Neurophysiologic effects of repeated exposure to antidepressant medication: Are brain functional changes during antidepressant administration influenced by learning processes?

Normative Structure of Resting-State EEG in Bipolar Derivations for Daily Clinical Practice: A Pilot Study

We used numerical methods to define the normative structure of resting-state EEG (rsEEG) in a pilot study of 37 healthy subjects (10-74 years old), using a double-banana bipolar montage. Artifact-free 120-200 s epoch lengths were visually identified and divided into 1 s windows with a 10% overlap. Differential channels were grouped by frontal, parieto-occipital, and temporal lobes. For every channel, the power spectrum was calculated and used to compute the area for delta (0-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), and beta (13-30 Hz) bands and was log-transformed. Furthermore, Shannon's spectral entropy (SSE) and coherence by bands were computed. Finally, we also calculated the main frequency and amplitude of the posterior dominant rhythm. According to the age-dependent distribution of the bands, we divided the patients in the following three groups: younger than 20; between 21 and 50; and older than 51 years old. The distribution of bands and coherence was different for the three groups depending on the brain lobes. We described the normative equations for the three age groups and for every brain lobe. We showed the feasibility of a normative structure of rsEEG picked up with a double-banana montage.

ADHD: Reviewing the Causes and Evaluating Solutions

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder in which patients present inattention, hyperactivity, and impulsivity. The etiology of this condition is diverse, including environmental factors and the presence of variants of some genes. However, a great diversity exists among patients regarding the presence of these ADHD-associated factors. Moreover, there are variations in the reported neurophysiological correlates of ADHD. ADHD is often treated pharmacologically, producing an improvement in symptomatology, albeit there are patients who are refractory to the main pharmacological treatments or present side effects to these drugs, highlighting the importance of developing other therapeutic options. Different non-pharmacological treatments are in this review addressed, finding diverse results regarding efficacy. Altogether, ADHD is associated with different etiologies, all of them producing changes in brain development, leading to the characteristic symptomatology of this condition. Given the heterogeneous etiology of ADHD, discussion is presented about the convenience of personalizing ADHD treatment, whether pharmacological or non-pharmacological, to reach an optimum effect in the majority of patients. Approaches to personalizing both pharmacological therapy and neurofeedback are presented.

In patients suffering from major depressive disorders, quantitative EEG showed favorable changes in left and right prefrontal cortex

BACKGROUND

Patients suffering from major depressive disorders (MDD) report anhedonia, low concentration and lack of goal-oriented behavior. Data from imaging and quantitative EEG (QEEG) studies show an asymmetry in the prefrontal cortex (PFC), with lower left as compared to right PFC-activity, associated with specific depression-related behavior. Cordance is a QEEG measurement, which combines absolute and relative power of EEG-spectra with strong correlations with regional perfusion. The aim of the present study was to investigate to what extent a four weeks lasting treatment with a standard SSRI had an influence on neuronal activation and MDD-related symptoms.

METHOD

Twenty patients suffering from severe MDD were treated with citalopram (40mg) for four consecutive weeks. At baseline and at the end of the treatment, patients underwent QEEG. Experts rated the degree of depression with the Hamilton Depression Rating Scale (HDRS).

RESULTS

Over time, theta cordance increased over right ventromedial and left dorsolateral PFC, whereas alpha cordance decreased over dorsolateral PFC. Improvement in MDD-related symptoms was higher in patients showing decreased EEG theta cordance over right dorsal PFC and increased EEG alpha cordance over left dorsolateral PFC.

CONCLUSIONS

In patients suffering from MDD, treatment response was associated with favorable changes in neuronal activity.

The effects of levomilnacipran ER in adult patients with first-episode, highly recurrent, or chronic MDD

BACKGROUND

Major depressive disorder (MDD) can be challenging to manage due its variable and episodic nature. Post hoc analyses were conducted on five studies (NCT00969709, NCT01377194, NCT00969150, NCT01034462, EudraCT:2006-002404-34) to evaluate the efficacy of levomilnacipran extended-release (ER) in patients with different MDD episode histories.

METHODS

Adults with MDD were randomized to double-blind treatment with levomilnacipran ER (40-120mg/d) or placebo. Three subgroups were identified: first-episode (n=494); highly recurrent (≥3 major depressive episodes; n=1954); and chronic (current episode duration ≥2 years; n=218). Mean changes from baseline to end of study (Week 8 [US studies], Week 10 [non-US study]) in Montgomery-Åsberg Depression Rating Scale (MADRS), 17-item Hamilton Depression Rating Scale (HAMD17), and Sheehan Disability Scale (SDS) total scores were analyzed in each subgroup. MADRS response, defined as ≥50% total score improvement from baseline to Week 8/10, was also analyzed.

RESULTS

Least squares mean differences (LSMDs) between treatment groups indicated significantly greater improvements with levomilnacipran ER versus placebo in MADRS (first-episode, -2.5; highly recurrent, -3.0; chronic, -4.9; all P<.05) and HAMD17 (first-episode, -2.1; highly recurrent, -1.6; chronic, -2.6; all P<.05) total scores. LSMDs for SDS total score were statistically significant in the first-episode and highly recurrent MDD subgroups (both subgroups, -2.3; P<.01). MADRS response rate was significantly higher with levomilnacipran ER versus placebo in all three subgroups (first-episode, 44.5% versus 35.0%; highly recurrent, 44.3% versus 33.5%; 36.8% versus 22.0%; all P<.05).

LIMITATIONS

MDD subgroups were defined post hoc; none of the studies were prospectively designed to evaluate outcomes in these subgroups. Other limitations include lack of active comparators and variability of dose/duration due to data being pooled from multiple clinical trials.

CONCLUSIONS

Results suggest that levomilnacipran ER improves depression symptoms and functional impairment in adult patients with different histories of MDD episodes.

Antidepressant treatment history and drug-placebo separation in a placebo-controlled trial in major depressive disorder

RATIONALE

A history of antidepressant treatment may predispose subjects toward placebo nonresponse in randomized controlled trials (RCTs) in major depressive disorder (MDD).

OBJECTIVE

The objective of this study is to examine self-reported prior antidepressant treatment and response in relationship to clinical outcome in an 8-week randomized trial of reuptake inhibitor antidepressant medication (MED) versus placebo (PBO) administered along with limited supportive care.

METHODS

Chi-square and MMRM analyses examined MED vs. PBO outcomes in antidepressant-naïve vs. antidepressant-experienced subjects. Linear regression models examined treatment history along with covariates as predictors of clinical improvement.

RESULTS

Among completers (n = 56), there was no significant difference in response rate between MED (53.3 %) and PBO (42.3 %) (χ (2) = 0.33, p = 0.28, 1-tailed). The antidepressant-experienced subgroup (n = 37), however, showed a significantly greater response rate to MED (52.4 %) than PBO (25.0 %) (χ (2) = 2.82, p = 0.047, 1-tailed). The full intent-to-treat (ITT) sample (n = 69) did not show a significant difference between MED and PBO group improvement over time, but in the treatment-experienced subgroup (n = 46), MED showed significantly greater improvement than PBO (coefficient = .39, SE = .23, p = .045, 1-tailed). A history of prior antidepressant treatment predicted poorer overall response independent of pretreatment symptom severity, number or length of previous episodes, subject expectations, or family history of MDD.

CONCLUSIONS

Treatment history appears to constitute a factor that is distinct from other commonly studied illness characteristics or expectancy measures, and that impacts overall response as well as drug-placebo separation in RCTs.