Clinical features associated with early drop-out among outpatients with unipolar and bipolar depression

Drop-out from follow-up visits carries significant burden for people diagnosed with depression. The present study assesses multiple clinical moderators of drop-out among depressed outpatients. We retrospectively followed-up 131 outpatients over 6 months: 78 major depressive disorder (MDD), and 53 bipolar disorder (BD-I = 24; BD-II = 29) patients diagnosed according to the Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition. Participants were assessed with standard rating scales administered by experienced psychiatrists. Upon descriptive and Cox regression analyses, 17/53 BDs (32%) dropped-out; the overall survival time until drop-out was 57.94 ± 17.79 days. BD drop-outs were younger, had an earlier age at onset, shorter illness duration, lower rates of lifetime obsessive-compulsive disorder/suicidal behavior, higher rates of substance use disorder (SUD), anxious and mixed features of depression compared to BDs attending up to six months. Among MDD patients, 10/78 cases (13%) dropped-out by month-6 with an average survival of 42.40 ± 16.45 days. Earlier age of onset, younger age, positive family history for mood disorders, lower rates of lifetime generalized anxiety disorder were significantly more frequent among drop-outs than completers, as opposite to SUD, and lifetime recurrent depression. Older age predicted lower drop-out among BDs and MDDs, although with almost null hazard ratio (HR) = 0.928, p < 0.01 vs. HR = 0.941, p < 0.01, respectively. Higher rates of lifetime SUD predicted higher drop-out rates by month-6 among MDDs (HR = 5.477, p = 0.02). Limitations of the study: retrospective design, small sample size, lack of objective measures of treatment-adherence/mood rating during follow-up. Drop-out is common in the real-world setting, warranting specific interventions since the beginning of the treatment.

Predictors of hospitalization length of stay among re-admitted treatment-resistant Bipolar Disorder inpatients

BACKGROUND

Hospitalization accounts for significant health care resource utilization for treatment-resistant Bipolar Disorder (BD), especially among frequent users of acute inpatient psychiatric units. Appraisal of the clinical features and predictive role of selected variables is therefore crucial in such population, representing the aim of the present research.

METHODS

A hundred and nineteen BD inpatients with an established history of pharmacological treatment resistance for either mania or bipolar depression were classified as long hospitalization cases (LOS⁺) and their controls and compared against each other for a number of demographic, clinical, and psychopathological features.

RESULTS

Overall, female sex, current second-generation atypical antipsychotic (SGA)/mood stabilizer other than lithium as well as antidepressant treatment at the admission occurred statistically more frequently among LOS⁺ cases, concordant with higher scores at the Hamilton scales for depression and anxiety. Lithium utilization at the time of hospitalization did not differ between cases and controls (LOS^-, n = 81/119), as predominant affective temperament and other psychopathological rating did not. Overall, the time of admission, use of SGA, anticonvulsant (other than lithium), antidepressant, lifetime alcohol dependence, and BD Type (-I or -II), but not current mood polarity at the time of hospitalization, correctly predicted LOS⁺ grouping 68.2% of the times: Exp(B) = 3.151, p042.

LIMITATIONS

Post-hoc, cross-sectional study, relatively small sample size, recall and selection bias on some diagnoses.

CONCLUSIONS

Overall, LOS⁺ treatment-resistant BD inpatients characterize for higher severity and greater pharmaco-utilization use, which warrants replication studies to include additional predictors to shed further light on the matter.

Dopamine transporter (DAT) genetic hypofunction in mice produces alterations consistent with ADHD but not schizophrenia or bipolar disorder

ADHD, schizophrenia and bipolar disorder are psychiatric diseases with a strong genetic component which share dopaminergic alterations. Dopamine transporter (DAT) genetics might be potentially implicated in all these disorders. However, in contrast to DAT absence, the effects of DAT hypofunction especially in developmental trajectories have been scarcely addressed. Thus, we comprehensively studied DAT hypofunctional mice (DAT+/-) from adolescence to adulthood to disentangle DAT-dependent alterations in the development of psychiatric-relevant phenotypes. From pre-adolescence onward, DAT+/- displayed a hyperactive phenotype, while responses to external stimuli and sensorimotor gating abilities were unaltered. General cognitive impairments in adolescent DAT+/- were partially ameliorated during adulthood in males but not in females. Despite this, attentional and impulsivity deficits were evident in DAT+/- adult males. At the molecular level, DAT+/- mice showed a reduced expression of Homer1a in the prefrontal cortex, while other brain regions as well as Arc and Homer1b expression were mostly unaffected. Amphetamine treatments reverted DAT+/- hyperactivity and rescued cognitive deficits. Moreover, amphetamine shifted DAT-dependent Homer1a altered expression from prefrontal cortex to striatal regions. These behavioral and molecular phenotypes indicate that a genetic-driven DAT hypofunction alters neurodevelopmental trajectories consistent with ADHD, but not with schizophrenia and bipolar disorders.

Palmitoylethanolamide reduces pain-related behaviors and restores glutamatergic synapses homeostasis in the medial prefrontal cortex of neuropathic mice

BACKGROUND

Enhanced supraspinal glutamate levels following nerve injury are associated with pathophysiological mechanisms responsible for neuropathic pain. Chronic pain can interfere with specific brain areas involved in glutamate-dependent neuropsychological processes, such as cognition, memory, and decision-making. The medial prefrontal cortex (mPFC) is thought to play a critical role in pain-related depression and anxiety, which are frequent co-morbidities of chronic pain. Using an animal model of spared nerve injury (SNI) of the sciatic nerve, we assess bio-molecular modifications in glutamatergic synapses in the mPFC that underlie neuropathic pain-induced plastic changes at 30 days post-surgery. Moreover, we examine the effects of palmitoylethanolamide (PEA) administration on pain-related behaviours, as well as the cortical biochemical and morphological changes that occur in SNI animals.

RESULTS

At 1 month, SNI was associated with mechanical and thermal hypersensitivity, as well as depression-like behaviour, cognitive impairments, and obsessive-compulsive activities. Moreover, we observed an overall glutamate synapse modification in the mPFC, characterized by changes in synaptic density proteins and amino acid levels. Finally, with regard to the resolution of pain and depressive-like syndrome in SNI mice, PEA restored the glutamatergic synapse proteins and changes in amino acid release.

CONCLUSIONS

Given the potential role of the mPFC in pain mechanisms, our findings may provide novel insights into neuropathic pain forebrain processes and indicate PEA as a new pharmacological tool to treat neuropathic pain and the related negative affective states. Graphical Abstract Palmitoylethanolamide: a new pharmacological tool to treat neuropathic pain and the related negative affective states.

A role for D-aspartate oxidase in schizophrenia and in schizophrenia-related symptoms induced by phencyclidine in mice

Increasing evidence points to a role for dysfunctional glutamate N-methyl-D-aspartate receptor (NMDAR) neurotransmission in schizophrenia. D-aspartate is an atypical amino acid that activates NMDARs through binding to the glutamate site on GluN2 subunits. D-aspartate is present in high amounts in the embryonic brain of mammals and rapidly decreases after birth, due to the activity of the enzyme D-aspartate oxidase (DDO). The agonistic activity exerted by D-aspartate on NMDARs and its neurodevelopmental occurrence make this D-amino acid a potential mediator for some of the NMDAR-related alterations observed in schizophrenia. Consistently, substantial reductions of D-aspartate and NMDA were recently observed in the postmortem prefrontal cortex of schizophrenic patients. Here we show that DDO mRNA expression is increased in prefrontal samples of schizophrenic patients, thus suggesting a plausible molecular event responsible for the D-aspartate imbalance previously described. To investigate whether altered D-aspartate levels can modulate schizophrenia-relevant circuits and behaviors, we also measured the psychotomimetic effects produced by the NMDAR antagonist, phencyclidine, in Ddo knockout mice (Ddo(-)(/-)), an animal model characterized by tonically increased D-aspartate levels since perinatal life. We show that Ddo(-/-) mice display a significant reduction in motor hyperactivity and prepulse inhibition deficit induced by phencyclidine, compared with controls. Furthermore, we reveal that increased levels of D-aspartate in Ddo(-/-) animals can significantly inhibit functional circuits activated by phencyclidine, and affect the development of cortico-hippocampal connectivity networks potentially involved in schizophrenia. Collectively, the present results suggest that altered D-aspartate levels can influence neurodevelopmental brain processes relevant to schizophrenia.

Opioidergic system and N-methyl D-aspartate receptor (NMDA-R) hypofunction: Translational implications for the pathophysiology of psychosis and drug addiction

Enkephalin is an opioidergic neuromodulator that has been implicated in long-term behavioural sensitization after administration of drugs of abuse. Enkephalin is also a molecular marker of GABAergic neurons in the striato-pallidal pathway that is involved in sensory-motor gating and has been considered dysfunctional in the pathophysiology of psychosis.

In this study we investigated in male Sprague Dawley rats putative changes in Enkephalin transcripts by in situ hybridization after acute or subchronic administration of ketamine in either high or low subanaesthetic doses (50 mg/kg and 12 mg/kg respectively). Ketamine is a non-competitive NMDA-R antagonist that perturbs glutamate neurotransmission and provides a preclinical model of psychosis-like behaviour in rats.

In the acute paradigm the expression of Enkephalin was reduced in the motor, premotor, somatosensory cortices as well as in anterior cingulate. In the subchronic paradigm Enkephalin expression was reduced in the premotor cortex, in the ventromedial caudate-putamen and in the shell of nucleus accumbens. Comparative analysis showed that the relative decrement in gene expression was not significantly different between the acute and subchronic paradigm for each region of interest.

Changes in distribution of Enkephalin expression and correlation analysis of functionally related brain regions suggest that Enkephalin transcripts reduction may be implicated in the motivational aspects of drug addiction and may help explaining some aspects of the pathophysiology in ketamine-induced psychosis.

Dopamine-glutamate interaction and antipsychotics mechanism of action: implication for new pharmacological strategies in psychosis

Schizophrenia is a severe mental illness characterized by behavioral and cognitive symptoms. Several lines of evidence focus on a direct involvement of the glutamatergic system in the pathophysiology of psychosis. The hypofunction of the ionotropic glutamate N-methyl-D-Aspartate Receptor (NMDA-R) has been proposed as a model of schizophrenia in humans. Cortical and subcortical glutamate release seems to be modulated by dopaminergic and, to a lesser extent, serotoninergic circuitries, and tuned by intracellular pathways. Although dopamine D(2) receptor blockade is a crucial mechanism of antipsychotics pharmacodynamic profile, a putative glutamatergic impact of these compounds is suggested by animal pharmacological isomorphisms of psychosis as well as by clinical studies. According to this view, the balance between D(2) antagonism and NMDA-R modulation may be pivotal for the improvement of both positive and negative symptoms. Recently, many pharmacological strategies involving glutamate receptors have been suggested, and novel compounds and pharmacological strategies acting on glutamate transmission are currently under evaluation: i) augmentation strategies improving NMDA-R transmission (glycine, D-serine, D-cycloserine, glycine transporter inhibitors); ii) ampakines, positive modulators of AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptor complex; iii) agonists of glutamate metabotropic receptors; iv) drugs involved in subcellular adaptation both at pre- and post-synaptic sites. Furthermore, molecular markers, suggesting modulation of glutamate circuitries after antipsychotics administration, are an attractive tool to shed more light on glutamate involvement in antipsychotics mechanism of action. In this review we provide a critical update of recent preclinical and clinical data on dopamine-glutamate interaction and its role in new pharmacological strategies for psychosis treatment.

Decreased gene expression of calretinin and ryanodine receptor type 1 in tottering mice

Tottering mice are a spontaneously occurring animal model of human absence epilepsy. They carry a mutation in the P/Q-type calcium channel alpha1A subunit gene which is highly expressed by cerebellar Purkinje cells. In this study, we investigated the role of calretinin and ryanodine receptor type 1 (RyR1) gene expression in the cerebellum of tottering mice. Cerebellar tissue specimens from four experimental groups were processed for in situ hybridization histochemistry (ISHH): (1) wild-type (+/+); (2) heterozygous (tg/+) and two homozygous groups; either (3) without occurrence of an episode of paroxysmal dyskinesia (tg/tg-N); or (4) after an episode of paroxysmal dyskinesia (tg/tg-P) that lasted about 45 min on average. Quantitative analysis showed a statistically significant decrease (p = 0.0001, ANOVA) of calretinin gene expression at the level of the simple lobule of the cerebellum in both homozygous groups compared to the wild-type and heterozygous groups. RyR1 was decreased in the flocculus of the cerebellum in both the tg/tg-N and tg/tg-P groups compared to wild type (p = 0.0174, ANOVA). These results suggest that calretinin gene expression, as well as other genes involved in regulation of calcium homeostasis, such as RyR1, may play a role in the biochemical functional alterations present in tottering mice.

Simian virus-40 large-T antigen binds p53 in human mesotheliomas

We found that simian virus 40 (SV40) induces mesotheliomas in hamsters and that 60% of human mesotheliomas contain and express SV40 sequences, results now confirmed by others [ref. 3-5, and presentations by D. Griffiths & R. Weiss, F. Galateau-SallE, and H.I.P. at "Simian virus 40: A possible human polyoma virus," NIH workshop, 27-28 January 1997, Bethesda, MD (transcript available through SAG Corp., Washington, DC 20008)]. Mesothelioma, an aggressive malignancy resistant to therapy, originates from the serosal lining of the pleural, pericardial and peritoneal cavities. The incidence of mesothelioma continues to increase worldwide because of exposure to crocidolite asbestos. However, at least 20% of mesotheliomas in the United States are not associated with asbestos exposure, and only a minority of people exposed to high concentrations of asbestos develop mesothelioma. Thus, other carcinogens may induce mesothelioma in individuals not exposed to asbestos, and/or may render particular individuals more susceptible to the carcinogenic effect of asbestos. We investigated whether the expression of the SV40 large T-antigen (Tag) interferes with the normal expression of the tumor suppressor gene p53 in human mesotheliomas. We found that SV40 Tag retains its ability to bind and to inactivate p53, a cellular protein that when normally expressed plays an important role in suppressing tumor growth and in inducing sensitivity to therapy. Our findings do not establish a cause-and-effect relation, but indicate that the possibility that SV40 contributes to the development of human mesotheliomas should be carefully investigated.

Quantification of amphetamine-induced changes in [11C]raclopride binding with continuous infusion

Positron emission tomography and single-photon emission computer tomography receptor-binding ligands can be used to measure changes in neurotransmitter levels. In particular, amphetamine-induced dopamine release has been assessed with [11C]raclopride by paired bolus injections and with [123I]iodobenzamide by using a single bolus plus infusion (B/I) study. Here, we measured the change in [11C]raclopride-specific binding in rhesus monkeys after i.v. administration of 0.4 mg/kg amphetamine by using both the bolus and B/I paradigms. Paired bolus studies (control and postamphetamine) were analyzed using compartment modeling and graphical analysis with a new plasma metabolite model to measure the total distribution volume (VT). Specific binding, calculated with three measures linearly proportional to the binding potential, demonstrated a 22-42% reduction in the postamphetamine study. VT values from B/I studies were determined by the tissue-to-plasma ratio at equilibrium, in addition to the bolus methods. There was good agreement between the control VT values between bolus and B/I studies. The amphetamine-induced change in specific binding in B/I studies was 19 +/- 16%, measured directly from tissue radioactivity levels. This study demonstrates that stimulus-induced changes in specific binding can be measured with a single [11C]raclopride study using the B/I method.

Schizophrenia is associated with elevated amphetamine-induced synaptic dopamine concentrations: evidence from a novel positron emission tomography method

A major line of evidence that supports the hypothesis of dopamine overactivity in schizophrenia is the psychomimetic potential of agents such as amphetamine that stimulate dopamine outflow. A novel brain imaging method provides an indirect measure of in vivo synaptic dopamine concentration by quantifying the change in dopamine receptor radiotracer binding produced by agents that alter dopamine release but do not themselves bind to dopamine receptors. The purpose of this investigation is (i) to determine the sensitivity (i.e., amount of dopamine reflected in radiotracer binding changes) of this method by examining the relationship between amphetamine-induced changes in simultaneously derived striatal extracellular dopamine levels with in vivo microdialysis and striatal binding levels with the dopamine D2/D3 positron-emission tomography radioligand [11C]raclopride in nonhuman primates, and (ii) to test the hypothesis of elevated amphetamine-induced synaptic dopamine levels in schizophrenia. In the nonhuman primate study (n = 4), doubling the amphetamine dose produced a doubling in [11C]raclopride specific binding reductions. In addition, the ratio of percent mean dopamine increase to percent mean striatal binding reduction for amphetamine (0.2 mg/kg) was 44:1, demonstrating that relatively small binding changes reflect large changes in dopamine outflow. In the clinical study, patients with schizophrenia (n = 11) compared with healthy volunteers (n = 12) had significantly greater amphetamine-related reductions in [11C]raclopride specific binding (mean +/- SEM): -22.3% (+/-2.7) vs. -15.5% (+/-1.8),P = 0.04, respectively. Inferences from the preclinical study suggest that the patients' elevation in synaptic dopamine concentrations was substantially greater than controls. These data provide direct evidence for the hypothesis of elevated amphetamine-induced synaptic dopamine concentrations in schizophrenia.

Lack of effect of chronic morphine treatment and naloxone-precipitated withdrawal on tyrosine hydroxylase, galanin, and neuropeptide Y mRNA levels in the rat locus coeruleus

Morphine dependence was experimentally induced in rats by daily injection of increasing doses of morphine for seven days. Withdrawal was precipitated in half of the morphine-dependent rats by a single injection of naloxone on day 8. Behavioral signs of withdrawal were evident in the morphine/naloxone group. Gene expression in locus coeruleus (LC) neurons was investigated using quantitative in situ hybridization analysis. Messenger RNA (mRNA) levels for tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis, and for precursors to galanin (GAL) and neuropeptide Y (NPY), peptides that coexist with norepinephrine in LC neurons, were not altered by chronic morphine treatment or naloxone-precipitated withdrawal. In contrast, mRNA levels for c-fos were dramatically elevated in the LC following naloxone-precipitated withdrawal. Chronic morphine treatment caused a small decrease in levels of mRNA encoding the precursor to corticotropin-releasing factor (CRF) in Barrington's nucleus. Although long-term adaptations of LC neurons have previously been implicated in the development of morphine tolerance, dependence, and withdrawal, alterations in the levels of TH, GAL, or NPY mRNA in the LC apparently do not underlie this process.

Ferrous-citrate complex and nigral degeneration: evidence for free-radical formation and lipid peroxidation

Increased nigral iron content in the parkinsonian brain is now well documented and is implicated in the pathogenesis of this movement disorder. Free iron in the pigmented DA-containing neurons catalyze DA autoxidation and Fenton reaction to produce cytotoxic .OH, initiating lipid peroxidation and consequent cell damage. The present results clearly demonstrate that a regional increase in the levels of the "labile iron pool" can result in the degeneration of dopaminergic nigral neurons as reflected by a significant inhibition in the expression of tyrosine hydroxylase mRNA and DA depletion. Iron-complex-induced damage of dopaminergic neurons in the substantia nigra, might have resulted from a sequence of cytotoxic events including the .OH generation and lipid peroxidation as demonstrated in this study. This free-radical-induced oxidative nigral injury may be a reliable free-radical model for studying parkinsonism and may be relevant to idiopathic Parkinson's disease. This apparent nigral injury stimulated by Fe(2+)-citrate is more severe than that produced by ferric iron and its citrate complex. Moreover, these data indicate that Fe(2+)-citrate is as potent as MPP+ in causing oxidative injury to the substantia nigral neurons. However, the nigral toxicity of MPTP and its congeners are not progressive, while Fe(2+)-citrate complex may produce a progressive degeneration of the nigrostriatal neurons which is similar to the progression of ideopathic Parkinson's disease. Thus, this unique Fe(2+)-citrate complex animal model could be used for studying neuroprotective treatments for retarding or halting the progressive nigrostriatal degeneration caused by free radicals in the iron-rich basal ganglia.

Dopaminergic and peptidergic mRNA levels in juvenile rat brain after prenatal cocaine treatment

The effects of prenatal cocaine treatment on gene expression in dopaminergic pathways of juvenile rats were investigated by in situ hybridization histochemistry. Pregnant rats from gestational day 8 to 20 were administered one of the following treatments: (A) 40 mg/kg cocaine hydrochloride/3 ml/day s.c.; (B) 0.9% saline/3 ml/day s.c. and pair fed to cocaine-exposed dams; (C) 0.9% saline/3 ml/day s.c. and placement on cellulose-diluted diet to match the caloric intake of the cocaine-treated group without explicit food restriction; (D) no injection and lab chow diet. Levels of mRNA for the dopamine transporter, tyrosine hydroxylase, cholecystokinin, D1 and D2 dopamine receptors and enkephalin were quantitated in relevant dopaminergic regions of forebrain and midbrain of offspring that were sacrificed on postnatal day 21. Quantitative analysis revealed no significant changes in mRNA levels in any of the brain regions examined. In the present animal model, cocaine exposure in utero had no significant effect on mRNA levels of the dopamine transporter, D1 or D2 dopamine receptors, enkephalin, tyrosine hydroxylase, or cholecystokinin in juvenile rats.

Dopaminergic regulation of epileptic activity

We evaluated the role of dopamine systems in the propagation of epileptic Focal, limbic seizures were produced by systemically administered pilocarpine (200 mg/kg, i.p.); as previously described this dose produces limbic stereotypes but neither convulsions nor seizure-related brain damage. The systemic pretreatment with D-1, but not D-2, agonists induced convulsions identical to those produced by a higher, convulsant dose of pilocarpine (400 mg/kg). Conversely, the pretreatment with D-1 receptor antagonists prevented the convulsions whereas the D-2 antagonists facilitated the pilocarpine-induced seizures. Furthermore, we studied the effects of intracerebral injections of dopamine agents on seizures induced by pilocarpine. Nigral microinjection of D-1 agonists strongly induced motor seizures in rats treated with the low dose of pilocarpine. On the other hand, microinjection of D-1 antagonists prevented the motor seizures induced by the high dose of pilocarpine. This study indicates that the two dopamine receptor subtypes, D-1 and D-2, exert opposing roles in the control of epilepsy propagation. Substantia nigra pars reticulata appears to be primarily involved in the dopamine-mediated modulation of seizures.

Plasma HVA, tardive dyskinesia and psychotic symptoms in long-term drug-free inpatients with schizophrenia

Plasma homovanillic acid (pHVA) levels were measured in 16 chronically ill patients with schizophrenia who also suffered from tardive dyskinesia, and in a group of 14 chronically ill patients with schizophrenia who did not have tardive dyskinesia. All patients were studied following an extensive drug-free period (mean = 32.9 months). Patients with orofacial dyskinesia had significantly lower levels of pHVA than did controls. In patients without tardive dyskinesia, pHVA levels were significantly correlated with both positive and negative symptomatology. In contrast, pHVA levels from patients with tardive dyskinesia bore neither a significant nor a nearly significant relationship to symptomatology. The implications of these findings for dopaminergic models of tardive dyskinesia are discussed.