Impact of antidepressant discontinuation after acute bipolar depression remission on rates of depressive relapse at 1-year follow-up

OBJECTIVE

While guidelines for treating patients with bipolar depression recommend discontinuing antidepressants within 6 months after remission, few studies have assessed the implications of this strategy on the risk for depressive relapse. This study examined the effect of antidepressant discontinuation or continuation on depressive relapse risk among bipolar subjects successfully treated for an acute depressive episode.

METHOD

Eighty-four subjects with bipolar disorder who achieved remission from a depressive episode with the addition of an antidepressant to an ongoing mood stabilizer regimen were followed prospectively for 1 year. The risk of depressive relapse among 43 subjects who stopped antidepressant treatment within 6 months after remission ("discontinuation group") was compared with the risk among 41 subjects who continued taking antidepressants beyond 6 months ("continuation group").

RESULTS

A Cox proportional hazards regression analysis indicated that shorter antidepressant exposure time following successful treatment was associated with a significantly shorter time to depressive relapse. Furthermore, patients who discontinued antidepressant treatment within the first 6 months after remission experienced a significantly shorter period of euthymia before depressive relapse over the length of 1-year follow-up. One year after successful antidepressant response, 70% of the antidepressant discontinuation group experienced a depressive relapse compared with 36% of the continuation group. By the 1-year follow-up evaluation, 15 (18%) of the 84 subjects had experienced a manic relapse; only six of these subjects were taking an antidepressant at the time of manic relapse.

CONCLUSIONS

The risk of depressive relapse in patients with bipolar illness was significantly associated with discontinuing antidepressants soon after remission. The risk of manic relapse was not significantly associated with continuing use of antidepressant medication and, overall, was substantially less than the risk of depressive relapse. Maintenance of antidepressant treatment in combination with a mood stabilizer may be warranted in some patients with bipolar disorder.

Hippocampal modulation of sensorimotor processes

While the hippocampus makes unique contributions to memory, it has also long been associated with sensorimotor processes, i.e. innate processes involving control of motor responses to sensory stimuli. Moreover, hippocampal dysfunction has been implicated in neuropsychiatric diseases, such as schizophrenia and anxiety disorders, primarily characterized by non-mnemonic deficits in the processing of and responding to sensory information. This review is concerned with the hippocampal modulation of three sensorimotor processes in rats-locomotor activity, prepulse inhibition (PPI) of the startle reflex, and the startle reflex itself-whose alterations are related to human psychosis or anxiety disorders. Its main purpose is to present and discuss the picture emerging from studies examining the effects of pharmacological manipulations of the dorsal and ventral hippocampus by local drug microinfusions. While a role of the hippocampus in regulating locomotor activity, PPI, and startle reactivity has also been suggested based on the effects of hippocampal lesions, the microinfusion studies have revealed additional important details of this role and suggest modifications of notions based on lesion studies. In summary, the microinfusion studies corroborate that hippocampal mechanisms can directly influence locomotor activity, PPI, and startle reactivity, and that aberrant hippocampal function may contribute to neuropsychiatric diseases, in particular psychosis. The relation between different sensorimotor processes and hippocampal neurotransmission, the role of ventral and dorsal hippocampus, and the extrahippocampal mechanisms mediating the hippocampal modulation of different sensorimotor processes can partly be dissociated. Thus, the hippocampal modulation of these sensorimotor processes appears to reflect multiple operations, rather than one unitary operation.

The Delta 32 mutation of the chemokine-receptor 5 gene neither is correlated with chronic hepatitis C nor does it predict response to therapy with interferon-alpha and ribavirin

Unlike in HIV, homozygosity for a 32-bp deletion (Delta 32) of the chemokine receptor 5 (CCR5) gene was recently described in increased frequency in patients with chronic hepatitis C (HCV). Thus, it was speculated that this mutation might be relevant for disease susceptibility and influence the response to antiviral therapy. The present study sought to confirm the association between HCV and the Delta 32 mutation of the CCR5 gene and to correlate it with the response to therapy with interferon-alpha-2a and ribavirin. Sixty-two patients with HCV and 119 healthy unrelated controls were genotyped for the Delta 32 mutation. For the correlation between the Delta 32 mutation and response to therapy, only patients (n = 59) who completed 6 months of combination therapy as part of a prospective study were evaluated. The Delta 32 mutation was not observed in increased frequency in HCV. Furthermore, a significant difference of the HCV load or aminotransferase concentrations was not observed in carriers versus noncarriers of the Delta 32 mutation. After stratification for potentially confounding factors such as gender or HCV genotype, a significant difference was also not detected with respect to treatment outcome. These observations argue strongly against a role of CCR5 for susceptibility to HCV infection or response to combination therapy.

Rapid-cycling bipolar disorder: effects of long-term treatments

OBJECTIVE

To compare responses to long-term treatment of rapid-cycling (RC) vs. non-RC bipolar disorder patients and assess relative effectiveness of specific agents in RC patients.

METHOD

Studies identified by literature searching were analyzed for effects of RC status and treatment-type on clinical outcome (recurrence or non-improvement per exposure-time), using random-effects methods to estimate pooled rates and their 95% CI for quantitative meta-analytic modeling.

RESULTS

Data were obtained from 16 reports with 25 trial-arms involving 1856 (905 RC and 951 non-RC) patients treated with carbamazepine, lamotrigine, lithium, topiramate, or valproate, alone or with other agents over an average of 47.5 months (7347 total patient-years). Estimated RC prevalence was 15.4%. Crude rates (%/month) of recurrence (2.31/1.20) and clinical non-improvement (1.93/0.49) averaged 2.9-fold greater in RC vs. non-RC subjects. The pooled RC/non-RC risk ratio (RR) for inferior treatment-response (in 13 direct comparisons) was 1.40 (CI 1.26-1.56; P < 0.0001). Pooled crude recurrence and non-improvement rates suggested no clear advantage for any treatment, nor superiority for anticonvulsants over lithium. However, only lithium vs. carbamazepine could be directly compared (in four treatment-arms) meta-analytically in RC patients (RR = 0.93, CI 0.74-1.18, indicating no difference in effectiveness).

CONCLUSION

As expected, RC was associated with lower effectiveness of all treatments evaluated. Direct comparisons of specific treatment alternatives for RC patients were rare, and provided no secure evidence of superiority of any treatment. Additional long-term studies comparing RC/non-RC patients randomized to specific treatments are required.

A1 receptor and adenosinergic homeostatic regulation of sleep-wakefulness: effects of antisense to the A1 receptor in the cholinergic basal forebrain

We hypothesized that adenosine, acting via the A1 receptor, is a key factor in the homeostatic control of sleep. The increase in extracellular levels of adenosine during prolonged wakefulness is thought to facilitate the transition to sleep by reducing the discharge activity of wakefulness-promoting neurons in the basal forebrain. Adenosine A1 receptor control of the homeostatic regulation of sleep was tested by microdialysis perfusion of antisense oligonucleotides against the mRNA of the A1 receptor in the magnocellular cholinergic region of the basal forebrain of freely behaving rats. After microdialysis perfusion of A1 receptor antisense in the basal forebrain, spontaneous levels of sleep-wakefulness showed a significant reduction in non-rapid eye movement (REM) sleep with an increase in wakefulness. After 6 hr of sleep deprivation, the antisense-treated animals spent a significantly reduced amount of time in non-REM sleep, with postdeprivation recovery sleep hours 2-5 showing a reduction of approximately 50-60%. There was an even greater postdeprivation reduction in delta power (60-75%) and a concomitant increase in wakefulness. All behavioral state changes returned to control (baseline) values after the cessation of antisense administration. Control experiments with microdialysis perfusion of nonsense (randomized antisense) oligonucleotides and with artificial CSF showed no effect during postdeprivation recovery sleep or spontaneously occurring behavioral states. Antisense to the A1 receptor suppressed A1 receptor immunoreactivity but did not show any neurotoxicity as visualized by Fluoro-Jade staining. These data support our hypothesis that adenosine, acting via the A1 receptor, in the basal forebrain is a key component in the homeostatic regulation of sleep.

Initial lithium and valproate combination therapy in acute mania

Early onset of treatment efficacy is especially important for severe mania syndromes. Lithium has usually a delayed onset of response, which is disadvantageous for inpatient treatment of severe mania. Valproate is effective in treating acute mania and has sedative properties. It has, however, a response rate of approximately only two thirds. Therefore, the initial combination of valproate and lithium was evaluated in a prospective case series of 12 patients, and a retrospective analysis was carried out for 5 patients in comparison with a pretreatment period when lithium therapy was applied without valproate. Outcome criterion for analysis was the latency of response and remission, as well as the amount of neuroleptics used for additional sedation. Patients had a mania syndrome-severity score comparable with the mean mania score of the bipolar manic patients treated in the same unit. All patients under the combination treatment responded. The response occurred within a shorter time compared with the lithium pretreatment episode, which is statistically marginally significant, and the use of neuroleptic medication could be markedly reduced from 18,601.6 mg chlorpromazine equivalents to 3,927.6 mg (p < 0.025). The initial valproate-lithium combination therapy seems to be a safe and effective way to treat severe mania syndromes in the clinic.

Evidence-based guidelines for treating bipolar disorder: recommendations from the British Association for Psychopharmacology

The British Association for Psychopharmacology guidelines specify the scope and target of treatment for bipolar disorder. They are based explicitly on the available evidence and presented, similar to previous Clinical Practice guidelines, as recommendations to aid clinical decision-making for practitioners. They may also serve as a source of information for patients and carers. The recommendations are presented together with a more detailed review of the available evidence. A consensus meeting, involving experts in bipolar disorder and its treatment, reviewed key areas and considered the strength of evidence and clinical implications. The guidelines were drawn up after extensive feedback from participants and interested parties. The strength of supporting evidence was rated. The guidelines cover the diagnosis of bipolar disorder, clinical management and strategies for the use of medicines in short-term treatment of episodes, relapse prevention and stopping treatment.

Alternatives to lithium and divalproex in the maintenance treatment of bipolar disorder

OBJECTIVES

The role of lithium carbonate in the maintenance treatment of bipolar disorder is well established. Unfortunately, many patients fail to respond adequately to this agent or are unable to tolerate its adverse effects. Divalproex has become a commonly used alternative to lithium, but it also is ineffective or poorly tolerated in many patients. This article attempts to review the available data on maintenance therapy in bipolar disorder with a variety of anticonvulsants and antipsychotics (both conventional and novel), with reference to relevant studies in acute mania and bipolar depression as well.

METHODS

Evidence on maintenance therapy and relevant acute-phase data were collected using MEDLINE database searches.

RESULTS

Data on maintenance therapy with agents other than lithium and divalproex are sparse, and often derived from open, uncontrolled studies. Implications and flaws of available data are discussed.

CONCLUSIONS

Other than lithium, there are few robust double-blind data to support the use of a variety of agents in the maintenance phase. However, uncontrolled data suggest that a number of agents merit further study.

GABA-ergic drugs: exit stage left, enter stage right

Drugs that enhance gamma-aminobutyric acid (GABA) activity by interacting at post-synaptic GABA(A) receptors have long been used as hypnotics, sedatives, tranquillizers and anticonvulsants. In this category, benzodiazepines rapidly gained pride of place, replacing barbiturates and becoming the most commonly prescribed of all drugs in the Western world in the 1970s. However, problems such as dependence and withdrawal reactions became apparent in the 1980s, and it seemed that the usefulness of drugs with this mode of action was limited. Recently, focus has shifted to a new group of drugs with GABA-ergic actions mediated through various mechanisms not directly involving the GABA(A) receptor. These drugs include gabapentin, vigabatrin, tiagabine, lamotrigine, pregabalin and others. Although originally developed as anticonvulsants for epilepsy, they appear to have wider applications for use in affective disorders, especially bipolar depression, anxiety disorders and pain conditions. The current information on the properties and therapeutic potential of this new generation of GABA-ergic drugs is reviewed. It remains to be seen whether long-term use leads to tolerance, dependence and withdrawal or discontinuation reactions.

Valproate

OBJECTIVES

This article summarizes the role of valproate as a treatment for bipolar disorder and related conditions.

METHODS

Published studies and reviews were systematically reviewed. Results from randomized, parallel group, double-blind, placebo-controlled studies that included an active comparator are emphasized.

RESULTS

Valproate is an effective treatment for manic patients. Valproate was superior to placebo in one 1-year randomized, parallel group study in rate of recurrence requiring discontinuation, rate of depression requiring discontinuation, total early termination and time to 25% of patients relapsing with mania, and in controlling mild depressive symptoms. On some measures, including time to development of a manic episode, valproate did not differ from placebo. Assessments of maintenance efficacy of valproate and other putative prophylactic treatments for bipolar disorder are problematic, because of the need to analyze multiple indices of efficacy, and practical and ethical issues that limit generalizability of results of placebo-controlled studies. Valproate has some advantages over lithium in treatment of mania for persons with more severe illnesses. Valproate benefits a broader spectrum of bipolar conditions than lithium. Valproate appears at best modestly effective for bipolar depression. Used in combination with several other treatments, additive benefits result, that are greater than with any of the treatments as monotherapy. Side effects are generally mild and manageable, particularly with divalproex. Weight gain and pharmacokinetic interaction with lamotrigine are perhaps the most consistent problems in use. Valproate contributes to neural tube defects if taken during the first trimester of pregnancy, and this risk must be conveyed to women.

CONCLUSIONS

Valproate is an effective and useful treatment for bipolar disorder. Studies clarifying its spectrum of efficacy, its safety and efficacy in combination regimens, and its mechanisms of action are warranted.

Plants and the central nervous system

This review article draws the attention to the many species of plants possessing activity on the central nervous system (CNS). In fact, they cover the whole spectrum of central activity such as psychoanaleptic, psycholeptic and psychodysleptic effects, and several of these plants are currently used in therapeutics to treat human ailments. Among the psychoanaleptic (stimulant) plants, those utilized by human beings to reduce body weight [Ephedra spp. (Ma Huang), Paullinia spp. (guaraná), Catha edulis Forssk. (khat)] and plants used to improve general health conditions (plant adaptogens) were scrutinized. Many species of hallucinogenic (psychodysleptic) plants are used by humans throughout the world to achieve states of mind distortions; among those, a few have been used for therapeutic purposes, such as Cannabis sativa L., Tabernanthe iboga Baill. and the mixture of Psychotria viridis Ruiz and Pav. and Banisteriopsis caapi (Spruce ex Griseb.) C.V. Morton. Plants showing central psycholeptic activities, such as analgesic or anxiolytic actions (Passiflora incarnata L., Valeriana spp. and Piper methysticum G. Forst.), were also analysed.Finally, the use of crude or semipurified extracts of such plants instead of the active substances seemingly responsible for their therapeutic effect is discussed.

The clinical use of gabapentin in bipolar spectrum disorders

BACKGROUND

with increasing awareness of lithium's limitations, several new anticonvulsants had been tested for their mood stabilisation during recent years. Among the innovative third generation mood stabilizing anticonvulsants, gabapentin (GBP) seems to have a broad spectrum of efficacy, although no certain data are available as to its efficacy and use in clinical practice. Accordingly, an extensive review on this subject has been carried out.

METHODS

A computer-generated search of the biomedical literature and abstract books of the more important scientific psychiatric congresses until June 2000 was undertaken to identify all pertinent case reports, case series and studies of GBP as monotherapy or adjunctive therapy in mood disorders. We identified 40 open-label studies on the use of GBP in at least 600 patients with bipolar disorder (BP), manic, depressed, or mixed episodes and unipolar depression and four controlled studies.

RESULTS

The 40 open-label studies and two of the controlled trials suggested that GBP may have a role as adjunctive agent in the treatment of patients with bipolar disorders particularly when complicated by co-morbid anxiety disorder or substance abuse. GBP is usually very well tolerated and has no pharmacological interference with other mood stabilisers. However, in the other two double-blind studies GBP has not been found to be efficacious in the treatment of refractory mania or refractory bipolar depression.

CONCLUSIONS

Although failing to show clear antimanic efficacy in randomized trials, gabapentin still remains a clinically useful agent when it comes to combination treatment in refractory and co-morbid patients.

The pharmacological treatment of bipolar affective disorder: practice is improving but could still be better

Pharmacological treatment of bipolar affective disorder was examined by case note review of 120 subjects under the care of four hospitals in the North-East of England and compared with that recommended in published consensus opinions and also with the findings of previous surveys. Although the only comparison available is with other geographical regions, it appears that lithium use has remained relatively constant in recent years (53% in this sample). The use of anticonvulsants (62%) was greater than in previous studies, as was use of mood stabilizers in combination (37% overall, 53% in rapid cycling subjects). Antidepressant use was found in 23% of subjects. Eleven percent of subjects taking antidepressants were not prescribed a mood stabilizer and 43% of antidepressants prescribed were tricyclics, possibly increasing the risk of switching to mania. Fifteen percent had no mood stabilizer and antipsychotic use was almost equally split between typical and atypical drugs. Practice in the population studied is nearer than treatment described in previous work to that suggested in the literature. This may result from either, or most probably a combination of, the local availability of a specialist mood disorder service and evolution of overall prescribing practice. However, it still falls short in a number of respects of such recommendations as exist and this requires further examination and monitoring.

Unmet clinical needs in bipolar disorder

Bipolar disorder is a complex, chronic condition associated with considerable morbidity and mortality, including a high rate of suicide. Currently available treatment options for bipolar disorder fail to adequately address many of the important needs of bipolar patients. Long-term maintenance therapy with lithium has been shown to prevent further episodes of mania and depression and to decrease the likelihood of suicide. However, many patients stop lithium treatment after only a few weeks, because of either untoward side effects or other factors, such as the belief that they no longer require medication. Even when lithium is taken regularly and at adequate doses, many patients continue to exhibit severe functional disability and also fail to achieve remission. Bipolar depression is also poorly understood and difficult to treat. A number of adjunctive medications are used in combination with lithium, but residual symptoms and recurring episodes of mania and depression remain common. Recently, atypical antipsychotics, such as olanzapine, risperidone, and quetiapine, have been evaluated for the treatment of bipolar disorder. Although considerable research is still needed, preliminary findings suggest that some of these agents may act as mood stabilizers, improving the acute symptoms of mania without inducing depression or rapid cycling. The role of atypical antipsychotics in maintenance therapy for bipolar disorder is currently being evaluated in a number of large clinical trials.

Levetiracetam in the treatment of rapid cycling bipolar disorder

Levetiracetam (LEV) is a novel anticonvulsant that is currently investigated in bipolar disorder. It may be useful in the treatment of refractory and complicated cases, in which conventional mood stabilizers are not effective. We report two cases of rapid cycling bipolar disorder in which the add-on of LEV to a conventional treatment regimen improved symptoms of depression, as well as those of mania/mixed mania, and disrupted the severe rapid cycling pattern.

The neurobiology and control of anxious states

Fear is an adaptive component of the acute "stress" response to potentially-dangerous (external and internal) stimuli which threaten to perturb homeostasis. However, when disproportional in intensity, chronic and/or irreversible, or not associated with any genuine risk, it may be symptomatic of a debilitating anxious state: for example, social phobia, panic attacks or generalized anxiety disorder. In view of the importance of guaranteeing an appropriate emotional response to aversive events, it is not surprising that a diversity of mechanisms are involved in the induction and inhibition of anxious states. Apart from conventional neurotransmitters, such as monoamines, gamma-amino-butyric acid (GABA) and glutamate, many other modulators have been implicated, including: adenosine, cannabinoids, numerous neuropeptides, hormones, neurotrophins, cytokines and several cellular mediators. Accordingly, though benzodiazepines (which reinforce transmission at GABA(A) receptors), serotonin (5-HT)(1A) receptor agonists and 5-HT reuptake inhibitors are currently the principle drugs employed in the management of anxiety disorders, there is considerable scope for the development of alternative therapies. In addition to cellular, anatomical and neurochemical strategies, behavioral models are indispensable for the characterization of anxious states and their modulation. Amongst diverse paradigms, conflict procedures--in which subjects experience opposing impulses of desire and fear--are of especial conceptual and therapeutic pertinence. For example, in the Vogel Conflict Test (VCT), the ability of drugs to release punishment-suppressed drinking behavior is evaluated. In reviewing the neurobiology of anxious states, the present article focuses in particular upon: the multifarious and complex roles of individual modulators, often as a function of the specific receptor type and neuronal substrate involved in their actions; novel targets for the management of anxiety disorders; the influence of neurotransmitters and other agents upon performance in the VCT; data acquired from complementary pharmacological and genetic strategies and, finally, several open questions likely to orientate future experimental- and clinical-research. In view of the recent proliferation of mechanisms implicated in the pathogenesis, modulation and, potentially, treatment of anxiety disorders, this is an opportune moment to survey their functional and pathophysiological significance, and to assess their influence upon performance in the VCT and other models of potential anxiolytic properties.

Effects of gabapentin on anxiety induced by simulated public speaking

The effects of gabapentin, 400 mg and 800 mg, on anxiety induced by simulated public speaking (SPS) were investigated. Thirty-two normal male volunteers (aged 17-30 years) had their anxiety and mood evaluated by self-scales [Visual Analogue Mood Scale (VAMS) and Profile of Mood State (POMS)] during the SPS procedure. Physiological measures (heart rate and blood pressure) were taken. Treatment with gabapentin at 800 mg attenuated the anxiety of subjects that had a decrease on the VAMS item calm-excite. In addition, volunteers that received gabapentin at 400 mg and 800 mg showed a decrease in the hostility score in POMS. Our results suggest, in agreement with other studies, an anxiolytic potential to gabapentin.

Treatment of bipolar depression: current status, continued challenges, and the STEP-BD approach

Even though at least 10% (if not 20%) of those who experience a first lifetime episode of depression will subsequently develop bipolar disorder, the alliance of academic and industry research agendas that leads to developing and testing new antidepressants has failed to produce a sufficient knowledge base. It is therefore impossible to apply a truly empirical approach to guide the treatment of people with bipolar depression. Consequently, there are holes in contemporary evidenced-based practice guidelines large enough to drive a truck through; furthermore, there are some recommendations that have no factual basis other than expert opinion. However, with new research emerging on lamotrigine and olanzapine, in addition to the pending results of larger studies supported by the National Institute of Mental Health and the Stanley Foundation, there is evidence that some progress is being made.

Combination treatment in bipolar disorder: a review of controlled trials

OBJECTIVES

Monotherapy is often inadequate and combination drug regimens have become the norm for the treatment of bipolar disorder. Virtually all classes of psychotropic drugs have been used in bipolar disorder in combination for a variety of indications. This article reviews the available published data from controlled, blinded studies regarding combination treatments in the different treatment phases of bipolar disorder.

METHODS

Articles for this review were obtained from a search of the Medline database (1966-2002), using the following keywords and phrases: add-on, antipsychotic, anticonvulsant, antidepressant, combination treatment, lithium, neuroleptic, and polypharmacy. The search was augmented by data presented at scientific meetings. Data included in this article were only from controlled studies that evaluated combinations of two or more agents.

RESULTS

For acute mania, the most useful combination treatments as determined by controlled studies, appear to be an antipsychotic drug with a mood-stabilizer. The combination of lithium and valproate, even though widely used for acute mania, is lacking in controlled data. For acute bipolar depression, the controlled combination studies reviewed fail to show clear advantages in efficacy of an antidepressant with a mood-stabilizer versus two stabilizers or a mood-stabilizer alone. Large, controlled, randomized, long-term studies with modern antidepressants are not available. Controlled combination studies of mood-stabilizers suggest gains in efficacy over monotherapy in the long-term treatment of bipolar disorder.

CONCLUSIONS

Controlled combination studies in bipolar disorder are uncommon. Increased attention should be given to study combination treatments in all phases of bipolar illness to determine the most efficacious and safest combinations.

Activation of glutamate neurotransmission in the prefrontal cortex sustains the motoric and dopaminergic effects of phencyclidine

N-methyl-D-aspartate (NMDA) receptor antagonists such as phencyclidine (PCP) produce schizophrenia-like symptoms in healthy individuals, thus generating interest in understanding the mechanisms by which these drugs modify behavior. The hallmark of the behavioral effects of NMDA antagonists in the rodent is stereotyped motor activity. Although the major cellular correlate of this behavioral activation is thought to be an increase in dopamine neurotransmission in the nucleus accumbens (NAc), recent evidence suggests that NAc dopamine is neither necessary nor sufficient to elicit NMDA antagonist-induced motor effects. Based on our previous observation that NMDA antagonists increase glutamate efflux in the prefrontal cortex (PFC), and thus increase non-NMDA receptor glutamatergic neurotransmission in this region, we hypothesized that an increase in PFC efferent activity would activate motor pathways, independent of dopamine neurotransmission in the NAc. We tested this hypothesis by measuring dopaminergic and motoric effects of PCP while blocking non-NMDA receptors in the PFC, or in the ventral tegmental area (VTA) and NAc. Both VTA and NAc receive direct glutamatergic input from the PFC, and are implicated in the regulation of motor behavior. Blocking non-NMDA receptors in the PFC, NAc, or the VTA inhibited PCP-induced locomotion and stereotypy. This blockade was accompanied by an inhibition of PCP's effect on cortical dopamine release. However, the PCP-induced increase in NAc dopamine was not diminished, despite the behavioral inhibition. These findings suggest that the PFC may be a principal site for the regulation of PCP-induced stereotypy and hyperlocomotion, and that this regulation is independent of accumbal dopamine activity.

Transtorno de estresse pós-traumático e transtorno de humor bipolar

O Transtorno Bipolar (THB) não é somente uma condição endógena. Severos eventos negativos durante a vida influenciam o desenvolvimento do primeiro episódio e alteram o curso do THB durante a vida. O Transtorno de Estresse Pós-Traumático (TEPT) é uma severa e incapacitante doença mental que afeta uma significativa parcela da população, em algum momento de suas vidas. A presença concomitante de TEPT e THB parece mais freqüente que anteriormente sugerido, e pacientes psicóticos com história de trauma tem sintomas mais severos e maior tendência a abusar de substância psicoativas ilícitas. Pensamentos intrusivos e pesadelos ocorrem com freqüência nos pacientes com TEPT e têm sido associados aos transtornos de humor. O tratamento farmacológico dessa comorbidade ainda está relacionado a estudo empíricos ou não-controlados. Neste artigo, são revisados aspectos atuais relacionados a essa comorbidade e enfatizados aspectos referentes à epidemiologia, etiologia, curso e tratamento farmacológico da comorbidade entre TEPT e THB. Especialmente, este estudo enfatiza a importância de avaliar sistematicamente a história de trauma em pacientes com THB.

Gabapentin in geriatric mania

There is little available information on anticonvulsant treatment of mania in elderly patients. Seven elderly patients, each in a manic episode, were treated with gabapentin. All 7 patients experienced improvement in manic symptoms, with minimal to no side effects. They received gabapentin in combination with antipsychotic medications, and in 1 case in combination with valproate. Gabapentin appears to be a safe and effective treatment in geriatric mania when combined with antipsychotic medications or valproate. Gabapentin appears to be well tolerated with no major adverse drug interactions or side effects in elderly manic patients. This case series suggests that controlled studies are warranted to examine gabapentin's efficacy and side effects, particularly as an adjunctive medication, in geriatric mania.

Acute antimanic efficacy and safety of intravenous valproate loading therapy: an open-label study

This open-label study investigated whether acute antimanic effects and safety of intravenous valproate loading therapy is superior to oral valproate loading. Eighteen patients with DSM-IV diagnosis of either bipolar affective disorder or schizomania who met the study criteria were recruited (9 in the intravenous and 9 in the oral valproate group). Psychopathology was assessed with the scale for manic and mixed states on days 0 and 4. A checklist was used for the assessment of side effects. The results showed about 36% reduction in total mean manic scores with intravenous valproate loading; however, statistically, the degree of reduction in manic scores was comparable between the groups. A nonsignificant increase in the rate of adverse events was noted in the intravenous group. Despite its limitations, this study suggests that acute antimanic effects of both intravenous and oral valproate loading are comparable.

A1 receptor and adenosinergic homeostatic regulation of sleep-wakefulness: effects of antisense to the A1 receptor in the cholinergic basal forebrain

We hypothesized that adenosine, acting via the A1 receptor, is a key factor in the homeostatic control of sleep. The increase in extracellular levels of adenosine during prolonged wakefulness is thought to facilitate the transition to sleep by reducing the discharge activity of wakefulness-promoting neurons in the basal forebrain. Adenosine A1 receptor control of the homeostatic regulation of sleep was tested by microdialysis perfusion of antisense oligonucleotides against the mRNA of the A1 receptor in the magnocellular cholinergic region of the basal forebrain of freely behaving rats. After microdialysis perfusion of A1 receptor antisense in the basal forebrain, spontaneous levels of sleep-wakefulness showed a significant reduction in non-rapid eye movement (REM) sleep with an increase in wakefulness. After 6 hr of sleep deprivation, the antisense-treated animals spent a significantly reduced amount of time in non-REM sleep, with postdeprivation recovery sleep hours 2-5 showing a reduction of approximately 50-60%. There was an even greater postdeprivation reduction in delta power (60-75%) and a concomitant increase in wakefulness. All behavioral state changes returned to control (baseline) values after the cessation of antisense administration. Control experiments with microdialysis perfusion of nonsense (randomized antisense) oligonucleotides and with artificial CSF showed no effect during postdeprivation recovery sleep or spontaneously occurring behavioral states. Antisense to the A1 receptor suppressed A1 receptor immunoreactivity but did not show any neurotoxicity as visualized by Fluoro-Jade staining. These data support our hypothesis that adenosine, acting via the A1 receptor, in the basal forebrain is a key component in the homeostatic regulation of sleep.

Kappa-opioid receptor-mediated enhancement of the hyperpolarization-activated current (I(h)) through mobilization of intracellular calcium in rat nucleus raphe magnus

The hyperpolarization-activated current (Ih) is important in the control of resting membrane potential, in the regulation of network firing pattern and in the modulation of presynaptic transmitter release in central neurons. Recent studies on native and cloned Ih channels have demonstrated that the Ih channel is commonly modulated by cAMP through a positive shift in its voltage dependence without a change in its maximum current. The present study demonstrates that activation of kappa-opioid receptors enhances Ih by increasing its maximum current in brainstem neurons in the nucleus raphe magnus. Agents that interfere with the release of intracellular calcium from calcium stores altered the maximum Ih and significantly attenuated the kappa-receptor-mediated enhancement of Ih. These results suggest that kappa-opioid receptors enhance the maximum Ih by mobilizing intracellular calcium from calcium stores. This provides a physiological function for kappa-receptor-stimulated calcium release and may suggest another Ih-regulating mechanism by intracellular calcium in central neurons.

Topiramate in the treatment of severe bulimia nervosa with comorbid mood disorders: a case series

OBJECTIVE

To report observations on the efficacy and tolerability of topiramate in a sample of five patients with severe symptoms of bulimia nervosa and comorbid mood and/or anxiety disorders.

METHOD

Topiramate was added to other psychotropic medication under open-label conditions up to the maximum tolerated dose or until remission of the eating disorder was achieved.

RESULTS

Topiramate almost completely eliminated binging and purging behavior in three of the five patients. Improvement was maintained throughout the period of follow-up for up to 18 months. One patient showed a partial, temporary response, and the fifth was intolerant of the drug and unable to complete an adequate trial.

DISCUSSION

These results suggest strongly that the efficacy of topiramate in patients with bulimia nervosa with and without comorbid mood and anxiety disorders should be investigated more fully.

Mechanistic stratification of antineuralgic agents

Current treatment options in neuropathic pain include antidepressants, antiepileptics, antiarrhythmics, and analgesics. However, stratification of treatments based on their original therapeutic class is inadequate, as drugs belonging to a particular class may have distinct antineuralgic modes of action. It is therefore useful to review the mechanisms of action of these drugs and determine which of these mechanisms is most likely responsible for the drugs' efficacy in the symptomatic treatment of neuropathic pain. Switching from the traditional therapeutic class stratification to one based on putative antineuralgic mechanisms of action will allow more rational selection of therapies, and aid evaluation of the additive or synergistic effects of drugs when used in combination.

Epidemiology, implications and mechanisms underlying drug-induced weight gain in psychiatric patients

Body weight gain frequently occurs during drug treatment of psychiatric disorders and is often accompanied by increased appetite or food craving. While occurrence and time course of this side effect are difficult to predict, it ultimately results in obesity and the morbidity associated therewith in a substantial part of patients, often causing them to discontinue treatment even if it is effective. This paper reviews the available epidemiological data on the frequency and extent of weight gain associated with antidepressant, mood-stabilizing, and antipsychotic treatment. Possible underlying pathomechanisms are discussed with special attention to central nervous control of appetite including the role of leptin and the tumor necrosis factor system. Metabolic alterations induced by drug treatment such as type 2 diabetes mellitus and the metabolic syndrome are also considered. Weight gain appears to be most prominent in patients treated with some of the second generation antipsychotic drugs and with some mood stabilizers. Marked weight gain also frequently occurs during treatment with most tricyclic antidepressants, while conventional antipsychotics typically induce only slight to moderate weight gain. Serotonin reuptake inhibitors may induce weight loss during the first few weeks, but some of them induce weight gain during long-term treatment. Several antidepressant and antipsychotic drugs are identified which reliably do not cause weight gain or even reduce weight. Based on these insights, countermeasures to manage drug-induced weight gain are suggested.

When do antidepressants worsen the course of bipolar disorder?

Bipolar disorder may be more prevalent than previously believed. Because a substantial number of patients with bipolar disorder present with an index depressive episode, it is likely that many are misdiagnosed with unipolar major depression. Even if a correct diagnosis is made, depressive symptoms in bipolar disorder are notoriously difficult to treat. Patients are often treated with antidepressants, which, if used improperly, are known to induce mania and provoke rapid cycling. This article explores diagnostic conundrums in bipolar depression and their possible solutions, based on current research evidence. It also elucidates current evidence regarding the risks and benefits associated with antidepressant use and evaluates alternative treatment regimens for the depressed bipolar population, including the use of traditional mood stabilizers such as lithium, novel anticonvulsants such as lamotrigine, and atypical antipsychotics.

Advances in the pharmacologic treatment of bipolar depression

The pharmacologic treatment of bipolar depression has not been well studied in randomized, controlled trials. Thus important clinical questions regarding the efficacy in bipolar depression of mood stabilizers, antidepressants, and new antiepileptic and atypical antipsychotic agents have been relatively unaddressed. Until recently there were few data regarding the degree to which mood stabilizers reduce the risk of switching associated with antidepressant treatment. Likewise, although treatment guidelines have often recommended limiting antidepressant exposure in the maintenance treatment of bipolar depression, the potential risks of depressive relapse after antidepressant discontinuation were largely unknown. We review here data from new randomized, controlled trials published or presented during the past 5 years regarding the efficacy of antidepressants, mood stabilizers, lamotrigine, and olanzapine in the acute and maintenance treatment of bipolar depression. We also review new studies clarifying the protective effect of coadministration of mood stabilizers from antidepressant-associated switching and the risk of depressive relapse when antidepressants are discontinued during maintenance treatment.

Therapeutic potential of kava in the treatment of anxiety disorders

Anxiety disorders are among the most common psychiatric disorders that affect all age groups of the general population. Currently, the preferred treatment is with pharmacological drugs that have antidepressant or anti-anxiety properties. However, these agents have numerous and often serious adverse effects, including sedation, impaired cognition, ataxia, aggression, sexual dysfunction, tolerance and dependence. Withdrawal reactions on termination after long-term administration are also a major limiting factor in the use of these agents. Herbal remedies, including kava (Piper methysticum), have been shown to be effective as alternative treatments, at least in mild to moderate cases of anxiety. Kava is a social and ceremonial herb from the South Pacific. It is available in the west as an over-the-counter preparation. Its biological effects, due to a mixture of compounds called kavalactones, are reported to include sedative, anxiolytic, antistress, analgesic, local anaesthetic, anticonvulsant and neuroprotective properties. The pharmacological properties of kava are postulated to include blockade of voltage-gated sodium ion channels, enhanced ligand binding to gamma-aminobutyric acid (GABA) type A receptors, diminished excitatory neurotransmitter release due to calcium ion channel blockade, reduced neuronal reuptake of noradrenaline (norepinephrine), reversible inhibition of monoamine oxidase B and suppression of the synthesis of the eicosanoid thromboxane A(2), which antagonises GABA(A) receptor function. Clinical studies have shown that kava and kavalactones are effective in the treatment of anxiety at subclinical and clinical levels, anxiety associated with menopause and anxiety due to various medical conditions. Until recently, the adverse effects attributed to kava use were considered mild or negligible, except for the occurrence of a skin lesion. This disorder, called kava dermopathy, occurs only with prolonged use of large amounts of kava and is reversible on reduced intake or cessation. Rare cases of interactions have occurred with pharmaceutical drugs that share one or more mechanisms of action with the kavalactones. In the past few years, about 35 cases of severe liver toxicity associated with kava intake have been reported in Europe and the US. However, a direct causal relationship with kava use has been difficult to establish in the majority of the cases, and there is insufficient evidence to implicate kava as the responsible agent. Nevertheless, until further research clarifies any causality, kava should be used with caution.

Antidepressant properties of anticonvulsant drugs for bipolar disorder

A growing number of anticonvulsant drugs are receiving attention as possible mood stabilizers. This attention is based mainly on the assumption that the antimanic efficacy of anticonvulsants makes them suitable as mood stabilizers. However, their antidepressant properties have received less scrutiny. In this review, current evidence concerning the acute and prophylactic efficacy of divalproex, carbamazepine, gabapentin, lamotrigine, and topiramate in bipolar depression is evaluated. Clinical outcome data are considered, together with limitations of existing studies and the concept of unmet clinical needs. Findings in placebo-controlled trials suggest an acute and prophylactic antidepressant effect with lamotrigine monotherapy and more modest antidepressant benefits with other agents administered as monotherapies. Results of published studies are considered with respect to the conceptualization of mood stabilization as arising from antimanic and antidepressant efficacy in bipolar disorder.

Bipolar depression: management options

Bipolar depression is the predominant abnormal mood state in bipolar disorder. However, despite the key pertinence of this phase of the condition, the focus of research and indeed of clinical interest in the management of bipolar disorder has been mainly on mania. Bipolar depression has been largely neglected, and early studies often failed to distinguish depression due to major unipolar depression from that due to bipolar disorder. Consequently, many treatments used in the management of major depression have been adopted for use in bipolar depression without any robust evidence of efficacy. The selective serotonin reuptake inhibitors (SSRIs), bupropion, tricyclic antidepressants and monoamine oxidase inhibitors are all effective antidepressants in the management of bipolar depression. They are all associated with a small risk of antidepressant-induced mood instability. The mood stabilisers lithium, carbamazepine and valproate semisodium (divalproex sodium) all appear to have modest acute antidepressant properties. Among these, lithium is supported by the strongest data, but the use of lithium in the treatment of bipolar depression as a monotherapeutic agent is limited by its slow onset of action. Recently, there has been a growing body of evidence suggesting that lamotrigine may have particular effectiveness in both the acute and prophylactic management of bipolar depression. Clinical management of bipolar depression involves various combinations of antidepressants and mood stabilisers and is partly determined by the context in which the depressive episode occurs. In general, 'de novo' and 'breakthrough' (where the patient is already receiving medication) bipolar depression may be successfully managed by initiating mood stabiliser monotherapy, to which an antidepressant or second mood stabiliser may be added at a later date, if necessary. Breakthrough episodes of bipolar depression occurring in patients receiving combination therapy (two mood stabilisers or a mood stabiliser plus an antidepressant) require either switching of ongoing medications or further augmentation. If this fails, then novel strategies or ECT should be considered. Bipolar depression is a disabling illness and the predominant mood state for the vast majority of those with bipolar disorder. It therefore warrants prompt management once suitably diagnosed, especially as it is associated with a considerable risk of suicide and in the majority of instances is eminently treatable.

Substance P and Substance P receptor antagonists in the pathogenesis and treatment of affective disorders

Substance P (SP) is a neuropeptide which is widely distributed in the periphery and the central nervous system (CNS), where it is co-localised with other neurotransmitters such as serotonin or dopamine and where it acts as a neuromodulator. SP has been proposed to play a role in the aetiopathology of asthma, inflammatory bowel disease, emesis, psoriasis, as well as neuropsychiatric disorders including pain syndromes (e.g. migraine and fibromyalgia) and affective disorders, anxiety disorders, schizophrenia and Alzheimer's disease. This review focuses on the role of SP in the pathogenesis of affective disorders. It summarises the current knowledge on measurements of SP in the CSF and serum in patients with depressive disorders or fibromyalgia, effects of SP-application in humans, SP-receptor expression in postmortem brains and the modulation of SP levels in the course of antidepressant treatment. It also discusses the promise of substance P-receptor antagonists (SPA) for the treatment of affective disorders and their proposed mechanism of action. In summary, much more research is needed to elucidate the role of SP in the pathogenesis of depression. SPA are promising as future drugs for the treatment of affective disorders, but current clinical trials have yet to be completed to draw a firm conclusion. Key words: substance P, neurokinin1-receptor, affective disorders, depression, review.

Bipolar depression: criteria for treatment selection, definition of refractoriness, and treatment options

OBJECTIVE

This paper reviews controlled studies of bipolar depression, outlines criteria for choosing treatment, defines refractoriness in bipolar depression, and provides options for treatment of refractory bipolar depression.

METHODS

Controlled studies that examined the efficacy of treatments for acute and long-term treatment of bipolar depression were located through electronic searches of several databases and by manual crosssearch of references and proceedings of international meetings.

RESULTS

Lithium comes close to fulfilling the proposed criteria for first-line treatment for bipolar depression, and those not responding to lithium should be considered to have refractory bipolar depression. Options for such patients include addition of lamotrigine or a second mood stabilizer, or a newer-generation antidepressant such as a serotonin re-uptake inhibitor or bupropion, or the atypical antipsychotic olanzapine.

CONCLUSIONS

Although there is a paucity of research in the treatment of refractory bipolar depression, available data could be used for providing rational treatment options for such patients. However, further studies are urgently needed to determine which options are most appropriate for which type of patients.

A placebo-controlled, cross-over trial of lamotrigine in depersonalization disorder

There is evidence to support the view that glutamate hyperactivity might be relevant to the neurobiology of depersonalization. We tested the efficacy of lamotrigine, which reduces glutamate release, as a treatment for patients with depersonalization disorder. A double-blind, placebo-controlled, cross-over design was used to evaluate 12 weeks of treatment of lamotrigine. Subjects comprised nine patients with DSM-IV depersonalization disorder. Changes on the Cambridge Depersonalization Scale and the Present State Examination depersonalization/derealization items were compared across the two cross-over periods. Lamotrigine was not significantly superior to placebo. None of the nine patients was deemed a responder to the lamotrigine arm of the cross-over. Lamotrigine does not seem to be useful as a sole medication in the treatment of depersonalization disorder.

Morphine tolerance and reward but not expression of morphine dependence are inhibited by the selective glutamate carboxypeptidase II (GCP II, NAALADase) inhibitor, 2-PMPA

Inhibition of glutamate carboxypeptidase II (GCP II; NAALADase) produces a variety of effects on glutamatergic neurotransmission. The aim of this study was to investigate effects of GCP II inhibition with the selective inhibitor, 2-PMPA, on: (a) development of tolerance to the antinociceptive effects, (b) withdrawal, and (c) conditioned reward produced by morphine in C57/Bl mice. The degree of tolerance was assessed using the tail-flick test before and after 6 days of twice daily (b.i.d.) administration of 2-PMPA and 10 mg/kg of morphine. Opioid withdrawal was measured 3 days after twice daily morphine (30 or 10 mg/kg) administration, followed by naloxone challenge. Conditioned morphine reward was investigated using conditioned place preference with a single morphine dose (10 mg/kg). High doses of 2-PMPA inhibited the development of morphine tolerance (resembling the effect of 7.5 mg/kg of the NMDA receptor antagonist, memantine) while not affecting the severity of withdrawal. A high dose of 2-PMPA (100 mg/kg) also significantly potentiated morphine withdrawal, but inhibited both acquisition and expression of morphine-induced conditioned place preference. Memantine inhibited the intensity of morphine withdrawal as well as acquisition and expression of morphine-induced conditioned place preference. In addition, 2-PMPA did not affect learning or memory retrieval in a simple two-trial test, nor did it produce withdrawal symptoms in morphine-dependent, placebo-challenged mice. Results suggest involvement of GCP II (NAALADase) in phenomena related to opioid addiction.

Lamotrigine augmentation in unipolar depression

A significant number of patients with unipolar depression fail to achieve remission after one or a series of antidepressants. We present the results of a retrospective chart review of the efficacy and tolerability of lamotrigine as an augmentation drug in treatment-resistant unipolar depression. A previous absence of a response was defined as the clinically significant presence of depressive symptomatology after 6 weeks of treatment with an antidepressant, with at least 3 weeks at the maximum dose tolerated by the patient. The patients were rated retrospectively using the Clinical Global Impression rating scale. Seventy-six percent of the patients improved. Gender, age, basal severity of the episode and degree of previous non response were not statistically significantly associated with response to lamotrigine augmentation. Comorbidity showed a tendency to be negatively related with response to lamotrigine. Three patients abandoned the treatment with lamotrigine due to side-effects. Complaints were excessive somnolence, headache, dizziness, nausea and malaise. Data suggest that lamotrigine is a promising drug for treatment-refractory unipolar depression. Double-blind studies are necessary to confirm its use as an augmentation agent.

Is there a link between atypical and early-onset "unipolar" depression and bipolar II disorder?

The aim of the present study was to determine whether there is a link between "unipolar" depression with atypical features and early onset, and bipolar II disorder, using atypical features and early onset as markers of bipolarity. A total of 158 consecutive unipolar and 234 bipolar II major depressive episode (MDE) outpatients were interviewed using the Structured Clinical Interview for DSM-IV (SCID). Patients were divided into those with and without atypical features, and into those with and without early onset. Comparisons were made on variables reported to distinguish bipolar from unipolar: age of onset, recurrences, atypical features, depressive mixed state (MDE plus three or more concurrent hypomanic symptoms [DMX3]), and bipolar II family history. Compared to bipolar II patients, patients with atypical unipolar were not significantly different regarding age of onset, DMX3, recurrences, and bipolar II family history. Compared to non-atypical unipolar patients, atypical unipolar patients had a significantly different age of onset. Nonatypical unipolar patients, versus bipolar II patients, were significantly different regarding age of onset, recurrences, DMX3, and bipolar II family history. Early onset unipolar, versus bipolar II, were not significantly different regarding atypical features, recurrences, DMX3, and bipolar II family history. Later onset unipolar patients, versus bipolar II patients, were significantly different regarding atypical features, recurrences, DMX3, and bipolar II family history. These results support a link of atypical and early-onset "unipolar" depression with bipolar II disorder, and support Pages and Dunner's suggestion to combine bipolar II and recurrent unipolar into a single group.

NMDA receptor-mediated extracellular adenosine accumulation in rat forebrain neurons in culture is associated with inhibition of adenosine kinase

The effect of N-methyl-d-aspartate (NMDA) on regulation of extracellular adenosine was investigated in rat forebrain neurons in culture. NMDA evoked accumulation of extracellular adenosine with an EC50 value of 4.8 +/- 1.2 microM. The effect of NMDA was blocked by (+)-5-methyl-10,11-dihydro-5H-dibenzo [a, d] cyclohepten-5,10-imine hydrogen maleate indicating that NMDA receptor activation was involved. The NMDA effect was also blocked by chelation of extracellular Ca2+ indicating that influx of calcium was required. The nitric oxide-cyclic GMP signalling pathway was not involved, as nitric oxide synthase inhibitors were unable to block, and cGMP analogs were unable to mimic, the effect of NMDA. The source for extracellular adenosine was likely to be intracellular adenosine as the ecto-5'-nucleotidase inhibitor alpha beta-methylene-ADP was unable to block the effect of NMDA. One possible cause of intracellular adenosine accumulation might be NMDA receptor-mediated inhibition of mitochondrial function and ATP hydrolysis. We found that NMDA caused a concentration dependent depletion of intracellular ATP with an EC50 value of 21 +/- 8 microM. NMDA also caused a significant decrease in adenosine kinase activity, assayed by two different methods. Consistent with the hypothesis that inhibition of adenosine kinase is sufficient to cause an increase in extracellular adenosine, inhibition of adenosine kinase by 5'-iodotubercidin resulted in elevation of extracellular adenosine. However, in the presence of a concentration of 5'-iodotubercidin that inhibited over 90% of adenosine kinase activity, exposure to NMDA still caused adenosine accumulation. These studies suggest that several possible mechanisms are likely to be involved in NMDA-evoked extracellular adenosine accumulation.

Brain-immune interactions in sleep

This chapter discusses various levels of interactions between the brain and the immune system in sleep. Sleep-wake behavior and the architecture of sleep are influenced by microbial products and cytokines. On the other hand, sleep processes, and perhaps also specific sleep states, appear to promote the production and/or release of certain cytokines. The effects of immune factors such as endotoxin and cytokines on sleep reveal species specificity and usually strong dependence on parameters such as substance concentration, time relative to administration or infection with microbial products, and phase relation to sleep and/or the light-dark cycle. For instance, endotoxin increased SWS and EEG SWA in humans only at very low concentrations, whereas higher concentrations increased sleep stage 2 only, but not SWS. In animals, increases in NREM sleep and SWA were more consistent over a wide range of endotoxin doses. Also, administration of pro-inflammatory cytokines such as IL-6 and IFN-alpha in humans acutely disturbed sleep while in rats such cytokines enhanced SWS and sleep. Overall, the findings in humans indicate that strong nonspecific immune responses are acutely linked to an arousing effect. Although subjects feel subjectively tired, their sleep flattens. However, some observations indicate a delayed enhancing effect on sleep which could be related to the induction of secondary, perhaps T-cell-related factors. This would also fit with results in animals in which the T-cell-derived cytokine IL-2 enhanced sleep while cytokines with immunosuppressive functions like IL-4 and L-10 suppressed sleep. The most straightforward similarity in the cascade of events inducing sleep in both animals and humans is the enhancing effect of GHRH on SWS, and possibly the involvement of the pro-inflammatory cytokine systems of IL-1 beta and TNF-alpha. The precise mechanisms through which administered cytokines influence the central nervous system sleep processes are still unclear, although extensive research has identified the involvement of various molecular intermediates, neuropeptides, and neurotransmitters (cp. Fig. 5, Section III.B). Cytokines are not only released and found in peripheral blood mononuclear cells, but also in peripheral nerves and the brain (e.g., Hansen and Krueger, 1997; März et al., 1998). Cytokines are thereby able to influence the central nervous system sleep processes through different routes. In addition, neuronal and glial sources have been reported for various cytokines as well as for their soluble receptors (e.g., Kubota et al., 2001a). Links between the immune and endocrine systems represent a further important route through which cytokines influence sleep and, vice versa, sleep-associated processes, including variations in neurotransmitter and neuronal activity may influence cytokine levels. The ability of sleep to enhance the release and/or production of certain cytokines was also discussed. Most consistent results were found for IL-2, which may indicate a sleep-associated increase in activity of the specific immune system. Furthermore, in humans the primary response to antigens following viral challenge is enhanced by sleep. In animals results are less consistent and have focused on the secondary response. The sleep-associated modulation in cytokine levels may be mediated by endocrine parameters. Patterns of endocrine activity during sleep are probably essential for the enhancement of IL-2 and T-cell diurnal functions seen in humans: Whereas prolactin and GH release stimulate Th1-derived cytokines such as IL-2, cortisol which is decreased during the beginning of nocturnal sleep inhibits Th1-derived cytokines. The immunological function of neurotrophins, in particular NGF and BDNF, has received great interest. Effects of sleep and sleep deprivation on this cytokine family are particularly relevant in view of the effects these endogenous neurotrophins can have not only on specific immune functions and the development of immunological memories, but also on synaptic reorganization and neuronal memory formation.

Different effects of phencyclidine and methamphetamine on firing activity of medial prefrontal cortex neurons in freely moving rats

The purpose of this study was to compare the effects of systemically administered MAP with those of phencyclidine (PCP), both of which induced comparable locomotor activity, on firing activity of medial prefrontal cortex (mPFC) neurons in freely moving rats. The results show that, unlike PCP, acutely administered MAP produced little changes in firing activity of mPFC neurons.

Functional analysis of the deficit in semantic context processes in schizophrenic patients: an event-related potentials study

AIM

Schizophrenic patients exhibit a deficit in the semantic context processing strategies which might be responsible for the language and communication disorders that are characteristic of this condition. The aim of our study was to identify the nature of the contextualization processes which are lacking in schizophrenic patients, by distinguishing between processes for the generation of expectations and processes of semantic integration.

PATIENTS AND METHOD

Thirteen schizophrenic patients and 12 healthy controls performed two tasks: (a) a lexical decision task (LDT) with a highly structured sentence context and whose experimental characteristics made it possible to call strongly on predictive strategies, and (b) a LDT with classic semantic priming (the context being reduced to a single word). In this latter task, the small number of related words did not prompt the generation of expectations but instead called on the postlexical integration process. The event-related potentials (ERP) were recorded during the administration of the task.

RESULTS AND CONCLUSION

In the sentence task, we observed a modulation in the N400 amplitude due to the presence of expectations both in the schizophrenic and control participants: predictable words evoked a small N400 amplitude compared to the non-predictable words. In contrast, in the simple (priming) task, the semantic link evoked an N400 amplitude modulation in the control group exclusively. Our results indicate that schizophrenics could be able to use context to activate expectations for the most highly predictable item, and that their deficit appears when the processing strategy is based on the integration of the context stored in working memory.

Where the rubber meets the road: The importance of implementation

Phillips & Silverstein argue that a range of cognitive disturbances in schizophrenia result from a deficit in cognitive coordination attributable to NMDA receptor dysfunction. We suggest that the viability of this hypothesis would be further supported by explicit implementation in a computational framework that can produce quantitative estimates of the behavior of both healthy individuals and individuals with schizophrenia.

Local energy depletion in the basal forebrain increases sleep

Sleep saves energy, but can brain energy depletion induce sleep? We used 2,4-dinitrophenol (DNP), a molecule which prevents the synthesis of ATP, to induce local energy depletion in the basal forebrain of rats. Three-hour DNP infusions induced elevations in extracellular concentrations of lactate, pyruvate and adenosine, as well as increases in non-REM sleep during the following night. Sleep was not affected when DNP was administered to adjacent brain areas, although the metabolic changes were similar. The amount and the timing of the increase in non-REM sleep, as well as in the concentrations of lactate, pyruvate and adenosine with 0.5-1.0 mM DNP infusion, were comparable to those induced by 3 h of sleep deprivation. Here we show that energy depletion in localized brain areas can generate sleep. The energy depletion model of sleep induction could be applied to in vitro research into the cellular mechanisms of prolonged wakefulness.