Hormonal markers of stress response following interruption of selective serotonin reuptake inhibitor treatment

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.

[Lithium Withdrawal Symptoms - A Systematic Review]

BACKGROUND

Withdrawal symptoms of lithium have not been systematically assessed to date.

AIM

Systematic review of withdrawal symptoms after discontinuation of pharmacological treatment with lithium.

METHODS

Systematic literature search in PubMed and reference lists of relevant articles. We included clinical trials and case reports.

RESULTS

Out of 249 articles, six met our inclusion criteria, entailing six trials and a case series. Four trials and three case reports point to the existence of a withdrawal syndrome after discontinuation of lithium. Occurrence of symptoms was not dependent on the primary disorder for which lithium was initiated. Frequently reported symptoms were irritability, restlessness and somatic symptoms like vertigo, dizziness or lightheadedness. Symptoms occurred within the first week and were generally mild and self-limiting within weeks.

CONCLUSION

Current evidence indicates that withdrawal symptoms after discontinuation of lithium can occur. There is a need for controlled studies of high methodological quality in order to assess predictors of and prevention strategies for discontinuation syndromes.

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.

Insulin-like growth factor-1: a possible marker for emotional and cognitive disturbances, and treatment effectiveness in major depressive disorder

Depression and cognitive dysfunction share a common neuropathological platform. Abnormal neural plasticity in the frontolimbic circuits has been linked to changes in the expression of neurotrophic factors, including IGF-1. These changes may result in clinical abnormalities observed over the course of major depressive disorder (MDD), including cognitive dysfunction. The present review aimed to summarize evidence regarding abnormalities of peripheral IGF-1 in MDD patients and assess a marker and predictive role of the neurotrophin for emotional and cognitive disturbances, and treatment effectiveness. A literature search of the PubMed database was conducted for studies, in which peripheral IGF-1 levels were evaluated. Our analysis revealed four main findings: (1) IGF-1 levels in MDD patients mismatch across the studies, which may arise from various factors, e.g., age, gender, the course of the disease, presence of cognitive impairment, ongoing therapy, or general health conditions; (2) the initial peripheral IGF-1 levels may predict the occurrence of depression in future; (3) peripheral IGF-1 levels may reflect cognitive dysfunction, although the data is limited; (4) it is difficult to evaluate the influence of treatment on IGF-1 levels as there is discrepancy of this growth factor among the studies at baseline, although most of them showed a decrease in IGF-1 levels after treatment.

Rhodiola rosea L. as a putative botanical antidepressant

BACKGROUND

Rhodiola rosea (R. rosea) is a botanical adaptogen with putative anti-stress and antidepressant properties. Evidence-based data supporting the effectiveness of R. rosea for depression in adults is limited, and therefore a comprehensive review of available animal and human studies suggesting a putative antidepressant action is warranted.

PURPOSE

A review of the literature was undertaken to ascertain studies of possible antidepressant mechanisms of action and studies of the safety and effectiveness of R. rosea extracts in animals and adult humans.

METHODS

A search of MEDLINE and the Russian state library database was conducted (up to October 2015) on R. rosea.

MECHANISM OF ACTION

R. rosea extracts and its purified constituent, salidroside, has been shown to produce a variety of mediator interactions with several molecular networks of neuroendocrine-immune and neurotransmitter receptor systems likely to be involved in the pathophysiology of depression. A wide variety of preclinical in vivo and ex vivo studies with laboratory animals suggests the presence of several biochemical and pharmacological antidepressant-like actions.

EFFECTIVENESS

Clinical assessment of R. rosea L. rhizome extracts in humans with various depressive syndromes is based upon results from two randomized, double-blind, placebo-controlled trials of 146 subjects with major depressive disorder and seven open-label studies totaling 714 individuals with stress-induced mild depression (diagnosed as asthenic syndrome or psychoneurosis). Overall, results of these studies suggests a possible antidepressant action for R. rosea extract in adult humans.

SAFETY

In contrast to most conventional antidepressants, R. rosea extract appears to be well-tolerated in short-term studies with a favorable safety profile.

CONCLUSIONS

R. rosea demonstrates multi-target effects on various levels of the regulation of cell response to stress, affecting various components of the neuroendocrine, neurotransmitter receptor and molecular networks associated with possible beneficial effects on mood.

Role of trophic factors GDNF, IGF-1 and VEGF in major depressive disorder: A comprehensive review of human studies

RATIONALE

The neurotrophin hypothesis of major depressive disorder (MDD) postulates that this illness results from aberrant neurogenesis in brain regions that regulates emotion and memory. Notwithstanding this theory has primarily implicated BDNF in the neurobiology of MDD. Recent evidence suggests that other trophic factors namely GDNF, VEGF and IGF-1 may also be involved.

PURPOSE

The present review aimed to critically summarize evidence regarding changes in GDNF, IGF-1 and VEGF in individuals with MDD compared to healthy controls. In addition, we also evaluated the role of these mediators as potential treatment response biomarkers for MDD.

METHODS

A comprehensive review of original studies studies measuring peripheral, central or mRNA levels of GDNF, IGF-1 or VEGF in patients with MDD was conducted. The PubMed/MEDLINE database was searched for peer-reviewed studies published in English through June 2nd, 2015.

RESULTS

Most studies reported a reduction in peripheral GDNF and its mRNA levels in MDD patients versus controls. In contrast, IGF-1 levels in MDD patients compared to controls were discrepant across studies. Finally, most studies reported high peripheral VEGF levels and mRNA expression in MDD patients compared to healthy controls.

CONCLUSIONS

GDNF, IGF-1 and VEGF levels and their mRNA expression appear to be differentially altered in MDD patients compared to healthy individuals, indicating that these molecules might play an important role in the pathophysiology of depression and antidepressant action of therapeutic interventions.

The mechanisms by which antidepressants may reduce coronary heart disease risk

BACKGROUND

Depression is known to increase the risk for coronary heart disease (CHD) likely through various pathogenetic actions. Understanding the links between depression and CHD and the effects of mediating these links may prove beneficial in CHD prevention.

METHODS

An integrated model of CHD was used to elucidate pathogenetic pathways of importance between depression and CHD. Using biomarker relative risk data the pathogenetic effects are representable as measurable effects based on changes in biomarkers.

RESULTS

A 'connection graph' presents interactions by illustrating the relationship between depression and the biomarkers of CHD. The use of selective serotonin reuptake inhibitors (SSRIs) is postulated to have potential to decrease CHD risk. Comparing the 'connection graph' of SSRI's to that of depression elucidates the possible actions through which risk reduction may occur.

CONCLUSIONS

The CHD effects of depression appear to be driven by increased inflammation and altered metabolism. These effects might be mediated with the use of SSRI's.

New insights on the antidepressant discontinuation syndrome

OBJECTIVE

Antidepressants are at best 50–55% effective. Non-compliance and the antidepressant discontinuation syndrome (ADS) are causally related yet poorly appreciated. While ADS is associated with most antidepressants, agomelatine seems to be devoid of such risk. We review the neurobiology and clinical consequences of antidepressant non-compliance and the ADS. Agomelatine is presented as a counterpoint to learn more on how ADS risk is determined by pharmacokinetics and pharmacology.

DESIGN

The relevant literature is reviewed through a MEDLINE search via PubMed, focusing on agomelatine and clinical and preclinical research on ADS.

RESULTS

Altered serotonergic dysfunction appears central to ADS so that how an antidepressant targets serotonin will determine its relative risk for inducing ADS and thereby affect later treatment outcome. Low ADS risk with agomelatine versus other antidepressants can be ascribed to its unique pharmacokinetic characteristics as well as its distinctive actions on serotonin, including melatonergic, monoaminergic and glutamatergic-nitrergic systems.

CONCLUSIONS

This review raises awareness of the long-term negative aspects of non-compliance and inappropriate antidepressant discontinuation, and suggests possible approaches to “design-out” a risk for ADS. It reveals intuitive and rational ideas for antidepressant drug design, and provides new thoughts on antidepressant pharmacology, ADS risk and how these affect long-term outcome.

Pathophysiology of hypercortisolism in depression: pituitary and adrenal responses to low glucocorticoid feedback

OBJECTIVE

To test three theories of hypercortisolemia in depression-hypothalamic overdrive, impaired glucocorticoid feedback, or autonomous cortisol production.

METHOD

We applied an overnight low-cortisol feedback strategy by administering metyrapone to hypercortisolemic depressed in-patients and control subjects.

RESULTS

Under metyrapone, the increases of plasma adrenocorticotropic hormone (ACTH) concentrations and of basal and pulsatile ACTH secretion were not exaggerated in hypercortisolemic depressed patients compared with control subjects. ACTH approximate entropy (ApEn) did not differ at baseline or under metyrapone. Thus, neither hypothalamic overdrive nor irregular ACTH secretion was seen. We did not detect impaired cortisol feedback: the ACTH response was not reduced, and ApEn measures that are sensitive to feedback changes were comparable in both groups. Metyrapone disrupted cortisol secretory regularity in depressed and control subjects. On the baseline day, basal cortisol secretion was significantly increased and was highly irregular (high ApEn), and ACTH-cortisol cross-ApEn was markedly elevated in high-cortisol patients.

CONCLUSION

Classical feed-forward overdrive and impaired feedback theories of hypercortisolemia in depression were not supported. Depressive hypercortisolemia may result from alternative pathophysiological mechanisms involving irregular basal hypersecretion of cortisol, associated with adrenal enlargement, possibly through splanchnic sympathetic activation of the adrenal cortex.

Changes in cortisol secretion during antidepressive treatment and cognitive improvement in patients with major depression: a longitudinal study

OBJECTIVES

We have previously reported that cognitive deficits are cross-sectionally associated with elevated cortisol in depressed patients. Here, we longitudinally examined if changes in cortisol secretion during treatment are associated with improvement of cognition.

METHODS

Cognitive function and salivary cortisol levels were longitudinally examined in 52 patients with major depression before and after 3 weeks of standardized selective serotonin reuptake inhibitor (SSRI) and an add-on treatment modulating the mineralocorticoid receptor and compared to a healthy control group (n=50) matched for age, gender and years of education.

RESULTS

Across add-on treatment groups, SSRI treatment reduced salivary cortisol in patients to levels of healthy controls (time×group interaction p=.05). In patients, reduction of cortisol significantly correlated with improvement in depressive symptoms (r=.52, p<.01), speed of information processing (r=.50, p<.01), and cognitive set-shifting (r=.34, p=.03). Improved depressive symptoms were only associated with improved attention and working memory.

CONCLUSIONS

Improvement of some cognitive domains during SSRI treatment was associated with decreasing cortisol secretion and was only to a lesser extent associated with improved depressive symptoms.

The mechanisms of tolerance in antidepressant action

There is increasing awareness that, in some cases, long-term use of antidepressant drugs (AD) may enhance the biochemical vulnerability to depression and worsen its long-term outcome and symptomatic expression, decreasing both the likelihood of subsequent response to pharmacological treatment and the duration of symptom-free periods. A review of literature suggesting potential side effects during long treatment with antidepressant drugs was performed. Studies were identified electronically using the following databases: Medline, Cinahl, PsychInfo, Web of Science and the Cochrane Library. Each database was searched from its inception date to April 2010 using "tolerance", "withdrawal", "sensitization", "antidepressants" and "switching" as key words. Further, a manual search of the psychiatric literature has been performed looking for articles pointing to paradoxical effects of antidepressant medications. Clinical evidence has been found indicating that even though antidepressant drugs are effective in treating depressive episodes, they are less efficacious in recurrent depression and in preventing relapse. In some cases, antidepressants have been described inducing adverse events such as withdrawal symptoms at discontinuation, onset of tolerance and resistance phenomena and switch and cycle acceleration in bipolar patients. Unfavorable long-term outcomes and paradoxical effects (depression inducing and symptomatic worsening) have also been reported. All these phenomena may be explained on the basis of the oppositional model of tolerance. Continued drug treatment may recruit processes that oppose the initial acute effect of a drug. When drug treatment ends, these processes may operate unopposed, at least for some time and increase vulnerability to relapse. Antidepressant drugs are crucial in the treatment of major depressive episodes. However, appraisal and testing of the oppositional model of tolerance may yield important insights as to long-term treatment and achievement of enduring effects.

A register study of the impact of stopping third trimester selective serotonin reuptake inhibitor exposure on neonatal health

OBJECTIVE

To determine whether risk for adverse neonatal outcomes are reduced by stopping SSRI use before the end of pregnancy.

METHOD

Using population health data, maternal health and prenatal SSRI prescriptions were linked to neonatal birth records (N = 119,547) (1998-2001). Neonates SSRI-exposed in the last 14 days (L14) of gestation were compared with infants who had gestational exposure, but not during the last 14 days (NL14). Propensity score matching was used to control for potential confounders (total exposure, maternal health characteristics).

RESULTS

Increased risk for neonatal respiratory distress was present where L14 exposure occurred compared with risk where exposure stopped before L14. However, controlling for potential maternal and neonatal confounders, differences disappeared.

CONCLUSION

Controlling for maternal illness severity, reducing exposure to SSRI's at the end of pregnancy had no significant clinical effect on improving neonatal health. These findings raise the possibility that some adverse neonatal outcomes may not be an acute pharmacological condition such as toxicity or withdrawal.

Zinc supplementation augments efficacy of imipramine in treatment resistant patients: a double blind, placebo-controlled study

BACKGROUND

One of the main problems in the therapy of depression is the limited efficacy of antidepressants and the limited utility of augmentation strategies. Zinc, a non competitive NMDA receptor antagonist exhibits preclinical antidepressant efficacy. Moreover, a preliminary clinical report suggests augmentation of antidepressant therapy by zinc in depression.

METHODS

A placebo-controlled, double blind study of zinc supplementation in imipramine therapy was conducted in sixty, 18-55-year old, unipolar depressed patients fulfilling the DSM-IV criteria for major depression without psychotic symptoms. After a one week washout period, patients were randomized into two groups treated with imipramine (approximately 140 mg/day) and receiving once daily either placebo (n=30) or zinc supplementation (n=30, 25 mgZn/day) for 12 weeks.

RESULTS

No significant differences in CGI, BDI, HADRS and MADRS scores were demonstrated between zinc-supplemented and placebo-supplemented antidepressant treatment non-resistant patients. However, zinc supplementation significantly reduced depression scores and facilitated the treatment outcome in antidepressant treatment resistant patients.

CONCLUSION

Zinc supplementation augments the efficacy and speed of onset of therapeutic response to imipramine treatment, particularly in patients previously nonresponsive to antidepressant pharmacotherapies. These data suggest the participation of disturbed zinc/glutamatergic transmission in the pathophysiology of drug resistance.

Is major depressive disorder a metabolic encephalopathy?

Metabolic encephalopathy is an acute disturbance in cellular metabolism in the brain evoked by conditions of hypoxia, hypoglycaemia, oxidative stress and/or inflammation. It usually develops acutely or subacutely and is reversible if the systemic disorder is treated. If left untreated, however, metabolic encephalopathy may result in secondary structural damage to the brain. Most encephalopathies are present with neuropsychiatric symptoms, one in particular being depression. However, mood disorders are often co-morbid with cardiovascular, liver, kidney and endocrine disorders, while increasing evidence concurs that depression involves inflammatory and neurodegenerative processes. This would suggest that metabolic disturbances resembling encephalopathy may underscore the basic neuropathology of depression at a far deeper level than currently realized. Viewing depression as a form of encephalopathy, and exploiting knowledge gleaned from our understanding of the neurochemistry and treatment of metabolic encephalopathy, may assist in our understanding of the neurobiology of depression, but also in realizing new ideas in the pharmacotherapy of mood disorders.

Whatever happened to symptom substitution?

Symptom substitution is a theoretical consequence of the psychodynamic model of psychopathology and symptom formation that contrasts markedly with behavioral models. Symptom substitution was a major scientific and clinical question about a half century ago that was abandoned rather than answered partly because it did not seem to occur and partly because perceived methodological problems impeded empirical research. The contemporary relevance of symptom substitution is that the psychodynamic model of psychopathology and symptom formation from which the prediction of symptom substitution stems continues to be widely taught and to broadly inform clinical practice. This article revisits the psychodynamic model of symptom formation and substitution, restates perceived methodological limitations to its empirical study, demonstrates that symptom substitution is an empirically testable prediction, reviews the relevant empirical literature, and discusses implications for the science and practice of clinical psychology including a proposed research design for certifying bona fide psychoanalytic symptoms.

Increased hippocampal nitric oxide synthase activity and stress responsiveness after imipramine discontinuation: role of 5HT 2A/C-receptors

Chronic depressive illness may cause shrinkage of the hippocampus with stress-induced release of glutamate and nitric oxide possibly causally linked to this pathology. Poor antidepressant compliance may contribute to this pathology as well as to long term morbidity. However, antidepressant withdrawal-associated symptoms in depressed patients often reflect hyperserotonergia. The effect of chronic imipramine (IMI; 15 mg/kg/d ip x 3wks) treatment and withdrawal on swim stress responsiveness was studied in Sprague-Dawley rats together with assay of hippocampal NO synthase (NOS) activity. The dependence of any biobehavioral changes following IMI withdrawal on 5HT(2A/C) receptor-mediated events was studied using the 5HT(2A/C) receptor antagonist, ritanserin (RIT; 4 mg/kg/day ip x 7 days), administered alone or during IMI withdrawal. IMI significantly inhibited the situational stress response to forced swimming while also significantly decreasing NOS activity. IMI withdrawal was associated with a significant increase in swim immobility together with a significant increase in NOS activity compared to both control and IMI-treated groups. RIT re-established the anti-immobility effects and reversed NOS hyper-function during IMI withdrawal, although alone it increased NOS activity. Antidepressant discontinuation therefore increases stress responsiveness together with disinhibition of hippocampal NOS through a mechanism involving 5HT(2A/C) receptor activation. The resulting increased nitrergic activity may have significant implications for depressive illness and its treatment.

Modulation of the growth hormone-insulin-like growth factor (GH-IGF) axis by pharmaceutical, nutraceutical and environmental xenobiotics: an emerging role for xenobiotic-metabolizing enzymes and the transcription factors regulating their expression. A review

The growth hormone-insulin-like growth factor (GH-IGF) axis has gained considerable focus over recent years. One cause of this increased interest is due to a correlation of age-related decline in plasma GH/IGF levels with age-related degenerative processes, and it has led to the prescribing of GH replacement therapy by some practitioners. On the other hand, however, research has also focused on the pro-carcinogenic effects of high GH-IGF levels, providing strong impetus for finding regimes that reduce its activity. Whereas the effects of GH/IGF activity on the action of xenobiotic-metabolizing enzyme systems is reasonably well appreciated, the effects of xenobiotic exposure on the GH-IGF axis has not received substantial review. Relevant xenobiotics are derived from pharmaceutical, nutraceutical and environmental exposure, and many of the mechanisms involved are highly complex in nature, not easily predictable from existing in vitro tests and do not always predict well from in vivo animal models. After a review of the human and animal in vivo and in vitro literature, a framework for considering the different levels of direct and indirect modulation by xenobiotics is developed herein, and areas that still require further investigation are highlighted, i.e. the actions of common endocrine disruptors such as pesticides and phytoestrogens, as well as the role of xenobiotic-metabolizing enzymes and the transcription factors regulating their expression. It is anticipated that a fuller appreciation of the existing human paradigms for GH-IGF axis modulation gained through this review may help explain some of the variation in levels of plasma IGF-1 and its binding proteins in the population, aid in the prescription of particular dietary regimens to certain individuals such as those with particular medical conditions, guide the direction of long-term drug/nutraceutical safety trials, and stimulate ideas for future research. It also serves to warn athletes that using compounds touted as performance enhancing because they promote short-term GH release could in fact be detrimental to performance in the long-run.

Neurobiology of antidepressant withdrawal: implications for the longitudinal outcome of depression

Inappropriate discontinuation of drug treatment and noncompliance are a leading cause of long-term morbidity during treatment of depression. Increasing evidence supports an association between depressive illness and disturbances in brain glutamate activity, nitric oxide synthesis, and gamma-amino butyric acid. Animal models also confirm that suppression of glutamate N-methyl-D-aspartate receptor activity or inhibition of the nitric oxide-cyclic guanosine monophosphate pathway, as well as increasing brain levels of gamma-amino butyric acid, may be key elements in antidepressant action. Imaging studies demonstrate, for the most part, decreased hippocampal volume in patients with depression, which may worsen with recurrent depressive episodes. Preclinical models link this potentially neurodegenerative pathology to continued stress-evoked synaptic remodeling, driven primarily by the release of glucocorticoids, glutamate, and nitric oxide. These stress-induced structural changes can be reversed by antidepressant treatment. In patients with depression, antidepressant withdrawal after chronic administration is associated with a stress response as well as functional and neurochemical changes. Preclinical data also show that antidepressant withdrawal evokes a behavioral stress response that is associated with increased hippocampal N-methyl-D-aspartate receptor density, with both responses dependent on N-methyl-D-aspartate receptor activation. Drawing from both clinical and preclinical studies, this article proposes a preliminary molecular perspective and hypothesis on the neuronal implications of adherence to and discontinuation of antidepressant medication.

Selective serotonin reuptake inhibitor discontinuation syndrome is associated with a rostral anterior cingulate choline metabolite decrease: a proton magnetic resonance spectroscopic imaging study

The selective serotonin reuptake inhibitor (SSRI) discontinuation syndrome (DS) is an important potential complication of treatment for major depression. We hypothesized that SSRI treatment discontinuation, resulting in change in clinical state, would be associated with reduced rostral anterior cingulate choline (Cho) metabolite ratios. Individuals with a DSM-III-R diagnosis of unipolar major depression who had been stabilized on paroxetine (n = 13) or fluoxetine (n = 13) were study subjects. They were monitored for change in clinical state (mood ratings, discontinuation symptoms) and underwent proton magnetic resonance spectroscopic imaging of the rostral anterior cingulate 3 days after medication substitution with active SSRI and placebo.Placebo-day Cho/Cre (choline/total creatine) metabolite ratios were decreased in four paroxetine and two fluoxetine subjects meeting DS criteria, as compared with asymptomatic subjects (Mann-Whitney z = -2.31, p =.021). Discontinuation syndrome is associated with a rostral anterior cingulate Cho/Cre metabolite ratio decrease that may reflect dynamics of rostral anterior cingulate function.

Course of illness, hippocampal function, and hippocampal volume in major depression

Studies have examined hippocampal function and volume in depressed subjects, but none have systematically compared never-treated first-episode patients with those who have had multiple episodes. We sought to compare hippocampal function, as assessed by performance on hippocampal-dependent recollection memory tests, and hippocampal volumes, as measured in a 1.5-T magnetic resonance imager, in depressed subjects experiencing a postpubertal onset of depression. Twenty never-treated depressed subjects in a first episode of depression were compared with matched healthy control subjects. Seventeen depressed subjects with multiple past episodes of depression were also compared with matched healthy controls and to the first-episode patients. Both first- and multiple-episode depressed groups had hippocampal dysfunction apparent on several tests of recollection memory; only depressed subjects with multiple depressive episodes had hippocampal volume reductions. Curve-fitting analysis revealed a significant logarithmic association between illness duration and hippocampal volume. Reductions in hippocampal volume may not antedate illness onset, but volume may decrease at the greatest rate in the early years after illness onset.

NMDA receptor involvement in imipramine withdrawal-associated effects on swim stress, GABA levels and NMDA receptor binding in rat hippocampus

Abrupt antidepressant withdrawal after chronic treatment is associated with a stress response that may negatively affect the long-term outcome of depression, the neurochemical correlates, of which, remain undetermined. Prolonged depression involves the stress-related release of glucocorticoids and glutamate, while response to antidepressants involves gamma-amino butyric acid (GABA) and the glutamate N-methyl-D-aspartate (NMDA) receptor. Here, imipramine (IMI) was administered to rats for three weeks followed by acute withdrawal for seven days. Levels of GABA in the hippocampus (HC), and effects on swim stress immobility (SSI), were determined. Furthermore, glutamate/NMDA receptor binding properties were determined using [(3)H]-CGP-39653. Finally, the ability of dizocilpine (MK801), a glutamate NMDA antagonist, to reverse IMI withdrawal was determined. Chronic IMI (15 mg/kg ip) significantly reduced SSI together with a slight but insignificant decrease in HC GABA levels. However, IMI significantly reduced specific binding (B(max)) of [(3)H]-CGP-39653. Withdrawal of IMI for 7 days resulted in a loss of efficacy on SSI, a slight increase in GABA and a significant reversal of IMI effects on [(3)H]-CGP-39653 binding. MK801 (0.2 mg/kg ip) alone for seven days caused a significant decrease in SSI, a significant suppression of HC GABA, and significantly decreased [(3)H]-CGP-39653 B(max). MK801 during IMI-withdrawal significantly decreased GABA, prompted recovery on SSI, though not significantly, but significantly reversed withdrawal effects on [(3)H]-CGP-39653 B(max). In conclusion, acute antidepressant discontinuation is associated with subtle changes on HC GABA, a resurgence of NMDA receptor density and a loss of its anti-immobility response. These responses are reversed by a NMDA antagonist suggesting that abrupt antidepressant discontinuation mobilises glutamate activity.