Abrupt and brief discontinuation of antidepressant treatment: effects on cognitive function and psychomotor performance

Continuous home cage monitoring of activity and sleep in mice during repeated paroxetine treatment and discontinuation

RATIONALE

Non-invasive home cage monitoring is emerging as a valuable tool to assess the effects of experimental interventions on mouse behaviour. A field in which these techniques may prove useful is the study of repeated selective serotonin reuptake inhibitor (SSRI) treatment and discontinuation. SSRI discontinuation syndrome is an under-researched condition that includes the emergence of sleep disturbances following treatment cessation.

OBJECTIVES

We used passive infrared (PIR) monitoring to investigate changes in activity, sleep, and circadian rhythms during repeated treatment with the SSRI paroxetine and its discontinuation in mice.

METHODS

Male mice received paroxetine (10 mg/kg/day, s.c.) for 12 days, then were swapped to saline injections for a 13 day discontinuation period and compared to mice that received saline injections throughout. Mice were continuously tracked using the Continuous Open Mouse Phenotyping of Activity and Sleep Status (COMPASS) system.

RESULTS

Repeated paroxetine treatment reduced activity and increased behaviourally-defined sleep in the dark phase. These effects recovered to saline-control levels within 24 h of paroxetine cessation, yet there was also evidence of a lengthening of sleep bouts in the dark phase for up to a week following discontinuation.

CONCLUSIONS

This study provides the first example of how continuous non-invasive home cage monitoring can be used to detect objective behavioural changes in activity and sleep during and after drug treatment in mice. These data suggest that effects of paroxetine administration reversed soon after its discontinuation but identified an emergent change in sleep bout duration, which could be used as a biomarker in future preclinical studies to prevent or minimise SSRI discontinuation symptoms.

Antidepressant Use During Hospice Patients' Final Months on Routine Home Care

Background: Antidepressants can be used to manage symptoms at the end of life, but the dying process can impact their use. Objectives: To examine the use of antidepressants during hospice patients' final months of home care. Methods: A retrospective case records review of 227 hospice patients in their last three months of care in a residential setting. Chart reviews were conducted of medication logs, hospice staff notes, and caregiver narratives to examine antidepressant use including types of medications prescribed and factors associated with medication maintenance. Results: Thirty percent of patients were prescribed at least 1 antidepressant for symptoms including depression, anxiety, pain, disturbances in sleep, and poor appetite. The majority (96.1%) of patients were not administered their antidepressant on the day of death, and more than half (61.8%) did not receive their antidepressant during their last 3 days of life. A quarter (25.5%) of patients on antidepressants did not receive medication 4-7 days prior to death while some (12.7%) went without their antidepressant for 8 or more days. Antidepressant use was discontinued by hospice staff or caregivers due to a variety of reasons including difficulty swallowing, minimal consciousness, confusion, nausea, or patient refusal. Conclusions: Antidepressants are prescribed to manage multiple symptoms at the end of life, but use is often disrupted during patients' final days. Tapering and other prescription adjustments may be warranted to avoid risk of antidepressant discontinuation syndrome (ADS).

Estimating Risk of Antidepressant Withdrawal from a Review of Published Data

Adaptation of the brain to the presence of a drug predicts withdrawal on cessation. The outcome of adaptation is often referred to as 'physical dependence' in pharmacology, as distinct from addiction, although these terms have unfortunately become conflated in some diagnostic guides. Physical dependence to antidepressants may occur in some patients, consistent with the fact that some patients experience withdrawal effects from these medications. It is thought that longer duration of use, higher dose and specific antidepressants affect the risk of antidepressant withdrawal effects as they might cause greater adaptation of the brain. We searched PubMed for relevant systematic reviews and other relevant analyses to summarise existing data on determinants of antidepressant withdrawal incidence, severity and duration. Overall, data were limited. From survey data, increased duration of use was associated with an increased incidence and severity of withdrawal effects, consistent with some evidence from data provided by drug manufacturers. Duration of use may be related to duration of withdrawal effects but data are heterogenous and sparse. Serotonin and noradrenaline reuptake inhibitors and paroxetine are associated with higher risks than other antidepressants, though data for some antidepressants are lacking. Higher doses of antidepressant has some weak association with an increased risk of withdrawal, with some ceiling effects, perhaps reflecting receptor occupancy relationships. Past experience of withdrawal effects is known to predict future risk. Based on these data, we outline a preliminary rubric for determining the risk of withdrawal symptoms for a particular patient, which may have relevance for determining tapering rates. Given the limited scope of the current research, future research should aim to clarify prediction of antidepressant withdrawal risk, especially by examining the risk of withdrawal in long-term users of medication, as well as the severity and duration of effects, to improve the preliminary tool for predictive purposes. Further research into the precise adaptations in long-term antidepressant use may improve the ability to predict withdrawal effects for a particular patient.

Amitriptyline Improves Cognitive and Neuronal Function in a Rat Model that Mimics Dementia with Lewy Bodies

Dementia with Lewy bodies (DLB), a highly prevalent neurodegenerative disorder, causes motor and cognitive deficits. The main pathophysiologies of DLB are glutamate excitotoxicity and accumulation of Lewy bodies comprising α-synuclein (α-syn) and β-amyloid (Aβ). Amitriptyline (AMI) promotes expression of glutamate transporter-1 and glutamate reuptake. In this study, we measured the effects of AMI on behavioral and neuronal function in a DLB rat model. We used rivastigmine (RIVA) as a positive control. To establish the DLB rat model, male Wistar rats were stereotaxically injected with recombinant adenoassociated viral vector with the SNCA gene (10μg/10μL) and Aβ (5μg/2.5μL) into the left ventricle and prefrontal cortex, respectively. AMI (10mg/kg/day, i.p.), RIVA (2mg/kg/day, i.p.), or saline was injected intraperitoneally after surgery. From the 29^th day, behavioral tests were performed to evaluate the motor and cognitive functions of the rats. Immunohistochemical staining was used to assess neuronal changes. We measured the α-syn level, number of newborn cells, and neuronal density in the hippocampus and in the nigrostriatal dopaminergic system. The DLB group exhibited deficit in object recognition. Both the AMI and RIVA treatments reversed these deficits. Histologically, the DLB rats exhibited cell loss in the substantia nigra pars compacta and in the hippocampal CA1 area. AMI reduced this cell loss, but RIVA did not. In addition, the DLB rats exhibited a lower number of newborn cells and higher α-syn levels in the dentate gyrus (DG). AMI did not affect α-syn accumulation but recovered neurogenesis in the DG of the rats, whereas RIVA reversed the α-syn accumulation but did not affect neurogenesis in the rats. We suggest that AMI may have potential for use in the treatment of DLB.

An Oppositional Tolerance Account for Potential Cognitive Deficits Caused by the Discontinuation of Antidepressant Drugs

Depression is the leading cause of disability worldwide, making antidepressant drugs the most used psychiatric drugs in the USA. Withdrawal effects and rebound symptoms frequently occur after the reduction and/or discontinuation of these drugs. Although these phenomena have been investigated with respect to the clinical symptomatology, no studies have systematically investigated the effects of withdrawal/rebound on general cognition. We present a novel framework based on the idea of allostatic adaptation, which allows to predict how different antidepressants likely impair different cognitive processes as a result of withdrawal and rebound effects. This framework relies on the assumptions that the type of cognitive impairments evoked by an antidepressant is determined by the targeted neurotransmitter systems, while the severity of deficits depends on its half-life. Our model predicts that the severity of detrimental cognitive withdrawal and rebound effects increases with a shorter half-life of the discontinued antidepressant drug. It further proposes drug-specific effects: antidepressants mainly targeting serotonin should primarily impair aversive and emotional processing, those targeting norepinephrine should impair the processing of alerting signals, those targeting dopamine should impair motivational processes and reward processing, and those targeting acetylcholine should impair spatial learning and memory. We hope that this framework will motivate further research to better understand and explain cognitive changes as a consequence of antidepressant discontinuation.

Antidepressant Withdrawal and Rebound Phenomena

BACKGROUND

Antidepressants are among the most commonly prescribed drugs worldwide. They are often discontinued, frequently without the knowledge of the prescribing physician. It is, therefore, important for physicians to be aware of the withdrawal and rebound phenomena that may arise, in order to prevent these phenomena, treat them when necessary, and counsel patients appropriately.

METHODS

This review is based on a comprehensive, structured literature search on antidepressant withdrawal phenomena that we carried out in the CENTRAL, PubMed (Medline), and Embase databases. We classified the relevant publications and reports by their methodological quality.

RESULTS

Out of a total of 2287 hits, there were 40 controlled trials, 38 cohort studies and retrospective analyses, and 271 case reports that met the inclusion criteria. Withdrawal manifestations are usually mild and self-limiting; common ones include dizziness, headache, sleep disturbances, and mood swings. More serious or pro- longed manifestations rarely arise. There is an increased risk with MAO inhibitors, tricyclic antidepressants, venlafaxine, and paroxetine; on the other hand, for agome- latine and fluoxetine, abrupt discontinuation seems to be unproblematic. There is also some evidence of rebound phenomena, i.e., of higher relapse rates or especially severe relapses of depression after the discontinuation of an anti- depressant.

CONCLUSION

A robust evidence base now indicates that there can be acute with- drawal phenomena when antidepressants are discontinued. Putative rebound phenomena have not been adequately studied to date. It is recommended that antidepressants should be tapered off over a period of more than four weeks.

A systematic review into the incidence, severity and duration of antidepressant withdrawal effects: Are guidelines evidence-based?

INTRODUCTION

The U.K.'s current National Institute for Health and Care Excellence and the American Psychiatric Association's depression guidelines state that withdrawal reactions from antidepressants are 'self-limiting' (i.e. typically resolving between 1 and 2weeks). This systematic review assesses that claim.

METHODS

A systematic literature review was undertaken to ascertain the incidence, severity and duration of antidepressant withdrawal reactions. We identified 24 relevant studies, with diverse methodologies and sample sizes.

RESULTS

Withdrawal incidence rates from 14 studies ranged from 27% to 86% with a weighted average of 56%. Four large studies of severity produced a weighted average of 46% of those experiencing antidepressant withdrawal effects endorsing the most extreme severity rating on offer. Seven of the ten very diverse studies providing data on duration contradict the U.K. and U.S.A. withdrawal guidelines in that they found that a significant proportion of people who experience withdrawal do so for more than two weeks, and that it is not uncommon for people to experience withdrawal for several months. The findings of the only four studies calculating mean duration were, for quite heterogeneous populations, 5days, 10days, 43days and 79weeks.

CONCLUSIONS

We recommend that U.K. and U.S.A. guidelines on antidepressant withdrawal be urgently updated as they are clearly at variance with the evidence on the incidence, severity and duration of antidepressant withdrawal, and are probably leading to the widespread misdiagnosing of withdrawal, the consequent lengthening of antidepressant use, much unnecessary antidepressant prescribing and higher rates of antidepressant prescriptions overall. We also recommend that prescribers fully inform patients about the possibility of withdrawal effects.

Tapering of SSRI treatment to mitigate withdrawal symptoms

All classes of drug that are prescribed to treat depression are associated with withdrawal syndromes. SSRI withdrawal syndrome occurs often and can be severe, and might compel patients to recommence their medication. Although the withdrawal syndrome can be differentiated from recurrence of the underlying disorder, it might also be mistaken for recurrence, leading to long-term unnecessary medication. Guidelines recommend short tapers, of between 2 weeks and 4 weeks, down to therapeutic minimum doses, or half-minimum doses, before complete cessation. Studies have shown that these tapers show minimal benefits over abrupt discontinuation, and are often not tolerated by patients. Tapers over a period of months and down to doses much lower than minimum therapeutic doses have shown greater success in reducing withdrawal symptoms. Other types of medication associated with withdrawal, such as benzodiazepenes, are tapered to reduce their biological effect at receptors by fixed amounts to minimise withdrawal symptoms. These dose reductions are done with exponential tapering programmes that reach very small doses. This method could have relevance for tapering of SSRIs. We examined the PET imaging data of serotonin transporter occupancy by SSRIs and found that hyperbolically reducing doses of SSRIs reduces their effect on serotonin transporter inhibition in a linear manner. We therefore suggest that SSRIs should be tapered hyperbolically and slowly to doses much lower than those of therapeutic minimums, in line with tapering regimens for other medications associated with withdrawal symptoms. Withdrawal symptoms will then be minimised.

The association between antidepressant use and deaths from road traffic accidents: a case-crossover study

PURPOSE

Antidepressants are some of the most commonly used psychiatric medications, but little information is available about the effects of antidepressant treatment on the risk of traffic accidents across classes of antidepressants or associated with each substance individually. To investigate the relationship between exposure to antidepressants and risk of fatality in road traffic accidents.

METHODS

We used a Korean national road traffic authority database linked with a national health insurance database between January 1, 2010 and December 31, 2014 and applied a case-crossover design. The study subjects were drivers in South Korea who died from traffic accidents and who had prescriptions for antidepressants within 1 year prior to the date of the accident. We compared the status of prescription for antidepressants with the hazard period and four matched control periods using conditional logistic regression, adjusting for other drug use. The trends of antidepressant utilization were described in terms of the number of prescriptions. A case-case-time-control design was applied to drugs with an increasing trend in use and a significant case-crossover odds ratio (OR).

RESULTS

A total of 1250 antidepressant-using drivers were included, and an increased risk was observed during the 30-day hazard period (adjusted OR 1.30; 95% CI 1.03-1.63). Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) showed significant risks, but tricyclic antidepressants did not. However, the associations of all antidepressants, SSRIs, SNRIs, escitalopram, and duloxetine did not remain significant after adjusting for trends in utilization. Paroxetine and milnacipran were associated with increased risks, with no obvious increase in their utilization, but the possibility of confounding by indication could have affected the results for milnacipran.

CONCLUSION

Considering the trends of antidepressant prescription and utilization, the use of paroxetine increased the risk of fatal traffic accidents.

Cognitive Dysfunction in Major Depressive Disorder: Assessment, Impact, and Management

Cognitive dysfunction is increasingly being recognized as an important clinical dimension in major depressive disorder. This review summarizes the existing data on the epidemiology, assessment, and treatment of cognitive dysfunction among nonelderly adults with the disorder. Overall, cognitive dysfunction is prevalent, persists through periods of symptom remission, and may be independently associated with functional outcomes. However, although the evidence increasingly suggests that clinicians should be heedful of their patients' cognitive functioning, there is as yet no consensus on how best to monitor cognition clinically. In addition, although most studies have reported improved cognition with antidepressant medications, psychotherapy, and neuromodulation, the clinical significance of these improvements is unclear, and high-level evidence to guide decision making is limited. Nonetheless, given the important functional implications, clinicians should assess and monitor cognition and optimize both medication and psychological treatments to mitigate cognitive dysfunction among patients with major depressive disorder.

Withdrawal Symptoms after Selective Serotonin Reuptake Inhibitor Discontinuation: A Systematic Review

Background: Selective serotonin reuptake inhibitors (SSRI) are widely used in medical practice. They have been associated with a broad range of symptoms, whose clinical meaning has not been fully appreciated. Methods: The PRISMA guidelines were followed to conduct a systematic review of the literature. Titles, abstracts, and topics were searched using the following terms: 'withdrawal symptoms' OR 'withdrawal syndrome' OR 'discontinuation syndrome' OR 'discontinuation symptoms', AND 'SSRI' OR 'serotonin' OR 'antidepressant' OR 'paroxetine' OR 'fluoxetine' OR 'sertraline' OR 'fluvoxamine' OR 'citalopram' OR 'escitalopram'. The electronic research literature databases included CINAHL, the Cochrane Library, PubMed and Web-of-Science from inception of each database to July 2014. Results: There were 15 randomized controlled studies, 4 open trials, 4 retrospective investigations, and 38 case reports. The prevalence of the syndrome was variable, and its estimation was hindered by a lack of case identification in many studies. Symptoms typically occur within a few days from drug discontinuation and last a few weeks, also with gradual tapering. However, many variations are possible, including late onset and/or longer persistence of disturbances. Symptoms may be easily misidentified as signs of impending relapse. Conclusions: Clinicians need to add SSRI to the list of drugs potentially inducing withdrawal symptoms upon discontinuation, together with benzodiazepines, barbiturates, and other psychotropic drugs. The term 'discontinuation syndrome' that is currently used minimizes the potential vulnerabilities induced by SSRI and should be replaced by 'withdrawal syndrome'. © 2015 S. Karger AG, Basel.

The psychoactive effects of psychiatric medication: the elephant in the room

The psychoactive effects of psychiatric medications have been obscured by the presumption that these medications have disease-specific actions. Exploiting the parallels with the psychoactive effects and uses of recreational substances helps to highlight the psychoactive properties of psychiatric medications and their impact on people with psychiatric problems. We discuss how psychoactive effects produced by different drugs prescribed in psychiatric practice might modify various disturbing and distressing symptoms, and we also consider the costs of these psychoactive effects on the mental well-being of the user. We examine the issue of dependence, and the need for support for people wishing to withdraw from psychiatric medication. We consider how the reality of psychoactive effects undermines the idea that psychiatric drugs work by targeting underlying disease processes, since psychoactive effects can themselves directly modify mental and behavioral symptoms and thus affect the results of placebo-controlled trials. These effects and their impact also raise questions about the validity and importance of modern diagnosis systems. Extensive research is needed to clarify the range of acute and longer-term mental, behavioral, and physical effects induced by psychiatric drugs, both during and after consumption and withdrawal, to enable users and prescribers to exploit their psychoactive effects judiciously in a safe and more informed manner.

Selective serotonin reuptake inhibitor antidepressant treatment discontinuation syndrome: a review of the clinical evidence and the possible mechanisms involved

Besides demonstrated efficacy, selective serotonin reuptake inhibitors (SSRIs) hold other advantages over earlier antidepressants such as greater tolerability and a wider range of clinical applications. However, there is a growing body of clinical evidence which suggests that SSRIs could, in some cases, be associated with a withdrawal reaction upon cessation of regular use. In addition to sensory and gastrointestinal-related symptoms, the somatic symptoms of the SSRI discontinuation syndrome include dizziness, lethargy, and sleep disturbances. Psychological symptoms have also been documented, usually developing within 1–7 days following SSRI discontinuation. The characteristics of the discontinuation syndrome have been linked to the half-life of a given SSRI, with a greater number of reports emerging from paroxetine compared to other SSRIs. However, many aspects of the neurobiology of the SSRI discontinuation syndrome (or SSRI withdrawal syndrome) remain unresolved. Following a comprehensive overview of the clinical evidence, we will discuss the underlying pathophysiology of the SSRI discontinuation syndrome and comment on the use of animal models to better understand this condition.

Citalopram versus other anti-depressive agents for depression

BACKGROUND

Recent US and UK clinical practice guidelines recommend that second-generation antidepressants should be considered amongst the best first-line options when drug therapy is indicated for a depressive episode. Systematic reviews have already highlighted some differences in efficacy between second-generation antidepressants. Citalopram, one of the first selective serotonin reuptake inhibitors (SSRI) introduced in the market, is one of these antidepressant drugs that clinicians use for routine depression care.

OBJECTIVES

To assess the evidence for the efficacy, acceptability and tolerability of citalopram in comparison with tricyclics, heterocyclics, other SSRIs and other conventional and non-conventional antidepressants in the acute-phase treatment of major depression.

SEARCH METHODS

We searched The Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register and the Cochrane Central Register of Controlled Trials up to February 2012. No language restriction was applied. We contacted pharmaceutical companies and experts in this field for supplemental data.

SELECTION CRITERIA

Randomised controlled trials allocating patients with major depression to citalopram versus any other antidepressants.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data. Information extracted included study characteristics, participant characteristics, intervention details and outcome measures in terms of efficacy (the number of patients who responded or remitted), patient acceptability (the number of patients who failed to complete the study) and tolerability (side-effects).

MAIN RESULTS

Thirty-seven trials compared citalopram with other antidepressants (such as tricyclics, heterocyclics, SSRIs and other antidepressants, either conventional ones, such as mirtazapine, venlafaxine and reboxetine, or non-conventional, like hypericum). Citalopram was shown to be significantly less effective than escitalopram in achieving acute response (odds ratio (OR) 1.47, 95% confidence interval (CI) 1.08 to 2.02), but more effective than paroxetine (OR 0.65, 95% CI 0.44 to 0.96) and reboxetine (OR 0.63, 95% CI 0.43 to 0.91). Significantly fewer patients allocated to citalopram withdrew from trials due to adverse events compared with patients allocated to tricyclics (OR 0.54, 95% CI 0.38 to 0.78) and fewer patients allocated to citalopram reported at least one side effect than reboxetine or venlafaxine (OR 0.64, 95% CI 0.42 to 0.97 and OR 0.46, 95% CI 0.24 to 0.88, respectively).

AUTHORS' CONCLUSIONS

Some statistically significant differences between citalopram and other antidepressants for the acute phase treatment of major depression were found in terms of efficacy, tolerability and acceptability. Citalopram was more efficacious than paroxetine and reboxetine and more acceptable than tricyclics, reboxetine and venlafaxine, however, it seemed to be less efficacious than escitalopram. As with most systematic reviews in psychopharmacology, the potential for overestimation of treatment effect due to sponsorship bias and publication bias should be borne in mind when interpreting review findings. Economic analyses were not reported in the included studies, however, cost effectiveness information is needed in the field of antidepressant trials.

A case report of onset of tinnitus following discontinuation of antidepressant and a review of the literature

This case report describes a 46-year-old woman with long-standing episodic severe depression (ICD-10 code F33) who discontinued venlafaxine over a 4-week taper after taking the antidepressant for 8 years. Severe discontinuation syndrome was experienced. Panic and relapse of depression occurred 2 months after achieving discontinuation, and the development of tinnitus took place concurrently to the discontinuation. The experience of the tinnitus as a side effect of discontinuation is different from cases reported in the literature in which the tinnitus was experienced when the antidepressant was started and ceased when the antidepressant was stopped. Here, the patient experienced the tinnitus as a discontinuation symptom, and it persisted even after the antidepressant was reintroduced. A review of the literature on antidepressant discontinuation syndrome is also provided.

Citalopram versus desipramine in treatment resistant depression: effect of continuation or switching strategies: a randomized open study

OBJECTIVES. Evidence in favour of switching between selective serotonin reuptake inhibitor (SSRI) and tricyclic (TCA) antidepressants in treatment resistant depression has been tested in a few studies only, consequently a prospective study was undertaken to evaluate the impact of switching strategies. METHODS. One hundred eighty-nine patients who failed to respond to a previous antidepressant were randomised to four arms: firstly they received citalopram or desipramine for a 4-week period; secondly, those who failed to respond were treated for a further 4-week period with the same antidepressant (citalopram-citalopram and desipramine-desipramine arms) or switched to the alternate one (citalopram-desipramine and desipramine-citalopram arms). RESULTS. There was no difference in the first 4-week phase between patients receiving citalopram versus desipramine in Hamilton Rating Scale for Depression (HRSD), Montgomery-Asberg Depression Rating Scale (MADRS), and Clinical Global Impression (CGI) scores. In the second 4-week phase remitter rates were higher among non-switched patients (P = 0.04). Moreover, considering HRSD and MADRS, switched patients reported significantly higher scores (P ≤ 0.02 for both scales at each time-point). CONCLUSIONS. This study supports the thesis that switching from an SSRI to a TCA (and vice versa) in non-responders to a 4-week trial of an SSRI/TCA is not associated with improved response. The result goes in the opposite direction to that predicted by current guidelines.

A systematic, updated review on the antidepressant agomelatine focusing on its melatonergic modulation

Objective:

To present an updated, comprehensive review on clinical and pre-clinical studies on agomelatine.

Method:

A MEDLINE, Psycinfo and Web of Science search (1966-May 2009) was performed using the following keywords: agomelatine, melatonin, S20098, efficacy, safety, adverse effect, pharmacokinetic, pharmacodynamic, major depressive disorder, bipolar disorder, Seasonal Affective Disorder (SAD), Alzheimer, ADHD, Generalized Anxiety Disorder (GAD), Panic Disorder (PD), Obsessive-Compulsive Disorder (OCD), anxiety disorders and mood disorder.

Study collection and data extraction:

All articles in English identified by the data sources were evaluated. Randomized, controlled clinical trials involving humans were prioritized in the review. The physiological bases of melatonergic transmission were also examined to deepen the clinical comprehension of agomelatine’ melatonergic modulation.

Data synthesis:

Agomelatine, a melatonergic analogue drug acting as MT₁/MT₂ agonist and 5-HT_2C antagonist, has been reported to be an effective antidepressant therapy.

Conclusions:

Although a bias in properly assessing the “sleep core” of depression may still exist with current screening instruments, therefore making difficult to compare agomelatine’ efficacy to other antidepressant ones, comparative studies showed agomelatine to be an intriguing option for depression and, potentially, for other therapeutic targets as well.

Hallucination induced by paroxetine discontinuation in patients with major depressive disorders

Discontinuation symptoms can follow the stoppage of almost all classes of antidepressants, including selective serotonin reuptake inhibitors. We report two cases suffering from visual and auditory hallucinations: Case 1 abruptly stopped taking paroxetine (20 mg/day), and Case 2 discontinued paroxetine after reducing the dose from 20 mg/day to 10 mg/day for 5 months. Both cases experienced visual and auditory hallucinations in addition to dizziness, headache, insomnia, and nausea a couple of days after paroxetine discontinuation. These observations suggest that hallucinations are a part of the discontinuation syndrome that results from paroxetine discontinuation. Physicians should be aware of this symptom.

Effects of the serotonin 1A, 2A, 2C, 3A, and 3B and serotonin transporter gene polymorphisms on the occurrence of paroxetine discontinuation syndrome

Paroxetine discontinuation symptoms can at times be severe enough to reduce the quality of life. However, it is currently not possible to predict the occurrence of discontinuation syndrome before the initiation or discontinuation of paroxetine treatment. In this study, we investigated the effects of genetic polymorphisms in the serotonin 1A, 2A, 2C, 3A, and 3B receptor, the serotonin transporter, and the cytochrome P450 2D6 (CYP2D6) genes on the occurrence of paroxetine discontinuation syndrome. A consecutive series of 56 Japanese patients who had a diagnosis of major depressive or anxiety disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, were treated with paroxetine. Paroxetine discontinuation syndrome was found in 35.7% of the patients by direct interview. Patients who stopped taking paroxetine abruptly experienced paroxetine discontinuation syndrome significantly more often than patients who had a tapering off of the dosage of medication. Patients who had the -1019C allele experienced paroxetine discontinuation syndrome more frequently than patients who had the -1019G homozygote (nominal P = 0.0423) of the serotonin 1A receptor gene. However, this result did not remain significant after the Bonferroni correction for multiple comparisons. The findings suggest that the abrupt stoppage of medication is a major risk factor for the occurrence of paroxetine discontinuation syndrome and that C(-1019)G polymorphism of the serotonin 1A receptor gene may be related to the occurrence of the syndrome.

Agomelatine: innovative pharmacological approach in depression

Currently available antidepressant agents such as tricyclic antidepressants (TCAs) act primarily through monoaminergic systems in the brain, and have proved to be suboptimal for the management of major depressive disorder (MDD). Such agents are also active at non-target receptor sites, contributing to the development of often serious adverse events. Even the newer selective serotonin reuptake inhibitors (SSRIs), which also act through monoaminergic systems, have suboptimal antidepressant efficacy, and the adverse events that do occur often negatively influence adherence. Although the pathophysiology of depression is not completely understood, it is increasingly recognized that monoamine deficiency/disruption is not the only pathway involved. Recognition that circadian rhythm desynchronization also plays a key role in mood disorders has led to the development of agomelatine, which is endowed with a novel mechanism of action distinct from that of currently available antidepressants. Agomelatine is an agonist of the melatonergic MT(1) and MT(2) receptors, as well as a 5-HT(2C) receptor antagonist. The antidepressant activity of agomelatine is proposed to stem from the synergy between these sets of receptors, which are key components of the circadian timing system. Agomelatine has shown antidepressant-like activity in a number of animal models of depression, such as the learned helplessness model, the chronic mild stress model, the forced swim test and the chronic psychosocial stress test. Moreover, agomelatine has been found to restore normal circadian rhythms in animal models of a disrupted circadian system, and has proved beneficial in an animal model of delayed sleep phase syndrome. Likewise, it has been shown to improve disturbed sleep-wake rhythms in depressed patients. Moreover, current pharmacological and clinical data strongly support the use of agomelatine in the management of MDD.

Discontinuation symptoms and taper/poststudy-emergent adverse events with desvenlafaxine treatment for major depressive disorder

The objective of this study was to assess discontinuation symptoms with desvenlafaxine (administered as desvenlafaxine succinate) treatment for major depressive disorder. Data were analyzed from nine 8-week, double-blind (DB), placebo-controlled studies of desvenlafaxine (50, 100, 200, or 400 mg/day; placebo, n = 319; desvenlafaxine, n = 578) and a relapse-prevention study [12-week, open-label (OL) 200 or 400 mg/day desvenlafaxine (n = 373); 6-month DB placebo (n = 73) or desvenlafaxine (n = 118)]. Rates of taper/poststudy-emergent adverse events were summarized. Discontinuation-Emergent Signs and Symptoms (DESS) checklist scores were analyzed in treatment completers at the end of OL and DB treatment. The most common (> or = 5%) taper/poststudy-emergent adverse events among desvenlafaxine patients were dizziness, nausea, headache, irritability, diarrhea, anxiety, abnormal dreams, fatigue, and hyperhidrosis. In the short-term studies, the highest DESS scores observed for desvenlafaxine groups occurred at first assessment after discontinuation of all active treatment (1.9-5.7). Desvenlafaxine 50- and 100-mg/day groups had significantly increased scores versus placebo (P values < or = 0.028). DESS scores increased significantly for patients discontinuing 12-week, OL desvenlafaxine 200 and 400 mg/day doses compared with those continuing desvenlafaxine (P values < or = 0.022). After the 6-month DB phase, DESS scores increased significantly compared with placebo for patients discontinuing 400 mg/day only (P = 0.029). In conclusion, cessation of desvenlafaxine use is associated with discontinuation symptoms after both short-term and long-term treatment.

Limitations of current medical treatments for depression: disturbed circadian rhythms as a possible therapeutic target

The proportion of diagnosed depressives prescribed antidepressants has increased markedly over the last 20 years, mainly following the introduction of the selective serotonin reuptake inhibitors. However, currently available antidepressants have notable limitations, relating to their only moderate efficacy relative to placebo, relatively slow onset of action, possible withdrawal symptoms, and problems of compliance. Sleep disturbances are often used to identify newly presenting depressive patients, and may be part of a more general alteration of bodily rhythms. There are links between pharmacological treatments and circadian rhythms in depression, which might represent another, new option for the development of a therapeutic approach to depression treatment. Many antidepressants affect sleep, some are sedative, and others have been used specifically in severely insomniac depressives. Disturbances in circadian rhythms may be an integral part of depressive mechanisms, and normalising them via an innovative mechanism of antidepressant action may be a fruitful avenue in the search for improved antidepressant agents.

Efficacy of agomelatine, a MT1/MT2 receptor agonist with 5-HT2C antagonistic properties, in major depressive disorder

Current antidepressants used in major depressive disorder (MDD) are still not efficacious enough for many patients due to high levels of treatment resistance and bothersome side-effects. Using a novel blinding method (interactive voice response system), this flexible-dosing study examined the effects of therapeutic doses of agomelatine, a new approach to depressive therapy offering potent melatonergic MT1/MT2 receptor agonism with 5-HT2C receptor antagonist properties, in patients with moderate-to-severe MDD. This 6-wk, double-blind, parallel-group study randomized 238 patients to 25 mg/d agomelatine (with dose adjustment at 2 wk to 50 mg/d in patients with insufficient improvement) or placebo. Depression severity was assessed using the Hamilton Depression Rating Scale (HAMD) and the Clinical Global Impression (CGI) scale. Agomelatine was significantly more efficacious than placebo, with an agomelatine-placebo difference of 3.44 (p<0.001) using the HAMD final total score. Compared with placebo, agomelatine also had a significant positive impact on CGI - Improvement (treatment difference=0.45) and CGI - Severity (treatment difference=0.50) (both p=0.006), response rate (54.3% vs. 35.5% with placebo, p<0.05) and time to first response (p=0.008). Similar results were seen in patients with the most severe MDD. Depressed mood and sleep items of the HAMD were also significantly improved with agomelatine, which was well tolerated with a safety profile similar to placebo at both doses. This study confirms that agomelatine is effective in treating major depression, including the most severely depressed patients, with a good safety and tolerability profile, therefore providing physicians with an effective pharmacological approach to antidepressant therapy.

Potential Medical and Surgical Complications of Serotonergic Antidepressant Medications

Serotonergic antidepressants are the most widely used group of antidepressant medications. Although generally considered to have a favorable adverse-effect profile, serotonergic antidepressants are associated with potentially dangerous medical complications, some of which have only recently become apparent to patients and clinicians. This article reviews the association of serotonergic antidepressants and the following medical complications: syndrome of inappropriate antidiuretic hormone secretion, bleeding, serotonin syndrome, serotonin-discontinuation syndrome, and adverse pregnancy and neonatal effects. Physicians need to remain aware of these potential medical complications and integrate this information into their clinical decision-making, informed-consent process, baseline assessment, and follow-up monitoring.

Pharmacotherapy of Mood Disorders and Treatment Discontinuation

Depression is the most frequent and costly problem in primary care, where most of these patients are seen and treated. In many countries, the public regard antidepressant drugs as 'addictive', partly because of the withdrawal symptoms that can occur when they are discontinued. Indeed, discontinuation (withdrawal) symptoms can follow the stoppage of almost all classes of antidepressants, including selective serotonin receptor inhibitors (SSRIs). This is important because they are widely regarded as drugs of choice for both depression and the anxiety disorders. But is this true withdrawal or merely rebound? The antidepressant discontinuation syndrome is characterised by the time-locked emergence of new, clearly defined and quantifiable signs and symptoms that ensue on stopping or reducing the dose of an antidepressant. Thereby, it meets the criteria for a withdrawal syndrome. The symptoms are not usually severe or protracted. SSRIs vary in their propensity to be associated with a discontinuation syndrome: paroxetine appears to be the most likely. Patients should be warned of the possibility of developing such a reaction, but reassured that it is usually mild and self limiting. Tapering the dose, if practicable, is worthwhile. In severe cases, temporary reinstatement of the SSRI and slower tapering may be necessary. Escalation of antidepressant dosage, or 'street abuse', is rare with antidepressants. The use of antidepressants is generally beneficial, and efforts should be made to optimise our current use of these drugs as well as encouraging the development of newer, better and innovative compounds. To this end, physicians should educate themselves and the public about discontinuation and withdrawal, so that these clinical features can be put in a realistic context.

A double-blind, randomized, parallel-group, flexible-dose study to evaluate the tolerability, efficacy and effects of treatment discontinuation with escitalopram and paroxetine in patients with major depressive disorder

This multinational, randomized, double-blind, flexible-dose study evaluated the short- and long-term antidepressant tolerability and efficacy of escitalopram and paroxetine. Tolerability was assessed by monitoring adverse events throughout the study, and discontinuation events during brief treatment interruption and tapered withdrawal. Discontinuation-emergent effects were evaluated in two separate double-blind periods. First, to mimic the consequences of non-compliance, patients were randomized to one of two treatment interruption periods (placebo-substitution for 3-5 days). Second, patients were randomized to a 1-2-week tapered withdrawal period randomly scheduled between weeks 28 and 31. The pre-specified primary efficacy endpoint was the mean change from baseline in total Montgomery-Asberg Depression Rating Scale (MADRS) score at week 8, using the principle of last observation carried forward. A total of 323 patients entered 8 weeks of double-blind treatment and received at least one flexible dose of escitalopram (10-20 mg/day) or paroxetine (20-40 mg/day). Patients who demonstrated evidence of a significant clinical improvement (Clinical Global Impression-Improvement of 1 or 2) at week 8 entered a 19-week, double-blind maintenance period during which they were treated with the same dose they received at week 8, followed by a 1-2-week tapered withdrawal period. A total of 89 patients (28%) withdrew during the study; significantly (P<0.01) more patients withdrew from the paroxetine group (34%) than from the escitalopram group (21%), and significantly (P<0.05) more paroxetine patients withdrew due to lack of efficacy. The mean MADRS total score improved for both treatment groups from baseline to week 8, with no statistical difference between groups. In severely depressed patients (baseline MADRS total score >or=30), escitalopram was superior (P<0.05) to paroxetine at week 27 (end of maintenance treatment). There was a high prevalence of sexual dysfunction at baseline: the mean Arizona Sexual Experience Scale (ASEX) score was approximately 20 points in both treatment groups. Mean total ASEX scores increased slightly above baseline values during the acute period and declined slightly below baseline values towards the end of the maintenance period. During taper and cessation of treatment, patients in the paroxetine group demonstrated significantly more discontinuation symptoms relative to escitalopram based on the Discontinuation Emergent Signs and Symptoms scores.

Tolerability and safety of fluvoxamine and other antidepressants

Selective serotonin [5-hydroxytryptamine (5-HT)] reuptake inhibitors (SSRIs) and the 5-HT noradrenaline reuptake inhibitor, venlafaxine, are mainstays in treatment for depression. The highly specific actions of SSRIs of enhancing serotonergic neurotransmission appears to explain their benefit, while lack of direct actions on other neurotransmitter systems is responsible for their superior safety profile compared with tricyclic antidepressants. Although SSRIs (and venlafaxine) have similar adverse effects, certain differences are emerging. Fluvoxamine may have fewer effects on sexual dysfunction and sleep pattern. SSRIs have a cardiovascular safety profile superior to that of tricyclic antidepressants for patients with cardiovascular disease; fluvoxamine is safe in patients with cardiovascular disease and in the elderly. A discontinuation syndrome may develop upon abrupt SSRI cessation. SSRIs are more tolerable than tricyclic antidepressants in overdose, and there is no conclusive evidence to suggest that they are associated with an increased risk of suicide. Although the literature suggests that there are no clinically significant differences in efficacy amongst SSRIs, treatment decisions need to be based on considerations such as patient acceptability, response history and toxicity.

Efficacy and tolerance profile of agomelatine and practical use in depressed patients

Agomelatine is a new agent with a unique pharmacological profile, as the first melatonergic antidepressant. Its antidepressant efficacy has been demonstrated in the treatment of major depressive disorder (MDD) at a dose of 25 mg/day. Expectations from antidepressant therapies now go beyond efficacy alone, to include advantages in tolerability and safety. Due to its pharmacological profile, agomelatine does not induce the side-effects typical of other therapies, such as selective serotonin reuptake inhibitors (i.e. gastrointestinal disorders, weight gain, serotonergic syndrome and insomnia). Moreover, a placebo-controlled trial in MDD comparing the effects of agomelatine and venlafaxine on sexual dysfunction (another significant side-effect with current antidepressant medications) indicated the very favourable profile of agomelatine; in the same study, there was similar antidepressant efficacy in the same two groups. A double-blind, placebo-controlled trial investigating the effect of abrupt cessation of treatment demonstrated the absence of discontinuation symptoms with agomelatine, which was in contrast with the results observed with paroxetine. The ability of an antidepressant to relieve sleep complaints with no sedative effects is a key advantage because sleep complaints are a major presenting feature of depression. Again due to its unique pharmacological profile, agomelatine has been shown to positively influence disturbed circadian rhythms in depressed patients by significantly improving all phases of disturbed sleep and the overall quality of sleep, with a favourable impact on daytime alertness. In conclusion, experience with agomelatine across a range of clinical studies suggests that this compound offers a novel approach to the treatment of depression combining efficacy, even in severe depression, with an extremely favourable side-effect profile and sleep regulation. These properties give agomelatine a definite clinical advantage in the treatment of depression.

Why do we need new and better antidepressants?

The range of available antidepressants is reviewed in relation to mechanisms of action and the evidence of efficacy in general and efficacy in severe depression in particular. In studies investigating efficacy in major depressive disorder, not all antidepressants have been shown to have clear-cut efficacy in severe depression. Here, the minimum standards for the necessary methodology to investigate efficacy in severe depression are reviewed and the methods that are needed to establish efficacy as a superior antidepressant or as an antidepressant with a faster than expected response are suggested. A review of the mechanisms of action of different antidepressants is accompanied by a critical review of the properties of an antidepressant likely to achieve either efficacy in severe depression or the status of a superior antidepressant.

The importance of long-term tolerability in achieving recovery

Many patients with depression require long-term treatment to provide optimal clinical outcomes. Long-term tolerability is therefore important in facilitating adherence to treatment and thereby maintaining control over depressive symptoms. While the newer selective serotonin reuptake inhibitors (SSRIs) and serotonin noradrenaline reuptake inhibitors (SNRIs) are generally better tolerated than older treatments, such as tricyclic antidepressants and monoamine oxidase inhibitors, they can still cause nausea, headache, sleep disturbances, dry mouth, weight gain and sexual dysfunction. However, SSRIs and SNRIs differ in the extent to which they are associated with adverse events. Available data suggest that treatment of depression with escitalopram (an SSRI) may result in fewer side effects than citalopram or paroxetine (other SSRIs), or venlafaxine (an SNRI). Adverse events decrease with time during long-term escitalopram treatment, and in one study, after a 52-week escitalopram treatment, fewer than 10% of patients had withdrawn due to adverse events. Escitalopram is well tolerated during long-term treatment and appears better tolerated than some other SSRIs and venlafaxine. This improved tolerability is particularly important when selecting an antidepressant for long-term use.

Clinical effects of pharmacological variations in selective serotonin reuptake inhibitors: an overview

Although the selective serotonin reuptake inhibitor (SSRI) class of antidepressants shares a common primary pharmacology, namely the inhibition of serotonin reuptake, their secondary pharmacology is remarkably heterogeneous. Inhibition of serotonin reuptake and the consequent increase in serotonin availability are responsible for the relief of depressive symptoms and for some of the adverse effects of this class of drugs. Transsynaptic effects such as modulation of signalling cascades, gene expression processes and neuroplasticity are also important in the mechanism of action of antidepressants. However, this review shows that secondary properties of the SSRIs may contribute to the differences in efficacy and tolerability between members of the class. For example, fluvoxamine has affinity for sigma(1)-receptors -- a property likely to be responsible for its particular efficacy in delusional depression. By understanding the properties of SSRIs and employing careful selection of agents for individual patients, physicians are more able to tailor antidepressant treatments to their patients' particular circumstances.

Luteal phase treatment of premenstrual dysphoric disorder improves symptoms that continue into the postmenstrual phase

BACKGROUND

Despite the proven efficacy of luteal phase medication dosing for women with premenstrual dysphoric disorder (PMDD), it is not known whether this approach adequately treats symptoms that linger into the first 2-3 days of the follicular phase, a time when up to one-third of women diagnosed with PMDD report residual symptoms. Furthermore, no previous study has explored whether abruptly stopping medication after 2 weeks of treatment is associated with discontinuation symptoms.

METHODS

To evaluate the efficacy of luteal phase medication dosing, symptom data from the Daily Record of Severity of Problems (DRSP) during first few days of menses were compared from two studies with similar designs but different treatment strategies. The first study used continuous dosing of sertraline, 50-150 mg/day, throughout the menstrual cycle, while the second study used intermittent dosing with sertraline, 50-100 mg/day in the 14-16 days prior to onset of menses. To investigate whether abruptly stopping pills led to discontinuation symptoms, DRSP data for the first 5 days after the onset of menses were analyzed in the second (intermittent dosing) study. Symptom scores were compared for subjects who took either sertraline or placebo premenstrually and ceased taking pills at the onset of menses.

RESULTS

The baseline (pretreatment) to on-treatment effect sizes were similar for continuous vs. luteal phase dosing on the first day of menses (0.73 vs. 0.89), second day of menses (0.40 vs. 0.55), and third day of menses (0.42 vs. 0.44), respectively. Subjects who abruptly discontinued sertraline had fewer symptoms indicative of withdrawal at Day 3 (p < 0.01) and no difference during Days 4-5 compared to subjects abruptly discontinuing placebo.

CONCLUSION

Patients given active medication during the luteal phase demonstrate reductions in DRSP total scores into the first few days of menses regardless of whether active treatment was continuous throughout the menstrual cycle or was discontinued at the onset of menses. This analysis finds no support for discontinuation symptoms following abrupt cessation of sertraline after 2 weeks of treatment for two cycles.

Absence of discontinuation symptoms with agomelatine and occurrence of discontinuation symptoms with paroxetine: a randomized, double-blind, placebo-controlled discontinuation study

The effects of an abrupt interruption of agomelatine, a new melatonergic/serotonergic antidepressant, were explored in a double-blind, placebo-controlled study. Paroxetine was used as active control. After 12 weeks of double-blind treatment with agomelatine 25 mg/day or paroxetine 20 mg/day, sustained remitted depressed patients were randomized for 2 weeks, under double-blind conditions, to placebo or to their initial antidepressant treatment. Discontinuation symptoms were assessed at the end of the first and second week of discontinuation with the Discontinuation Emergent Signs and Symptoms (DESS) checklist. One hundred and ninety-two sustained remitted patients were randomized to the 2-week discontinuation period. Patients who discontinued agomelatine did not experience more discontinuation symptoms than those who continued on agomelatine. Patients who discontinued paroxetine for placebo experienced significantly more DESS discontinuation symptoms, during the first week, compared to those who continued with paroxetine (respective mean number of emergent symptoms: 7.3+/-7.1 and 3.5+/-4.1, P<0.001). No significant difference was shown between the continuing and interrupting groups in the second week of discontinuation. By contrast to paroxetine, abrupt cessation of agomelatine is not associated with discontinuation symptoms.

Subjective assessment of the effects of CNS-active drugs on sleep by the Leeds sleep evaluation questionnaire: a review

The Leeds sleep evaluation questionnaire (LSEQ) comprises ten self-rating 100 mm line analogue questions concerned with sleep and early morning behaviour. A literature search identified 83 studies in peer-reviewed journals that reported the use of the LSEQ for psychopharmacological investigations of drug effects on self-reported aspects of sleep. High internal consistency and reliability of the questionnaire have been demonstrated. Findings from studies involving a variety of psychoactive agents indicated that the LSEQ was able to quantify subjective impressions of sleep and waking and the effects of drugs in healthy volunteers, depressed and insomnia patients. In accordance with their known activity profile nocturnal administration of sedative hypnotic agents and antihistamines induced dose-related improvements in self-reported ease of getting to sleep, and quality of sleep but a decrease in alertness and behavioural integrity the following morning. Psychostimulants, on the other hand, impaired subjective ratings of sleep and increased early morning alertness. Antidepressants and certain anxiolytic agents improved both self-reported sleep aspects and early morning alertness. Treatment effects measured by the LSEQ corresponded to those measured for the same drugs by other assessment methods. These data indicate that the LSEQ is a robust and reliable instrument for psychopharmacological evaluations. Self-evaluations of sleep, as obtained by the LSEQ, can therefore provide consistent and meaningful measures for estimating the effectiveness of sleep modulators and sedative-hypnotic drugs.

Focus on paroxetine

This review of paroxetine is based on Medline and PsycLit searches and a manual search of the available research literature. It aims to cover the pharmacology of this frequently prescribed SSRI antidepressant in terms of its indications, efficacy and adverse effects. Overall, paroxetine is a well-tolerated and safe first-line SSRI antidepressant with anxiolytic qualities. It has been found useful in depression, anxiety and other conditions such as obsessive compulsive disorder and post-traumatic stress disorder. The antidepressant has some advantages over earlier tricyclic medication in terms of a lack of cardiovascular side-effects and relative safety in overdose. Cessation of use, however, is associated with withdrawal or discontinuation symptoms and patients should be counselled as to how these might be avoided. A 3- or 4-week graded withdrawal regimen, perhaps with concomitant fluoxetine to cover serotonergic discontinuation symptoms, may be advisable.

Selective Serotonin Reuptake Inhibitor Discontinuation Syndrome

Based on emerging research findings, nurses are urged to become more aware of SSRI discontinuation syndrome. To ameliorate or avoid the associated symptoms, client education is recommended, and dosage tapering is encouraged whenever possible. Although the symptoms associated with discontinuation syndrome usually are mild, they may pose particular safety concerns for clients with co-occurring conditions. In these situations, precautions should be taken to prevent exacerbation of existing problems.

Serotonin agents in the treatment of acquired brain injury

BACKGROUND

The development of novel serotonin agents has led to an increased use of these medications throughout medical practice. An understanding of the basic pharmacological function of these agents is key to understanding their usefulness. Among persons with brain injury, serotonin agents have been used for the treatment of depression, panic disorder, obsessive-compulsive disorders, agitation, sleep disorders, and motor dysfunction.

CONCLUSION

This article will review the mechanisms, efficacy, and side effects of serotonin agents with a focus on persons with brain injury.

Discontinuation syndrome in dysthymic patients treated with selective serotonin reuptake inhibitors: a clinical investigation

OBJECTIVE

Many authors have reported discontinuation symptoms associated with selective serotonin reuptake inhibitors (SSRIs). The aim of this study was to investigate the incidence and characteristics of the discontinuation syndrome in patients who stopped treatment with the SSRIs paroxetine and fluoxetine under the usual conditions of clinical practice, and to identify clinical predictors of the syndrome.

METHODS

Ninety-seven outpatients who received an initial diagnosis of dysthymic disorder, who responded to >or=8 weeks treatment with paroxetine (n = 52) or fluoxetine (n = 45), and who discontinued the SSRI according to their psychiatrist's instructions were included. They were assessed at the time of discontinuation using a semi-structured interview for clinical and treatment characteristics, the Hamilton Depression Rating Scale (HAM-D) and the Montgomery-Asberg Depression Rating Scale (MADRS). Patients were then assessed 4 weeks later using a checklist for discontinuation symptoms, a semi-structured interview for discontinuation symptom characteristics, and the HAM-D and the MADRS.

RESULTS

A discontinuation syndrome was found in 26 patients (26.8% of our sample); of this group, 22 patients (84.6%) had received paroxetine, and 4 patients (15.4%) had received fluoxetine. The mean time at onset of symptoms was 2 days after drug discontinuation and the mean duration was 5 days. The statistical comparison between the groups with and without a discontinuation syndrome found two significant differences - a discontinuation syndrome was more common in patients treated with paroxetine and in patients with an earlier onset of dysthymic disorder. Multiple regression analysis confirmed that these two factors were related to the duration of discontinuation symptoms, while the number of symptoms was associated with three factors, including use of paroxetine, age at onset of dysthmia and female gender.

CONCLUSIONS

A discontinuation syndrome is common after treatment with SSRIs is stopped in patients with dysthymia, and it appears to be more common in patients receiving paroxetine than in those receiving fluoxetine. The syndrome is related both to drug and clinical characteristics. The features of the syndrome in patients with different Axis I diagnoses should be compared in further investigations.

Paroxetine: an update of its use in psychiatric disorders in adults

Paroxetine is a selective serotonin reuptake inhibitor (SSRI), with antidepressant and anxiolytic activity. In 6- to 24-week well designed trials, oral paroxetine 10 to 50 mg/day was significantly more effective than placebo, at least as effective as tricyclic antidepressants (TCAs) and as effective as other SSRIs and other antidepressants in the treatment of major depressive disorder. Relapse or recurrence over 1 year after the initial response was significantly lower with paroxetine 10 to 50 mg/day than with placebo and similar to that with imipramine 50 to 275 mg/day. The efficacy of paroxetine 10 to 40 mg/day was similar to that of TCAs and fluoxetine 20 to 60 mg/day in 6- to 12-week trials in patients aged > or =60 years with major depression. Paroxetine 10 to 40 mg/day improved depressive symptoms to an extent similar to that of TCAs in patients with comorbid illness, and was more effective than placebo in the treatment of dysthymia and minor depression. Paroxetine 20 to 60 mg/day was more effective than placebo after 8 to 12 weeks' treatment of obsessive-compulsive disorder (OCD), panic disorder, social anxiety disorder (social phobia), generalised anxiety disorder (GAD) and post-traumatic stress disorder (PTSD). Improvement was maintained or relapse was prevented for 24 weeks to 1 year in patients with OCD, panic disorder, social anxiety disorder or GAD. The efficacy of paroxetine was similar to that of other SSRIs in patients with OCD and panic disorder and similar to that of imipramine but greater than that of 2'chlordesmethyldiazepam in patients with GAD. Paroxetine is generally well tolerated in adults, elderly individuals and patients with comorbid illness, with a tolerability profile similar to that of other SSRIs. The most common adverse events with paroxetine were nausea, sexual dysfunction, somnolence, asthenia, headache, constipation, dizziness, sweating, tremor and decreased appetite. In conclusion, paroxetine, in common with other SSRIs, is generally better tolerated than TCAs and is a first-line treatment option for major depressive disorder, dysthymia or minor depression. Like other SSRIs, paroxetine is also an appropriate first-line therapy for OCD, panic disorder, social anxiety disorder, GAD and PTSD. Notably, paroxetine is the only SSRI currently approved for the treatment of social anxiety disorder and GAD, which makes it the only drug of its class indicated for all five anxiety disorders in addition to major depressive disorder. Thus, given the high degree of psychiatric comorbidity of depression and anxiety, paroxetine is an important first-line option for the treatment of major depressive disorder, OCD, panic disorder, social anxiety disorder, GAD and PTSD.

The physiological role of 5-HT2A receptors in working memory

Dorsolateral prefrontal cortex has an essential role in the cognitive process of working memory, dysfunction of which is considered to be a core deficit in schizophrenia. Although this cortical region is densely innervated with 5-HT2A receptors to which atypical antipsychotic drugs bind with high affinity, little is known of the influence of this serotonin receptor subtype on prefrontal function. We addressed this issue by examining the effects of iontophoresis of selective receptor ligands on prefrontal neurons possessing spatially tuned delay activity, or "memory fields," in monkeys performing a delayed-response task. Memory fields of putative pyramidal cells were attenuated by iontophoresis of 5-HT2A antagonists, which primarily produced a reduction in delay activity for preferred target locations. Conversely, 5-HT2A stimulation by alpha-methyl-5-HT or 5-HT itself, accentuated the spatial tuning of these neurons by producing a modest increase in activity for preferred target locations and/or a reduction in activity for nonpreferred locations. The agonist effects could be reversed by the selective antagonist MDL100,907, and were dose-dependent, such that high levels attenuated spatial tuning by profoundly reducing delay activity. A role for feedforward inhibitory circuitry in these effects was supported by the finding that 5-HT2A blockade also attenuated the memory fields of putative interneurons. We conclude that prefrontal 5-HT2A receptors have a hitherto unrecognized role in the cognitive function of working memory, which involves actions at both excitatory and inhibitory elements within local circuitry.

Selective serotonin reuptake inhibitor discontinuation syndrome: a review

Selective serotonin reuptake inhibitors (SSRIs) are widely prescribed in the treatment of depression and anxiety, as well as obsessive-compulsive, eating, and impulse-control disorders. Paralleling their widespread use has been an increase in adverse-effect reports not noted during short-term efficacy studies. Significant among these adverse effects is SSRI discontinuation syndrome, which follows the interruption of extended treatment or a reduction in drug dosage and entails somatic and psychological symptoms. These self-limiting symptoms resolve on reintroduction of the drug and cannot be explained as a remanifestation of the original disorder. To facilitate proper diagnosis and avoid unnecessary therapeutic or diagnostic interventions, all physicians who prescribe SSRIs should become familiar with these symptoms. The most appropriate approach to therapy for discontinuation syndrome involves educating patients and reassuring them that this is a reversible condition, reinstating the original SSRI, and further slowing the rate of tapering.