Memory performance in panic disorder patients after chronic use of clomipramine

Vortioxetine Improves Context Discrimination in Mice Through a Neurogenesis Independent Mechanism

Major Depressive Disorders (MDD) patients may exhibit cognitive deficits and it is currently unclear to which degree treatment with antidepressants may affect cognitive function. Preclinical and clinical observations showed that vortioxetine (VORT, an antidepressant with multimodal activity), presents beneficial effects on aspects of cognitive function. In addition, VORT treatment increases adult hippocampal neurogenesis (AHN) in rodents, a candidate mechanism for antidepressant activity. Pattern separation (PS) is the ability to discriminate between two similar contexts/events generating two distinct and non-overlapping representations. Impaired PS may lead to overgeneralization and anxiety disorders. If PS impairments were described in depressed patients, the consequences of antidepressant treatment on context discrimination (CD) are still in its infancy. We hypothesized that VORT-increased AHN may improve CD. Thus, in an attempt to elucidate the molecular mechanism underpinning VORT treatment effects on CD, a rodent model of PS, the role of AHN and stress-induced c-Fos activation was evaluated in the adult mouse hippocampus. Chronic treatment with VORT (1.8 g/kg of food weight; corresponding to a daily dose of 10 mg/kg, 3 weeks) improved CD in mice. Interestingly, chronic treatment with VORT reversed ablation of AHN-induced delay in CD and freezing behavior. VORT treatment decreased stress-induced c-Fos activation in the dorsal but not ventral dentate gyrus. VORT treatment did not affect c-Fos activity in the hippocampus of mice with ablated neurogenesis. This study highlights a role of VORT in CD, which may be independent from AHN and hippocampal c-Fos activation. Further studies elucidating the mechanisms underlying VORT’s effects in CD could contribute to future strategies for alleviating the disease burden for individuals suffering from depression and/or anxiety disorders.

Serum level of venlafaxine is associated with better memory in psychotic disorders

Cognitive impairment is a core feature of psychosis spectrum disorders. Antipsychotics have at best small positive effects on cognitive performance. There is a lack of knowledge regarding the effects of antidepressants on cognitive functioning in these disorders. In the present study cognitive performance was investigated in relation to serum levels of antidepressants in persons with bipolar disorder and schizophrenia. Serum concentrations of escitalopram, citalopram and venlafaxine plus O-desmethylvenlafaxine were measured in a total of 187 participants with bipolar disorder (N=74) or schizophrenia spectrum disorders (N=113), and analyzed in relation to neuropsychological tests performance of verbal learning, verbal memory, attention, working memory, executive functioning and processing speed. Analyses were performed using linear regression adjusting for a range of confounders. There was a significant positive association between the serum level of venlafaxine plus O-desmethylvenlafaxine and verbal memory (immediate recall: Logical Memory Test immediate recall [p=0.015], and long term delayed recall: Logical Memory Test delayed recall [p=0.011]). No significant associations were seen between citalopram or escitalopram and verbal memory. There were no significant associations between the tested antidepressants and verbal learning, attention, working memory, executive functioning, or processing speed. Venlafaxine seem to be associated with better verbal memory in bipolar disorder and schizophrenia. This suggests a possible beneficial role of certain antidepressants on cognitive dysfunction, which may have clinical implications and provide insight into underlying pathophysiology. However, the current findings should be replicated in independent samples.

Metabolic and toxicological considerations for obsessive-compulsive disorder drug therapy

INTRODUCTION

Obsessive-compulsive disorder (OCD) affects the daily life of the patients. Chronic nature of this disease and the need for long-term high-dose drug therapy for its maintenance increase the risk of metabolic and toxicological complications.

AREAS COVERED

In this concise article, the metabolic and toxicological aspects of major medication categories prescribed in OCD, such as serotonin-specific reuptake inhibitors, tricyclic antidepressant (clomipramine), serotonin-norepinephrine reuptake inhibitors, and atypical antipsychotics indicated in OCD (both Food and Drug Administration-approved and off-label) are discussed.

EXPERT OPINION

The most critical point in pharmacotherapy of OCD is the need for the high-dose and long-term use of drugs. In OCD, generally the higher doses of applicable drugs than those used in depression are required, often exceeding the recommended maximum dose. Moreover, such high doses should be given for at least 10 - 12 weeks to ensure the adequate treatment duration for the clinical effects to emerge. This long-term high-dose maintenance therapy increases the risk of drug toxicity and adverse effects. Physicians should take extra care in periodical assessment of signs and symptoms of metabolic and toxicological complications in patients. Subjective symptoms reported by patients should be carefully assessed and not attributed to obsessive nature of the patients.

Psychomotor performance and fitness to drive: the influence of psychiatric disease and its pharmacological treatment

Both psychiatric disorders and psychiatric drug treatments produce changes of psychomotor performance which can disturb and/or interfere with the ability to drive safely. We studied the influence of current psychiatric drug treatments on psychomotor functions and on driving performance of 77 consecutive psychiatric outpatients in two different clinical situations: at admission, when patients are destabilized and their mental disorders untreated, and after 6 weeks of pertinent psychotropic treatment. Fitness to drive and psychomotor performance were assessed using the electronic LNDETER 100 battery. Treatment effects on global functioning were assessed using the Clinical Global Impression of Change (CGIC) scale. One-way repeated measures analysis of variance and post hoc comparisons with the Bonferroni correction were performed. At the time of diagnosis, 90% of the patients failed to achieve scores sufficient to renew their driving licenses. After 6 weeks of adequate treatment, 83% improved their mental condition, and 17% either remained unchanged or deteriorated. Of those who improved, 25% had scores sufficiently high for them to drive legally, and the rest improved their performance from baseline assessment. Three of the four sub-tests were able to discriminate between patients with different clinical conditions. The study clearly suggests that medical treatment of psychiatric problems has a positive effect on driving tests.

Chemo brain - a psychotropic drug phenomenon?

The phenomenon of 'chemo brain' refers to a cluster of potentially long-lasting, cognitive deficiencies which are caused by systemic cancer treatments. While the oncology community has gradually acknowledged the existence of chemo brain as an unintended consequence of anti-neoplastic therapies, other fields of medicine have been less astute. Preliminary research evidence has suggested a role for many existing psychopharmaceuticals in fighting malignancies, based upon the capacity of these drugs to modify gene expression, cell turnover, and cell death (e.g., apoptosis). The author presents the hypothesis that the same mechanisms which suppress the growth and survival of cancer cells may pose similar hazards to non-diseased neurons, thereby inducing the cognitive changes which oncologists have come to associate with chemo brain. The article discusses the specific examples of valproic acid, clomipramine, and fluoxetine as treatments for solid tumors, primary brain tumors, and Burkitt's lymphoma, respectively. Clinicians, regardless of specialization, are encouraged to consider the potential reality of psychotropic chemo brain, in order to avoid or limit the use of medications which cause it, and in order to prioritize the delivery of rehabilitative strategies in an effort to mitigate or reverse its features.

Cognitive performance in depressed patients after chronic use of antidepressants

RATIONALE

Depressive disorders are conditions that often require continuous treatment, and it is therefore important to evaluate the consequences of prolonged administration. There are few studies assessing cognitive functions of depressed patients after long-term use of antidepressants.

OBJECTIVES

This study evaluated the cognitive performance of depressed patients treated with antidepressants for at least 6 months.

METHODS

Patients with major depression (DSM-IV) using imipramine for 2.4+/-0.6 years (mean+/-SE), clomipramine for 2.8+/-1.2 years, fluoxetine for 1.8+/-0.3 years and sertraline for 1.5+/-0.3 years were compared to matched controls (sex, age and educational level) without any psychiatric diagnosis. Memory evaluation consisted of episodic, implicit and working memory tests as well as metamemory assessment.

RESULTS

(a) Psychomotor performance of patients taking imipramine was worse than that of controls in inserting pins and a visual reaction time task; on the performance of tapping the difference from controls varied according to dose/weight for patients taking clomipramine and fluoxetine. (b) For memory tests, differences between patients taking sertraline and controls were observed in the number of digits and words recalled; the difference between patients and controls varied according to dose/weight on the number of familiar words correctly completed for patients taking clomipramine and on digit span backward for those taking sertraline. (c) Metamemory was worse in all patient groups irrespective of patients' clinical state.

CONCLUSIONS

The impairment in psychomotor and memory performances associated with these antidepressants seems to be of low intensity and of questionable clinical relevance.

Human implicit memory for irrelevant dimension values is similar to rats' incidental memory in simultaneous discrimination tasks

Participants completed a category-learning task in which they needed to discover which of three stimulus dimensions (shape, color or size) was relevant. After meeting a learning criterion (nine of 10 consecutive correct responses), participants continued making categorization choices and response latencies associated with these trials were examined. In both Experiments 1 and 2, people responded reliably faster when correct responses matched the previous responses with respect to irrelevant dimension values. Thus, they demonstrated a form of incidental short-term memory analogous to that we previously reported in studies of rats. In Experiment 2, participants' explicit memory for irrelevant dimension values was assessed after category learning was complete. The results indicated that people were unaware of the irrelevant dimension values encountered on trials preceding surprise probe trials. This indicates that memory for the irrelevant dimension values was implicit (i.e. unconscious). The findings are discussed with respect to both human and non-human studies of hippocampus-independent memory and implicit memory.

Increased neurogenesis and brain-derived neurotrophic factor in neurokinin-1 receptor gene knockout mice

It has previously been shown that chronic treatment with antidepressant drugs increases neurogenesis and levels of brain-derived neurotrophic factor in the hippocampus. These changes have been correlated with changes in learning and long-term potentiation and may contribute to the therapeutic efficacy of antidepressant drug treatment. Recently, antagonists at the neurokinin-1 receptor, the preferred receptor for the neuropeptide substance P, have been shown to have antidepressant activity. Mice with disruption of the neurokinin-1 receptor gene are remarkably similar both behaviourally and neurochemically to mice maintained chronically on antidepressant drugs. We demonstrate here that there is a significant elevation of neurogenesis but not cell survival in the hippocampus of neurokinin-1 receptor knockout mice. Neurogenesis can be increased in wild-type but not neurokinin-1 receptor knockout mice by chronic treatment with antidepressant drugs which preferentially target noradrenergic and serotonergic pathways. Hippocampal levels of brain-derived neurotrophic factor are also two-fold higher in neurokinin-1 receptor knockout mice, whereas cortical levels are similar. Finally, we examined hippocampus-dependent learning and memory but found no clear enhancement in neurokinin-1 receptor knockout mice. These data argue against a simple correlation between increased levels of neurogenesis or brain-derived neurotrophic factor and mnemonic processes in the absence of increased cell survival. They support the hypothesis that increased neurogenesis, perhaps accompanied by higher levels of brain-derived neurotrophic factor, may contribute to the efficacy of antidepressant drug therapy.

Effects of acute tryptophan depletion on executive function in healthy male volunteers

BACKGROUND

Neurocognitive impairment is frequently described in a number of psychiatric disorders and may be a direct consequence of serotonergic dysfunction. As impairments in executive functions are some of the most frequently described, the purpose of this study was to examine the performance of normal volunteers on a range of executive tasks following a transient reduction of central serotonin (5-HT) levels using the method of acute tryptophan depletion (ATD).

METHODS

Fifteen healthy male subjects participated in a within-subject, double-blind, counterbalanced crossover study. ATD was induced by ingestion of a 100 g amino-acid drink. Executive function was evaluated using the Wisconsin Card Sorting Test, Stroop, Verbal Fluency and Trail Making. Visual analogue scales were administered to assess mood.

RESULTS

Plasma free and total tryptophan concentrations were significantly reduced by the depleting drink (P < 0.001). ATD selectively improved motor speed/ attention on the Trails A test (P = 0.027), with no effect on subjective ratings of mood. Interaction effects between drink and the order of drink administration were observed on most neurocognitive tests.

CONCLUSIONS

The improvement in simple motor speed/ attention following ATD is in keeping with the ascribed role of 5-HT in the cortex, however performance on tests of executive function is not robustly altered. The presence of interaction effects on most tasks suggests that subtle changes may occur but are masked, possibly by simple learning effects, in the context of a crossover design. This has implications for the design of future studies, particularly those examining executive functions.