Development of a voltage controlled resistor for use in a self-balancing resistance bridge

We report on a simple design for a voltage controlled resistor that can operate in a continuous range from ∼50 Ω to over ∼100 kΩ. The device consists of a light emitting diode (LED) placed near a photocell. Varying the voltage across the LED changes its brightness, which, in turn, changes the resistance of the photocell. The resistance of the photoresistor is measured by calibrating the output of a nearby phototransistor against the photoresistor resistance, allowing for an independent measurement of the resistance. The performance of the device is tested in the context of a temperature measuring system involving a Wheatstone bridge.

A meta-analysis of executive dysfunctions in unipolar major depressive disorder without psychotic symptoms and their changes during antidepressant treatment

OBJECTIVE

Empirical evidence supports the existence of significant executive deficits in patients with major depressive disorder (MDD) as compared to non-depressed controls. Nevertheless, the effect size of executive dysfunctions in unipolar, non-psychotic MDD as well as their relationship to antidepressant treatment is ambiguous.

METHOD

Meta-analytic methods were used to assess the severity of executive dysfunctions in unipolar, non-psychotic MDD as compared to healthy controls and to investigate their course during antidepressant treatment.

RESULTS

Fifteen studies comparing the executive functions of 375 patients with DSM-IV MDD and 481 healthy controls were analysed. Furthermore, in three studies, including 122 patients with MDD, the Stroop test performance was examined before and after antidepressant treatment. Patients with MDD performed 0.439 up to 1.18 (P < 0.0001) standard mean differences worse than healthy controls. The Stroop performance improved during the course of treatment (P = 0.0001).

CONCLUSION

We revealed significant executive dysfunctions in patients with unipolar, non-psychotic MDD compared with healthy controls and an improvement of the Stroop performance during the course of treatment. Future studies with different test procedures are needed to further investigate the influence of antidepressant treatment on executive functions.

The serotonin transporter promoter polymorphism (5-HTTLPR) affects the relation between antidepressant serum concentrations and effectiveness in major depression

INTRODUCTION

Both the serotonin transporter promotor polymorphism (5-HTTLPR) and serum concentrations of SSRIs have been shown to affect response to SSRIs. Results, however, are inconsistent. The aim of this study was to investigate whether remission or response to SSRIs is influenced by an interaction of 5-HTTLPR and SSRI serum concentrations.

METHODS

49 patients with major depression and SSRI treatment were genotyped for the 5-HTTLPR locus including the rs25531. Drug serum concentrations and depression severity were measured weekly.

RESULTS

Logistic regression analysis revealed a significant association between 5-HTTLPR, SSRI serum concentrations and response to treatment. A favourable treatment outcome correlated with SSRI serum concentration in 5-HTTLPR-L(A) allele carriers (r² = 34.3 %; p = 0.001), but not in S/L(G)-allele carriers (p = 0.31).

DISCUSSION

In the group of L(A) allele carriers, those MDD patients with a high antidepressant serum concentrations responded better to treatment than patients with a low serum concentration. We conclude that the 5-HTTLPR might affect reponse to SRRI subject to serum concentrations. If replicated this might be a starting point for prospective clinical trials.

The inventory of depressive symptomatology is more sensitive to changes in depressive symptomatology than the hamilton depression rating scale in patients with minor depression

Background

Depression rating scales play a decisive role in the assessment of the severity of depression and the evaluation of the efficacy of antidepressant treatments. The Hamilton Depression Rating Scale (HAMD) is regarded as the ‘gold standard’; nevertheless, studies suggest that the Inventory of Depressive Symptomatology (IDS) is more sensitive to detect symptom changes. The aim of the present study was to investigate whether the IDS is more sensitive in detecting changes in depression symptoms in patients with mild major, minor or subsyndromal depression (MIND).

Methods

Biweekly IDS-C28 and HAMD17 data from 340 patients of a 10-week randomized, placebo-controlled trial comparing the effectiveness of sertraline and cognitive-behavioural therapy in patients with MIND were analysed. We investigated sensitivity to change for both scales1)

Results

The IDS-C28 was more sensitive in detecting changes in depression symptomatology over the treatment course as well as for different severity levels, especially in patients with a low depression severity. It assesses the DSM-IV criteria more thoroughly, is better able to track the change of cognitive symptoms and to identify residual symptoms.

Conclusions

Both scales are well able to assess depressive symptomatology. However, the IDS-C28 surpasses the HAMD17 in detecting small changes especially in the core symptoms of depression. This is important for an optimal treatment by capturing early improvements, enabling prompt reactions and detecting residual symptoms.

The catechol o-methyltransferase (COMT) val(158)met polymorphism modulates the association of serious life events (SLE) and impulsive aggression in female patients with borderline personality disorder (BPD)

OBJECTIVE

We analyzed i) the effects of serious life events (SLE) on impulsive aggression, and ii) modulating effects of the COMT Val(158)Met polymorphism on the association between SLEs and impulsive aggression in borderline personality disorder (BPD).

METHOD

One hundred and twelve female BPD patients from Germany were included in this study. Impulsive aggression was assessed by the Buss-Durkee-Hostility Inventory (BDHI).

RESULTS

Childhood sexual abuse was associated with lower BDHI sum score (P = 0.003). In COMT Val(158)Val carriers, but not in Val/Met and Met/Met carriers, childhood sexual abuse and the cumulative number of SLEs were associated with lower BDHI sum scores (P < 0.05).

CONCLUSION

This study analyzing a specific gene x environment interaction in female BPD patients suggests an association between SLEs and impulsive aggression, as well as a modulating effect of the COMT Val(158)Val genotype on the relation between SLEs and impulsive aggression.

Modulatory role of the brain-derived neurotrophic factor Val66Met polymorphism on the effects of serious life events on impulsive aggression in borderline personality disorder

Impulsive aggression belongs to the key features of borderline personality disorder (BPD). In the development of BPD, serious life events are known to play a major role. Acute and chronic stress has been suggested to inhibit hippocampal brain-derived neurotrophic factor (BDNF) synthesis and to mediate neural plasticity in response to adverse social experiences. Recently it has been reported that the frequency of violent suicide attempts is higher in adult suicide attempters reporting severe childhood sexual abuse and carrying the Val(66)Val genotype of the BDNF Val(66)Met polymorphism. In this study we analysed modulating effects of BDNF Val(66)Met polymorphism on the effects of physical maltreatment, rape and childhood sexual abuse on impulsive aggression. One hundred and fifty-nine BPD patients from Germany and of Caucasian descent were included. Impulsive aggression was assessed by the Buss-Durkee-Hostility Inventory (BDHI). Childhood sexual abuse accounted for 23.6% of the variance of BDHI sum score. Childhood sexual abuse decreased BDHI sum score in BDNF Val/Val carriers but not in Met carriers. In contrast to previous findings this study analysing a specific gene x environment interaction in BPD patients suggests a decreasing effect of childhood sexual abuse on impulsive aggression in BPD patients, particularly in BDNF Val/Val carriers. The interrelations between serious life events, impulsive aggression and the BDNF Val(66)Met polymorphism as well as their implication for BPD are far from understood and require further investigations.

[Pharmacological therapy for therapy-resistant depression. New developments]

Remission, i.e. the complete absence of symptoms, is the major goal in the treatment of major depressive disorders because residual symptoms cause less functioning and a worse outcome. Despite several treatment steps, numerous patients do not reach complete remission of symptoms. In these patients, it is necessary to rule out several possible causes, including inadequate pharmacotherapy, to confirm the diagnosis of treatment-resistant depression (TRD). In the treatment of TRD, pharmacotherapy plays a central role. Nonpharmacological treatment strategies such as psychotherapy, electroconvulsive therapy, and other brain stimulation methods are also used for TRD treatment and are discussed elsewhere in this issue. Regarding complex pharmacotherapy of TRD, only a limited number of randomized-controlled trials have been done. In consequence, treatment decisions are often based on clinical experience, case series, and uncontrolled studies. Nevertheless, there are some interesting new developments, which are summarized and assessed on the basis of existing evidence in this article. Afore, we present an overview of the most important definitions, epidemiologic data, diagnostic needs and methods for treatment optimization. We end with a critical view on the present and future development of antidepressant drugs.