Paul E. Croarkin

Psychomotor retardation in depression: Biological underpinnings, measurement, and treatment

Psychomotor retardation is a long established component of depression that can have significant clinical and therapeutic implications for treatment. Due to its negative impact on overall function in depressed patients, we review its biological correlates, optimal methods of measurement, and relevance in the context of therapeutic interventions. The aim of the paper is to provide a synthesis of the literature on psychomotor retardation in depression with the goal of enhanced awareness for clinicians and researchers. Increased knowledge and understanding of psychomotor retardation in major depressive disorder may lead to further research and better informed diagnosis in regards to psychomotor retardation. Manifestations of psychomotor retardation include slowed speech, decreased movement, and impaired cognitive function. It is common in patients with melancholic depression and those with psychotic features. Biological correlates may include abnormalities in the basal ganglia and dopaminergic pathways. Neurophysiologic tools such as neuroimaging and transcranial magnetic stimulation may play a role in the study of this symptom in the future. At present, there are three objective scales to evaluate psychomotor retardation severity. Studies examining the impact of psychomotor retardation on clinical outcome have found differential results. However, available evidence suggests that depressed patients with psychomotor retardation may respond well to electroconvulsive therapy (ECT). Current literature regarding antidepressants is inconclusive, though tricyclic antidepressants may be considered for treatment of patients with psychomotor retardation. Future work examining this objective aspect of major depressive disorder (MDD) is essential. This could further elucidate the biological underpinnings of depression and optimize its treatment.

Evidence for GABAergic inhibitory deficits in major depressive disorder

Converging evidence suggests that deficits in gamma-aminobutyric acid (GABA) functioning are implicated in the pathophysiology of major depressive disorder (MDD). This is highlighted by research investigating cortical inhibition (CI), a process whereby GABAergic interneurons selectively attenuate pyramidal neurons. Transcranial magnetic stimulation (TMS) paradigms evaluate this marker of neuronal inhibitory activity in the cortex. This review will examine the neuroanatomic and neurophysiological evidence from neuroimaging, molecular, treatment, and TMS studies linking dysfunctional GABAergic neurotransmission to MDD.

Adjunctive use of repetitive transcranial magnetic stimulation in depressed adolescents: a prospective, open pilot study.

OBJECTIVE Depression is often a serious and debilitating illness in adolescents. Unfortunately, a significant number of adolescents do not respond to antidepressant medications or psychotherapy. Repetitive transcranial magnetic stimulation (rTMS) is a novel treatment intervention shown to benefit depression in adults. This study considered rTMS as an adjunctive treatment in adolescents with major depressive disorder. METHOD This prospective, open, multicenter trial of active adjunctive rTMS was conducted with 8 adolescents with DSM-IV-TR major depressive disorder (MDD) that had not responded sufficiently to 2 adequate antidepressant medication trials. All subjects were maintained on a stable dose of a selective serotonin reuptake inhibitor during the trial. Thirty daily rTMS treatments were given 5 days per week over 6 to 8 weeks. rTMS was applied to the left dorsolateral prefrontal cortex (120% of motor threshold; 10 Hz; 4-second trains; 26-second intertrain interval; 75 trains) for a total of 3,000 stimulations per treatment session. RESULTS Seven of 8 adolescents completed all 30 treatments. rTMS was well tolerated, and no significant safety issues were identified. Suicidal ideation was present at baseline in 3 of the adolescents, and it improved during treatment. The primary outcome measure was the Childrens Depression Rating Scale-Revised (CDRS-R); results improved significantly from baseline (mean [SD]) (65.9 [6.6]) to treatment 10 (50.9 [12]), P < .02. The CDRS-R scores continued to improve through the rTMS treatment series at treatment 20 (40.1 [14]), P < .01; treatment 30 (32.6 [7.3]), P < .0001; and at 6-month follow-up (32.7 [3.8]), P < .0001. CONCLUSIONS This prospective open trial suggests that rTMS is a safe, feasible, and potentially effective adjunctive therapy for treatment-resistant MDD in adolescents. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00587639.

Using Simultaneous Repetitive Transcranial Magnetic Stimulation/Functional Near Infrared Spectroscopy (rTMS/fNIRS) to Measure Brain Activation and Connectivity

INTRODUCTION Simultaneously acquiring functional Near Infrared Spectroscopy (fNIRS) during Transcranial Magnetic Stimulation (rTMS) offers the possibility of directly investigating superficial cortical brain activation and connectivity. In addition, the effects of rTMS in distinct brain regions without quantifiable behavioral changes can be objectively measured. METHODS Healthy, nonmedicated participants age 18-50 years were recruited from the local community. After written informed consent was obtained, the participants were screened to ensure that they met inclusion criteria. They underwent two visits of simultaneous rTMS/fNIRS separated by 2 to 3 days. In each visit, the motor cortex and subsequently the prefrontal cortex (5 cm anterior to the motor cortex) were stimulated (1 Hz, max 120% MT, 10 s on with 80 s off, for 15 trains) while simultaneous fNIRS data were acquired from the ipsilateral and contralateral brain regions. RESULTS Twelve healthy volunteers were enrolled with one excluded prior to stimulation. The 11 participants studied (9 male) had a mean age of 31.8 (s.d. 10.2, range 20-49) years. There was no significant difference in fNIRS between Visit 1 and Visit 2. Stimulation of both the motor and prefrontal cortices resulted in a significant decrease in oxygenated hemoglobin (HbO(2)) concentration in both the ipsilateral and contralateral cortices. The ipsilateral and contralateral changes showed high temporal consistency. DISCUSSION Simultaneous rTMS/fNIRS provides a reliable measure of regional cortical brain activation and connectivity that could be very useful in studying brain disorders as well as cortical changes induced by rTMS.

Applications of transcranial magnetic stimulation (TMS) in child and adolescent psychiatry.

Transcranial magnetic stimulation (TMS) is emerging as a new treatment and neurophysiological research tool for psychiatric disorders. Recent publications suggest that this modality will also serve as a treatment and research tool in child and adolescent psychiatry. Current reports on therapeutic trials of repetitive transcranial magnetic stimulation (rTMS) in adolescents have primarily focused on depression. However, other pilot work involves the treatment of attention-deficit/hyperactivity disorder (ADHD), autism and schizophrenia. Neurophysiological studies typically utilize single and paired-pulse TMS paradigms which index cortical excitability and inhibition. Initial studies have focused on ADHD, autism, and depression. General knowledge regarding TMS among child and adolescent psychiatrists is lacking. The aim of this review is to provide an overview of TMS in the context of child and adolescent psychiatry, discuss recent therapeutic and neurophysiological studies, and examine relevant ethical considerations.

Functional connectivity of brain structures correlates with treatment outcome in major depressive disorder

Identifying biosignatures to assess the probability of response to an antidepressant for patients with major depressive disorder (MDD) is critically needed. Functional connectivity MRI (fcMRI) offers the promise to provide such a measure. Previous work with fcMRI demonstrated that the correlation in signal from one region to another is a measure of functional connectivity. In this pilot work, a baseline non-task fcMRI was acquired in 14 adults with MDD who were free of all medications. Participants were then treated for 8 weeks with an antidepressant and then clinically re-evaluated. Probabilistic anatomic regions of interest (ROI) were defined for 16 brain regions (eight for each hemisphere) previously identified as being important in mood disorders. These ROIs were used to determine mean time courses for each individuals baseline non-task fcMRI. The correlations in time courses between 16 brain regions were calculated. These calculated correlations were considered to signify measures of functional connectivity. The degree of connectivity for each participant was correlated with treatment outcome. Among 13 participants with 8 weeks follow-up data, connectivity measures in several regions, especially the subcallosal cortex, were highly correlated with treatment outcome. These connectivity measures could provide a means to evaluate how likely a patient is to respond to an antidepressant treatment. Further work using larger samples is required to confirm these findings and to assess if measures of functional connectivity can be used to predict differential outcomes between antidepressant treatments.

Insomnia moderates outcome of serotonin-selective reuptake inhibitor treatment in depressed youth

OBJECTIVE Insomnia is evident in the majority of youth with depression, and is associated with poorer outcomes. There are limited data on the impact of insomnia in response to acute treatment, which is particularly relevant with serotonin-selective reuptake inhibitors, given their tendency to worsen sleep architecture. METHODS Three hundred nine children and adolescents (ages 7-18 years) were randomized to fluoxetine (n=157) or placebo (n=152) for 8-9 weeks (Emslie et al.1997, 2002). Substantial insomnia at baseline was defined as a childs depression rating scale-revised [CDRS-R] sleep item ≥ 4. Outcome measures were CDRS-R, response, and remission. RESULTS Insomnia was reported in 172/309 (55.7%) youth, and was associated with higher depression severity and greater fatigue, suicidal ideation, physical complaints, and decreased concentration. While response rates were similar in those with or without insomnia overall (51.7% vs. 55.7%), there is a significant difference by age group. Among adolescents, those with insomnia were less likely to respond to fluoxetine (39.2%; 20/51) than those without (65.9%; 27/41; p=0.013), while in children on fluoxetine, those with insomnia were more likely to respond to fluoxetine (69.4%; 25/36) than those without insomnia (41.4%; 12/29; p=0.027). Insomnia did not impact the response to placebo in either age group. Within adolescents, the overall least squares means for CDRS-R total score (across the 8 weeks of treatment) were significantly different between those who had insomnia versus those who did not within the fluoxetine group (43.65 [SE=1.31] vs. 36.58[SE=1.45], F=12.69, df=1, 169, p=0.0005; d=0.82), but not within the placebo group (44.91[SE=1.34] vs. 43.75[SE=1.68], F=0.29, df=1, 179, p=0.591; d=0.15). CONCLUSIONS While adolescents reporting substantial insomnia were less likely to respond to antidepressant treatment than those without insomnia, children were more responsive to fluoxetine when they had insomnia. Additional intervention targeting sleep disturbance may be warranted in adolescents.

The emerging role for repetitive transcranial magnetic stimulation in optimizing the treatment of adolescent depression.

Major depressive disorder (MDD) in adolescents is a common illness and significant public health problem. Treatment is challenging because of recurrences and limited modalities. Selective serotonin reuptake inhibitors and cognitive behavioral therapy are considered the standard of care in severe or treatment-resistant MDD in this age group. However, responses to these interventions are often suboptimal. A growing body of research supports the efficacy of repetitive transcranial magnetic stimulation (rTMS) for the treatment of MDD in adults. Induced seizures are a primary safety concern, although this is rare with appropriate precautions. There is, however, limited experience with rTMS as a therapeutic intervention for adolescent psychiatric disturbances. This review will summarize the rTMS efficacy and safety data in adults and describe all published experience with adolescent MDD. Applications in other adolescent psychiatric illnesses such as schizophrenia and attention-deficit/hyperactivity disorder are reviewed. Safety and ethical issues are paramount with investigational treatments in adolescent psychiatric illnesses. However, further research with rTMS in adolescent MDD is imperative to establish standards for optimal stimulation site, treatment parameters, and its role in treatment algorithms. These may diverge from adult data. Early intervention with neuromodulation could also hold the promise of addressing the developmental course of dysfunctional neurocircuitry.

Evidence for Increased Glutamatergic Cortical Facilitation in Children and Adolescents With Major Depressive Disorder

CONTEXT Converging lines of evidence implicate the glutamate and γ-aminobutyric acid neurotransmitter systems in the pathophysiology of major depressive disorder. Transcranial magnetic stimulation cortical excitability and inhibition paradigms have been used to assess cortical glutamatergic and γ-aminobutyric acid-mediated tone in adults with major depressive disorder, but not in children and adolescents. OBJECTIVE To compare measures of cortical excitability and inhibition with 4 different paradigms in a group of children and adolescents with major depressive disorder vs healthy controls. DESIGN Cross-sectional study examining medication-free children and adolescents (aged 9-17 years) with major depressive disorder compared with healthy controls. Cortical excitability was assessed with motor threshold and intracortical facilitation measures. Cortical inhibition was measured with cortical silent period and intracortical inhibition paradigms. SETTING University-based child and adolescent psychiatry clinic and neurostimulation laboratory. PATIENTS Twenty-four participants with major depressive disorder and 22 healthy controls matched for age and sex. Patients with major depressive disorder were medication naive and had moderate to severe symptoms based on an evaluation with a child and adolescent psychiatrist and scores on the Childrens Depression Rating Scale-Revised. MAIN OUTCOME MEASURES Motor threshold, intracortical facilitation, cortical silent period, and intracortical inhibition. RESULTS Compared with healthy controls, depressed patients had significantly increased intracortical facilitation at interstimulus intervals of 10 and 15 milliseconds bilaterally. There were no significant group differences in cortical inhibition measures. CONCLUSIONS These findings suggest that major depressive disorder in children and adolescents is associated with increased intracortical facilitation and excessive glutamatergic activity.

KETAMINE FOR TREATMENT‐RESISTANT UNIPOLAR AND BIPOLAR MAJOR DEPRESSION: CRITICAL REVIEW AND IMPLICATIONS FOR CLINICAL PRACTICE

There is an urgent need for more rapidly effective pharmacotherapies for major depressive disorder and bipolar disorder (BP) that are efficacious and tolerable for depressed patients who respond poorly to conventional treatments. Multiple controlled trials have now demonstrated a rapid, nonsustained antidepressive response to a single intravenous infusion of ketamine. Early controlled studies of intranasal or serial infusion therapy appear promising. The effective dose for depression is lower than the typical anesthetic doses, and side‐effects are generally mild and transient. The data investigating the adjunctive use of concurrent ketamine in the course of electroconvulsive therapy (ECT) for depression do not suggest efficacy or tolerability. The therapeutic potential of ketamine has stimulated considerable excitement among clinicians, patients, and industry, and has led to the increasing use of ketamine as an off‐label substitute for ECT and other antidepressive treatments. This clinical review of ketamine will assess the evidence‐based use of ketamine and initial clinical implications of further development of a potentially novel treatment for rapid reduction of symptoms in depressed patients.