientific disciplines, we attempt to provide an easy entry point to the concept of neuroplasticity for readers of ACS Chemical Neuroscience. By highlighting how neuroplasticity changes in both health and disease, we demonstrate that the concept is applicable to both adaptive and maladaptive responses to stimuli, underscoring its significance in chemical neuroscience.

Psychotic Symptoms Associated With a Frontoparietal Arachnoid Cyst: The Role of Neuroimaging Studies in First-Episode Psychosis

Arachnoid cysts, although usually asymptomatic, can be associated with psychiatric symptoms, including delusions and hallucinations. The role of neuroimaging findings, particularly arachnoid cysts, and their influence on psychiatric symptoms is still controversial and debated. We present the case of a 56-year-old male who sought medical help for his psychotic symptoms, mainly paranoid delusions, and auditory and tactile hallucinations. Brain imaging studies at the time of admission revealed a large left frontoparietal arachnoid cyst. The patient was then started on psychiatric medication but did not show any sign of clinical improvement. After discussing the case with the patient´s neurosurgeon, it was decided to submit the patient to drainage of his arachnoid cyst. The patient was reevaluated two weeks after the procedure showing significant clinical improvement, particularly in his positive psychotic symptoms. The rapid improvement of the psychotic symptoms after removing the cyst suggests that, at least in part, the mass was contributing to the symptoms presented.

Molecular basis and clinical perspectives of deep brain stimulation for major depressive disorder

It is possible to consider the stimulation of the cingulate gyrus in its portion below the corpus callosum (SCC, or subcallosal cingulate cortex) as an effective, promising, and safe alternative intervention for treatment-resistant depression. In studies with deep brain stimulation - DBS, when follow-on with functional magnetic resonance imaging and/or PET-CT (Positron emission tomography-computed tomography) is performed, it is observed an increase in the blood supply and glucose metabolism in this region, which is the anterior part of the limbic system. This same location has good experimental results also for the treatment of anorexia nervosa. The hypotheses suggest a greater activation of the reward system, a greater sense of well-being, and a consequent reduction in depressive symptoms, the objective of the treatment. Over the last 20 years, multicenter studies have shown symptomatic improvement in 50-60% of patients, and about a third even reach criteria for remission of the depressive disorder.

Noninvasive Delivery of Biologicals to the Brain

In the past, psychotherapy and neuropharmacological approaches have been the most common treatments for disordered thoughts, moods, and behaviors. One new path of brain therapeutics is in the deployment of noninvasive approaches designed to reprogram brain function at the cellular level. Treatment at the cellular level may be considered for a wide array of disorders, ranging from mood disorders to neurodegenerative disorders. Brain-targeted biological therapy may provide minimally invasive and accurate delivery of treatment. The present article discusses the hurdles and advances that characterize the pathway to this goal.