Sylvain Grignon

Cognitive effects of antipsychotic dosage and polypharmacy: a study with the BACS in patients with schizophrenia and schizoaffective disorder.

Antipsychotic polypharmacy and high doses have been associated with poorer outcome, longer hospital stays, and increased side effects. The present naturalistic study assessed the cognitive effects of antipsychotics in 56 patients with a diagnosis of schizophrenia or schizoaffective disorder, using the Brief Assessment of Cognition in Schizophrenia (BACS). Antipsychotic daily dose (ADD) was expressed as mg risperidone equivalents/day (RIS eq), using a model based on drug doses from the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) study for second generation antipsychotics (SGA) and chlorpromazine equivalents for first generation antipsychotics (FGA), with a 1/1 equivalence between haloperidol and risperidone. Increasing age was associated with polypharmacy, FGA prescription and decreasing BACS score. FGA prescription, in turn, predicted a poorer cognitive functioning, independently of age, PANSS subscores and ADD. ADD was associated with decreasing cognitive scores, an effect that remained significant after controlling for age, PANSS or polypharmacy. The detrimental cognitive effects of polypharmacy, in turn, appeared to be mediated by ADD. Different methods of data fitting suggested that ADD above 5—6 mg RIS eq/day were associated with lower BACS scores. Overall, these results show that increasing antipsychotic daily dose is associated with poorer cognitive functioning at doses lower than previously thought, independently of the number of antipsychotic drugs.

Human evidence of a supra‐spinal modulating role of dopamine on pain perception

Over the last decades, remarkable progresses have been accomplished regarding the understanding of the neurophysiologic and neuropharmacological bases of pain. A growing preclinical literature supports a role for substance P, endogenous opioids, glutamate, serotonin, and norepinephrine in pain perception. Recently, a series of studies explored the function of dopamine in pain perception, which we review here, while focusing on human studies.

DRD3 Ser9Gly Polymorphism Is Related to Thermal Pain Perception and Modulation in Chronic Widespread Pain Patients and Healthy Controls

UNLABELLED Experimental studies showed that dopamine influences pain perception in healthy volunteers. Dopamine dysfunctions have been linked to the physiopathology of fibromyalgia (FM), which is associated with hyperalgesia and deficient pain inhibition. We sought to investigate the relationships between catecholamine-related polymorphisms [dopamine-D(3) receptor (DRD3) Ser9Gly and catechol-O-methyltransferase (COMT) Val158Met] and thermal pain measures in healthy subjects and FM patients. Seventy-three subjects (37 FM patients and 36 controls) participated in this study. Thermal pain thresholds (TPTs) were measured using a Peltier thermode. Inhibitory systems were elicited using a thermal tonic pain stimulation administered before and after activation of the diffuse noxious inhibitory controls (DNIC) by means of a cold-pressor test. Genetic analyses were performed using polymerase chain reaction. Regression analyses were performed across and within groups. FM was associated with lower TPTs and deficient pain inhibition. DRD3 Ser9Gly polymorphism predicted (1) DNIC efficacy across groups and (2) thermal TPTs in FM patients. COMT Val158Met and thermal pain measures were not related. These preliminary results suggest that the DRD3 Ser9Gly polymorphism influences DNIC efficacy and TPTs and that this latter relationship is present only in FM patients. Two core psychophysical features of FM appear to be significantly influenced by limbic dopamine functioning. PERSPECTIVE This experimental study is the first to relate DNIC and TPTs to a functional polymorphism of limbic dopamine-D3 receptors. As lowered pain thresholds and deficient pain inhibition are 2 core features of fibromyalgia, these preliminary results may help identify a subgroup of FM patients who require closer medical attention.

No relationship between the ins del polymorphism of the serotonin transporter promoter and pain perception in fibromyalgia patients and healthy controls

Background: In animals, decades of research have shown that serotonin (5‐HT) is involved in endogenous pain inhibition systems, which are deficient in chronic pain disorders such as fibromyalgia (FM). In humans, there is preliminary evidence showing that 5‐HT is involved in the FM pathophysiology. In the current endophenotyping study, we sought to investigate, for the first time in humans, the relationships between the serotonin transporter promoter region (5‐HTTLPR) polymorphism and experimentally‐induced pain perception/inhibition in healthy controls (HC) and FM patients.

Assessment of malondialdehyde levels in schizophrenia: A meta-analysis and some methodological considerations ☆

Oxidative stress has long been suggested to participate in the pathophysiology of schizophrenia. Most of the published data on the subject rely on malondialdehyde levels assessment through thiobarbituric acid reactive substances (TBARS), despite significant methodological concerns. The present paper reports on a meta-analysis of studies published up to July 2006. Relevant studies were identified through PubMed search and the References section of experimental and review papers on the subject. Studies were retained for analysis if they provided adequate methods description, controls and subjects numbers, means and standard deviations. Using a random effect model, an effect size of 1.22 (CI: 0.64-1.80) was found, with significant bias and high heterogeneity. Inspection of the bias assessment plot suggested a lower value in the order of d approximately 0.5, in line with the results of the larger studies. The heterogeneity of the results appeared to be unrelated to assay type or biological sample. However a meta-regression analysis suggested an association, at trend level, between the precision-weighted effect size and the proportion of drug-free patients, which might therefore account for some of the heterogeneity.

Combination of prenatal immune challenge and restraint stress affects prepulse inhibition and dopaminergic/GABAergic markers

Gestational immune challenge with the viral-like antigen poly I:C is a well-established neurodevelopmental model of schizophrenia. However, exposure to inflammation during early life may sensitize the developing brain to secondary insults and enhance the central nervous system vulnerability. To gain a better understanding of the pathophysiology of schizophrenia, we thus developed a two-hit animal model based on prenatal poly I:C immune challenge followed by restraint stress in juvenile mice. C57BL/6 gestational mice were intraperitoneally injected with poly I:C or saline at gestational day 12. Pups were then submitted or not, to restraint stress for 2h, for three consecutive days, from postnatal days 33 to 35. Prepulse inhibition (PPI) of acoustic startle response is commonly used to assess sensorimotor gating, a neural process severely disrupted in patients with schizophrenia. Our results revealed that the combination of prenatal immune challenge with poly I:C followed by a restraint stress period was able to induce a PPI disruption in 36-day-old pups, as opposed to each insult applied separately. PPI deficits were accompanied by dopaminergic and GABAergic abnormalities in the prefrontal cortex and striatum. Indeed, measurements of cortical and striatal dopamine D2 receptor (D2R) mRNA and protein levels revealed that the combination of gestational exposure to poly I:C and postnatal restraint stress induced an increase in D2R protein and mRNA levels. Likewise, the combination of both insults reduced the mRNA and protein expression levels of the 67 kDa form of glutamic acid decarboxylase (GAD67), in those two brain regions. To our knowledge, this two-hit animal model is the first in vivo model reporting PPI deficits at pubertal age. This two-hit animal model may also help in studying innovative therapies dedicated to the treatment of schizophrenia, especially in its early phase.

Pain Perception in Schizophrenia: Evidence of a Specific Pain Response Profile

OBJECTIVE Ever since the characterization of schizophrenia, clinicians have noted abnormal pain sensitivity in their patients. The published literature, however, is inconsistent concerning the nature of the change reported. The objective of this study was to characterize the pain response profile of schizophrenic patients by providing both acute and prolonged (i.e., rapidly repeating) painful stimuli to schizophrenic participants and control subjects. PARTICIPANTS Twelve schizophrenic subjects and eleven controls were included in the final analysis. Diagnosis was made according to Diagnostic and Statistical Manual of mental disorders-4th edition, text revision (DSM-IV-TR) criteria. METHODS Intermittent, transcutaneous stimulations of the left sural nerve were administered to all participants. Painful sural nerve stimulations provoked a nociceptive flexion reflex response which was measured using an electromyographic recording of the bicep femoris muscle. Pain ratings were obtained using a 0-10 verbal numerical scale. Among schizophrenic participants, the relationship between subjective pain, reflex amplitude, and clinical features was investigated. The Positive and Negative Syndrome Scale, Calgary Depression Scale for Schizophrenia, and Subjective Scale to Investigate Cognition in Schizophrenia were used to evaluate clinical features. RESULTS Compared with controls, schizophrenic subjects showed increased sensitivity to acute pain (i.e., lower pain thresholds; P = 0.019), but decreased subjective pain sensitization (P = 0.027). Group differences in subjective pain sensitization were not accompanied by group differences in nociceptive reflex activity (P = 0.260), suggesting supraspinal origins to the change in pain experienced by schizophrenic subjects. Moreover, positive symptoms correlated negatively with pain threshold values among schizophrenic participants (r = -0.696, P = 0.012), suggesting that distortions of thought and function relate to pain sensitivity in schizophrenic patients. CONCLUSION Results indicate that schizophrenic subjects present a specific experimental pain response profile, characterized by elevated sensitivity to acute pain but reduced sensitivity to prolonged pain.

Tyrosine kinase inhibitors and cycloheximide inhibit Li+ protection of cerebellar granule neurons switched to non-depolarizing medium

Recently, it has been shown that Li+ robustly enhances the survival of cerebellar granule neurons acutely switched to non-depolarizing medium after maturing in vitro, a condition which elicits massive apoptotic death in this cell type. Tyrosine protein phosphorylation is known to underlie the activity of a number of trophic factors. This prompted us to investigate whether specific tyrosine kinase inhibitors could modulate the Li+ protection of cultured granule neurons switched to non-depolarizing medium. Genistein and herbimycin A dose dependently abolished the Li+ effect. Furthermore, this effect was substantially prevented by the translational inhibitor cycloheximide, suggesting that it requires de novo protein synthesis. Overall, these results suggest that Li+ protection of cerebellar granule neurons switched to non-depolarizing medium involves tyrosine kinases and transcriptional activation.

Comparative effectiveness and safety of antipsychotic drugs in schizophrenia treatment: a real-world observational study

The objective was to compare, in a real‐world setting, the risk of mental and physical health events associated with different antipsychotic drugs (clozapine, olanzapine, risperidone, quetiapine and first‐generation antipsychotics) in patients with SZ.

Antipsychotic-induced DRD2 upregulation and its prevention by α-lipoic acid in SH-SY5Y Neuroblastoma cells

Most antipsychotic (AP) drugs are dopamine (DA) D2 receptor (DRD2) antagonists and remain the main pharmacological treatment of schizophrenia. Long‐term AP use can give rise to tardive dyskinesia. It has been reported that chronic treatment with APs induces DRD2 upregulation and oxidative stress, which have been associated with tardive dyskinesia. We showed previously that H2O2‐induced oxidative stress increased DRD2 expression in human SH‐SY5Y neuroblastoma cells. We report here the effects of AP drugs on DRD2 expression levels in the same cell line and the effects of the inhibition of oxidative phenomena by (±)‐α‐lipoic acid treatment. Haloperidol, a first‐generation AP, induced an increase in DRD2 protein and mRNA levels, whereas amisulpride, a second‐generation AP, had no significant effect. (±)‐α‐Lipoic acid pretreatment reversed the haloperidol‐induced DRD2 upregulation in mRNA and protein levels. Furthermore, haloperidol induced a larger increase of oxidative stress biomarkers (protein carbonylation, lipid peroxidation, and superoxide anion production) than amisulpride. (±)‐α‐Lipoic acid also attenuated AP‐induced oxidative stress. Inhibition of catecholamine synthesis by α‐methyl‐DL‐tyrosine (AMPT) increased DRD2 expression and prevented further increase by APs. Our results suggest that haloperidol‐induced DRD2 upregulation is linked to oxidative stress and provide potential mechanisms by which (±)‐α‐lipoic acid can be considered as a therapeutic agent to prevent and treat side effects related to the use of first‐generation APs. Synapse, 2011.