A sequential double-blind controlled study of moclobemide and diazepam in patients with atypical depression

Genetic and pharmacological inactivation of astroglial connexin 43 differentially influences the acute response of antidepressant and anxiolytic drugs

AIM

Astroglial connexins (Cxs) 30 and 43 are engaged in gap junction and hemichannel activities. Evidence suggests that these functional entities contribute to regulating neurotransmission, thereby influencing brain functions. In particular, preclinical and clinical findings highlight a role of Cx43 in animal models of depression. However, the role of these proteins in response to currently available psychotropic drugs is still unknown.

METHODS

To investigate this, we evaluated the behavioural effects of the genetic and pharmacological inactivation of Cx43 on the antidepressant- and anxiolytic-like activities of the selective serotonin reuptake inhibitor fluoxetine and the benzodiazepine diazepam, respectively.

RESULTS

A single administration of fluoxetine (18 mg/kg; i.p.) produced a higher increase in hippocampal extracellular serotonin levels, and a greater antidepressant-like effect in the tail suspension test in Cx43 knock-down (KD) mice bred on a C57BL/6 background compared to their wild-type littermates. Similarly, in outbred Swiss wild-type mice, the intra-hippocampal injection of a shRNA-Cx43 or the acute systemic injection of the Cxs inhibitor carbenoxolone (CBX: 10 mg/kg; i.p.) potentiated the antidepressant-like effects of fluoxetine. Evaluating the effects of such strategies on diazepam (0.5 mg/kg; i.p.), the results indicate that Cx43 KD mice or wild-types injected with a shRNA-Cx43 in the amygdala, but not in the hippocampus, attenuated the anxiolytic-like effects of this benzodiazepine in the elevated plus maze. The chronic systemic administration of CBX mimicked the latter observations.

CONCLUSION

Collectively, these data pave the way to the development of potentiating strategies in the field of psychiatry based on the modulation of astroglial Cx43.

Atypical depression: a comprehensive review

Despite several decades of research, the characteristics distinguishing atypical depression from other depressive subtypes remain ambiguous. Multiple lines of evidence support the designation of atypical depression as a scientifically and clinically relevant subtype, including differences in hormonal responses, brain laterality, psychological profile and psychiatric co-morbidity and differential treatment response. The evolution of the diagnostic criteria for atypical depression has led to the designation of mood reactivity as the cardinal feature, and the research supporting this conclusion is reviewed. This paper also reviews the evidence for the drug treatment of atypical depression, with a particular focus on research related to the superior efficacy of monoamine oxidase inhibitors (MAOIs) compared with tricyclic antidepressants (TCAs). Data relevant to the efficacy of newer antidepressants, including selective serotonin reuptake inhibitors (SSRIs), serotonin-noradrenaline (norepinephrine) reuptake inhibitors, transdermal selegiline and other new agents for atypical depression, are discussed. In summary, the diagnostic reliability and validity of atypical depression still remain elusive and open to further evolution. Currently available findings suggest that atypical depression has preferential response to MAOIs over TCAs. More data are required to determine the efficacy of newer agents relative to MAOIs and TCAs, although limited studies have shown a non-inferior efficacy and better tolerability of newer agents such as SSRIs compared with those of MAOIs and TCAs. Finally, future directions for research include further refinement of the diagnostic criteria for atypical depression, and clarification of the role of newer antidepressants in the treatment of this subtype with evidence from randomized, controlled trials.

Treatment of depression with atypical features: a meta-analytic approach

The present meta-analysis addressed the empirical evidence regarding the treatment of major depression with atypical features. The superiority of monoamine oxidase inhibitors (MAOIs) compared with other antidepressants in the treatment of major depression with atypical features has been frequently reported. According to the CONSORT Statement, studies included in our meta-analysis had to meet several criteria, especially a double-blind, controlled condition and an operational diagnosis according to Diagnostic and Statistical Manual of Mental Disorders (DSM)-III or DSM-IV criteria, respectively. Four databases for research-based evidence were used in a systematic review: Medline, Embase, Psyndex and PsycInfo. Only eight publications met inclusion/exclusion criteria, resulting in 11 comparisons. Our results contrast an effect size of 0.45 (95% confidence interval) for a comparison of MAOIs vs. placebo with an effect size of 0.02 (95% confidence interval: - 0.10-0.14) for a comparison of MAOIs vs. selective serotonin reuptake inhibitors. The effect size for MAOIs vs. tricyclic antidepressants was 0.27 (95% confidence interval: 0.16-0.42). MAOIs may be more effective for atypical major depressive disorder than tricyclic antidepressants. Most clinical research has been conducted on irreversible MAOIs. Additional studies testing more recently developed antidepressants (including reversible MAOIs) with an improved safety profile would be warranted. The available data are insufficient for a direct comparison between MAOIs and selective serotonin reuptake inhibitors.

Depressive subtypes and efficacy of antidepressive pharmacotherapy

Efficacy studies suggest that all kinds of treatment have similar efficacy. For instance, according to a meta-analysis from 102 randomised controlled trials in major depression, there is no overall difference in efficacy between SSRIs and TCAs. Taking into consideration the pathophysiological heterogeneity of affective disorders involving a number of neurotransmitters, the different pharmacodynamic profiles of the antidepressant compounds, and the large variety of presentations of depressive illness, it is very simplistic to suppose that all classes of antidepressants are equally effective. Meanwhile, the development of antidepressants with different mechanisms of action provides the opportunity to evaluate whether certain relevant subtypes of depressed patients, based on specific patterns of symptoms, respond preferentially to one class of antidepressants compared with another. The aim of this paper is to review the relationship between the depressive subtypes included in the DSM-IV (melancholic depression, atypical depression, bipolar depression, psychotic bipolar and dysthymia) and the efficacy of antidepressant treatment.

Atypical depression spectrum disorder - neurobiology and treatment

Depressive syndromes are a group of heterogeneous disorders. Atypical depression (AD) with reversed vegetative signs, such as hyperphagia or hypersomnia, is traditionally neglected, demonstrated by the fact that in the most widely used depression scales, such as the Hamilton Depression Scale (HAMD), melancholic symptoms have a specific weight, while, by contrast, reversed vegetative signs are not included. However, epidemiologically and phenomenologically related disorders to AD do exist, such as somatoform disorders, neurasthenia (chronic fatigue syndrome) and fibromyalgia (FM). In this spectrum, here called the AD spectrum, instead a decrease in hypothalamus-pituitary-adrenocortical (HPA) axis activity seems to exist. This has similarities to Cushing's disease, where a suppression of central HPA system activity is accompanied by features of AD and somatization in a considerable number of patients. Opposite vegetative features might therefore be related to the opposite dysregulation of the HPA system. The psychopharmacological intervention in the AD spectrum should therefore differ from that used in typical major depression. MAO inhibitors, low-dose tricyclic antidepressants and 5-HT3 antagonists demonstrated therapeutic efficacy, but the existing studies focused on different aspects. Hypericum extracts might be an alternative pharmacological intervention, which demonstrated therapeutic efficacy in the symptom range of the spectrum.

A 12-week study comparing moclobemide and sertraline in the treatment of outpatients with atypical depression

One hundred and ninety-seven outpatients with atypical depression [Atypical Depression Diagnostic Scale (ADDS) score=4] were randomized to 12 weeks of double-blind treatment with sertraline or moclobemide in a multicentre, parallel-group clinical trial. Patients were started on either 50 mg/day sertraline or 300 mg/day moclobemide. If the therapeutic response was not satisfactory after 4 weeks, the dose could be increased to either 100 mg/day sertraline or 450 mg/day moclobemide. Primary efficacy evaluations were the 29-item Hamilton Psychiatric Rating Scale for Depression (HAM-D) and the Clinical Global Impression of Improvement (CGI-I) response rate (much or very much improved) at study endpoint. Secondary efficacy evaluations included the ADDS, the Hamilton Anxiety Scale (HAMA), the Leeds Sleep Scale, and the Battelle Quality of Life Battery (BQOLB). In the analysis of the 172 patient efficacy-evaluable population, there was significant baseline to endpoint improvement in all primary and secondary efficacy assessments after treatment with either sertraline or moclobemide. At the endpoint, the proportion of responders on CGI-I, was 77.5% in the sertraline group and 67.5% in the moclobemide group (p=0.052). The baseline to endpoint mean 29-item HAM-D score decreased from 35.9 to 14.5 in the sertraline group and from 36.3 to 16.1 in the moclobemide group. Sertraline also resulted in a significantly (p < 0.05) greater degree of improvement at the endpoint, compared with moclobemide, in the proportion of remitters on the HAMA (total score < or = 7), ADDS Category IID (Rejection Sensitivity), Leeds Sleep Factor 4 (Integrity of Behaviour Following Awakening), and on three dimensions of the BQOLB (Energy/Vitality, Social Interaction and Life Satisfaction). There were no other significant differences between treatment groups. Overall, both medications were well tolerated. In this study, both sertraline and moclobemide improved the symptoms of atypical depression.

The validity of atypical depression in DSM-IV

Atypical depression has been included in the DSM-IV as an episode specifier of major depressive episodes and dysthymia. This report will review evidence for the clinical validity of atypical depression using operational criteria for the validation of clinical syndromes. English language articles between 1969 and March 1996 were found using a computerized and manual reference search and were selected according to the following criteria: (1) primary research, (2) definition of atypical depression, which includes depression and not anxiety alone, and (3) relevance of data for validation of atypical depression. Studies were evaluated on Kendall's six criteria for establishing clinical validity. There are supporting data for diagnostic validity of atypical depression in the criteria of clinical description and differential treatment response, with atypical depression having a superior response to monoamine oxidase (MAO) inhibitors compared to tricyclic antidepressants. There is still only limited support for the validity of atypical depression in the criteria of pathophysiology, points of rarity with other similar diagnoses, distinctive course and outcome, and genetics. Based on the current evidence, atypical depression is a useful diagnostic concept, particularly for predicting differential drug response, but further research is required to conclusively demonstrate its validity as a clinical syndrome.

Moclobemide and fluoxetine in atypical depression: a double-blind trial

The effectiveness of moclobemide or fluoxetine in the treatment of atypical (n = 53) and other depressive patients (n = 156) was compared in a 6-week double-blind randomized trial. HDRS, MARDS, GCI and the Atypical Depression Diagnostic Scale were used in clinical assessment. Significant differences were seen in MADRS and GCI scores in favour of moclobemide in the treatment of atypical depression, but not with HDRS. No major differences were seen between the two drugs in the treatment of other depressive patients. A positive response, defined by a > 50% decrease in HDRS score and a GCI Improvement Score of 1 or 2, was seen among 67% of atypical patients treated with moclobemide and among 55% treated with fluoxetine and in 60 and 48% of other depressive patients, respectively. Both drugs gave results with atypical patients at least as good as with other depressive patients. Our results suggest that patients suffering from atypical depression may respond more favourably to moclobemide than to fluoxetine treatment.

Antidepressants, alcohol and psychomotor performance

The acute psychomotor effects of moclobemide, a reversible inhibitor of MAO-A antidepressant (100 and 300 mg) compared with amitriptyline (25 and 75 mg) showed that moclobemide caused no significant impairment in contrast with amitriptyline, which caused significant impairment at both doses. Two other studies are reviewed. One study reported the acute effects of moclobemide (100 and 300 mg), trazodone (100 mg), placebo, and alcohol (0.5 g/kg) or placebo in an elderly group: moclobemide caused little impairment or alcohol potentiation and may reverse some alcohol impairment, whereas trazodone caused substantial impairment and alcohol potentiation. Another study of the acute and chronic effects of moclobemide (200 mg 3 times daily) or clomipramine (25 mg twice daily) and their interactions with alcohol (blood alcohol concentration 0.6 g/l) showed that alcohol caused significant impairment, whereas clomipramine tended to enhance and moclobemide to reduce some impairment. Moclobemide appears to be an antidepressant with few psychomotor effects and minimal alcohol potentiation and may reduce some alcohol impairment.

Reversible and irreversible monoamine oxidase inhibitors in other psychiatric disorders

In addition to being effective in depressive disorders, monoamine oxidase inhibitors (MAOIs) have been shown to be effective in controlled studies of patient with panic disorder with agoraphobia, social phobia, atypical depression or mixed anxiety and depression, bulimia, posttraumatic stress disorder (PTSD) and borderline personality disorder. Uncontrolled case reports have noted MAOI efficacy in obsessive-compulsive disorder (OCD), trichotillomania, dysmorphophobia and avoidant personality disorder. Reversible inhibitors of MAO-A (RIMAs) appear safer than the classical irreversible MAOIs since they have less potential to increase blood pressure. They have not been studied as yet, however, in most of the conditions responsive to MAOIs. If RIMAs are found effective in these disorders, they would probably achieve wider use than MAOIs because they are safer and tend to cause fewer side effects.

The new and newer antianxiety agents

Anxiolytic drugs are adjuncts to non-pharmacological treatments for anxiety. Alcohol and tobacco remain the major psychoactive agents that are used in our community. Benzodiazepine drugs are the agents of choice if an acute reduction in anxiety or intermittent therapy is needed and are helpful for long-term use in a few patients. For panic disorders, alprazolam is effective for short- and long-term treatment, although it needs a slow reduction in dosage and carries a risk of withdrawal reactions in about 30% of sufferers. Clonazepam also may help panic attacks and possibly other benzodiazepine agents would show similar effects at equivalent doses. Antidepressant drugs, including monoamine-oxidase inhibitor agents, although more toxic and sometimes less tolerated than is alprazolam, have antipanic effects in high doses and are of use for prolonged therapy for panic disorders. Neuroleptic agents' general usefulness as anxiolytic drugs is restricted because of their acute and long-term toxicity. There is no place for the use of antidepressant or neuroleptic drugs as treatments of first choice in uncomplicated generalized anxiety. beta-blocking agents have limited adjunctive use for performance anxiety and social phobias. Buspirone heralds a new class of anxiolytic agents. Buspirone has advantages in patients who can tolerate its slow onset of action, with reduced psychomotor effects, lower interactive effects with cortical depressant substances and a seeming lack of dependency or any withdrawal syndrome.

Is diazepam an antidepressant?

In double-blind sequential study, diazepam was compared with the proven antidepressant moclobemide, in patients with atypical depression. Both agents significantly improved depression ratings over eight weeks of treatment. Diazepam was a significantly better antidepressant than moclobemide at four week, although not at eight weeks. All patients ceased diazepam within one year and none reported withdrawal reactions. These data suggest the need to reconsider that benzodiazepines may be antidepressants and to study their possible antidepressant actions.