Decrease in caudate glutamatergic concentrations in pediatric obsessive-compulsive disorder patients taking paroxetine

OBJECTIVE: To measure in vivo neurochemical changes in the caudate nucleus in pediatric obsessive-compulsive disorder (OCD) before and after treatment. METHOD: Single-voxel proton magnetic resonance spectroscopic (1H-MRS) examinations of the left caudate were conducted in 11 psychotropic drug-naive children, aged 8 to 17 years, with OCD before and after 12 weeks of monotherapy with the selective serotonin reuptake inhibitor paroxetine (10-60 mg/day) and 11 healthy children aged 8 to 17 years. A different sample of 8 pediatric OCD patients and 8 healthy children had a 1H-MRS examination of occipital cortex. RESULTS: Caudate glutamatergic concentrations (Glx) were significantly greater in treatment-naive OCD patients than in controls but declined significantly after paroxetine treatment to levels comparable with those of controls. Decrease in caudate Glx was associated with decrease in OCD symptom severity. Occipital Glx did not differ between OCD patients and controls. CONCLUSIONS: These preliminary findings provide new evidence of Glx abnormalities in the caudate nucleus in pediatric OCD and suggest that paroxetine treatment may be mediated by a serotonergically modulated reduction in caudate Glx.     

Neurochemical analyses in pediatric obsessive-compulsive disorder in patients treated with cognitive-behavioral therapy

OBJECTIVE: To investigate neurochemical changes in the caudate nucleus of pediatric obsessive-compulsive disorder (OCD) patients before and after cognitive-behavioral therapy (CBT), and to examine corresponding changes in symptom severity. METHOD: Single-voxel proton magnetic resonance spectroscopic (1H-MRS) examination of the left caudate was conducted in 21 treatment-na?ve children, aged 6 to 16 years, before and after 12 weeks of CBT. Subjects were measured at baseline and posttreatment by the Yale-Brown Obsessive Compulsive Scale for Children, Hamilton Depression Rating Scale, and Hamilton Anxiety Rating Scale. RESULTS: No significant changes in caudate neurochemistry were observed in OCD patients before and after CBT despite unambiguous improvement in OCD symptoms, depression, and anxiety. CONCLUSIONS: Findings suggest that reduction in caudate Glx may be specific to SSRI treatment and not due to a more generalized treatment response or spontaneous improvement of symptoms. Differential sets of pathophysiologic and treatment response markers may moderate/mediate the effects of particular treatments on outcome.     

Cerebral blood volume and clinical changes on the third day of placebo substitution for SSRI treatment.

BACKGROUND: Interruptions in SSRI treatment have been associated with adverse effects that can resemble depressive illness. We hypothesized that brain regions implicated in depression, with extensive serotonergic innervation, would exhibit changes in activity associated with emergence of symptoms following drug discontinuation. METHODS: Subjects meeting DSM-IV criteria for remitted major depression on 20 mg/day of either fluoxetine or paroxetine were recruited into this 6-week study. During weeks 2 and 6, subjects underwent a 3-day period in which either active drug or placebo was substituted for their medication under double-blind conditions. Cerebral blood volume (CBV) maps were obtained via dynamic susceptibility magnetic resonance imaging at the end of each double-blind period. RESULTS: In the paroxetine group, change in CBV in left medial superior frontal region and left caudate nucleus correlated significantly with change in Discontinuation Emergent Symptom Scale and Hamilton Depression Rating Scale (HDRS; R2 = 0.66, p =.0007; R2 = 0.51, p =.006; and R2 = 0.43, p =.015; R2 = 0.32, p =.043, respectively). CONCLUSIONS: These data demonstrate that changes in regional CBV of left prefrontal cortex and left caudate nucleus correlate with the emergence of discontinuation symptoms and increased HDRS after interruption of paroxetine treatment.     

Differential cerebral metabolic changes with paroxetine treatment of obsessive-compulsive disorder vs major depression

BACKGROUND: Serotonin reuptake inhibitors (SRIs) effectively treat both major depressive disorder (MDD) and obsessive-compulsive disorder (OCD). We compared and contrasted the functional neuroanatomical effects of SRIs in OCD and MDD as these 2 disorders occurred separately and concurrently by measuring pretreatment to posttreatment cerebral glucose metabolic changes in OCD vs MDD vs concurrent OCD + MDD. METHODS: We obtained [(18)F]fluorodeoxyglucose positron emission tomography (PET) brain scans on 25 subjects with OCD, 25 with MDD, and 16 with concurrent OCD + MDD before and after 8 to 12 weeks of treatment with paroxetine hydrochloride. Controls (n = 16) were scanned 10 to 12 weeks apart without treatment. Treatment response was defined as a more than 25% decline in OCD symptom severity, a more than 50% decline in MDD severity, and "much improved" clinical global impression. RESULTS: Although all patient groups received the same paroxetine dose for the same duration, regional metabolic changes differed significantly among diagnostic groups. Subjects with OCD alone showed significant metabolic decreases in the right caudate nucleus, right ventrolateral prefrontal cortex (VLPFC), bilateral orbitofrontal cortex, and thalamus that were not seen in any other group. Both the MDD and concurrent OCD + MDD groups showed metabolic decreases in the left VLPFC and increases in the right striatum. Treatment response was associated with a decrease in striatal metabolism in nondepressed OCD patients but with an increase in striatal activity in patients with OCD + MDD. CONCLUSIONS: Brain metabolic responses to SRIs are both disorder-specific and response-specific. They vary according to the underlying pathophysiology of the patient and the degree of symptomatic improvement.     

Differential brain metabolic predictors of response to paroxetine in obsessive-compulsive disorder versus major depression

OBJECTIVE: Serotonin reuptake inhibitor (SRI) medications are effective in the treatment of both major depressive disorder and obsessive-compulsive disorder (OCD), but it is unknown whether the neural substrates of treatment response for the two disorders are the same or different. The authors sought to identify pretreatment cerebral glucose metabolic markers of responsiveness to SRI treatment in patients with OCD versus major depressive disorder and to determine whether the pretreatment patterns associated with improvement of OCD symptoms were the same as or different from those associated with improvement of major depressive disorder symptoms. METHOD: [(18)F]Fluorodeoxyglucose positron emission tomography was used to measure cerebral glucose metabolism in 27 patients with OCD alone, 27 with major depressive disorder alone, and 17 with concurrent OCD and major depressive disorder, who were all then treated with 30-60 mg/day of paroxetine for 8-12 weeks. Correlations were calculated between pretreatment regional metabolism and pre- to posttreatment changes in the severity of OCD symptoms, depressive symptoms, and overall functioning. RESULTS: While improvement of OCD symptoms was significantly correlated with higher pretreatment glucose metabolism in the right caudate nucleus (partial r=-0.53), improvement of major depressive disorder symptoms was significantly correlated with lower pretreatment metabolism in the amygdala (partial r=0.71) and thalamus (partial r=0.34) and with higher pretreatment metabolism in the medial prefrontal cortex and rostral anterior cingulate gyrus (Talairach coordinates: x=0, y=62, z=10) (z=2.91). CONCLUSIONS: These findings suggest that, although both OCD and major depressive disorder respond to SRIs, the two syndromes have different neurobiological substrates for response. Elevated activity in the right caudate may be a marker of responsiveness to antiobsessional treatment, while lower right amygdala activity and higher midline prefrontal activity may be required for response of depressive symptoms to treatment.     

Paroxetine treatment of compulsive hoarding

OBJECTIVE: Compulsive hoarding, found in many patients with obsessive-compulsive disorder (OCD), has been associated with poor response to serotonin reuptake inhibitor (SRI) medications in some reports. However, no prior study has quantitatively measured response to standardized pharmacotherapy in compulsive hoarders. We sought to determine whether compulsive hoarders would respond as well as non-hoarding OCD patients to the SRI, paroxetine. METHODS: Seventy-nine patients with OCD (32 patients with the compulsive hoarding syndrome and 47 patients without prominent hoarding symptoms) were treated openly with paroxetine (mean dose 41.6+/-12.8 mg/day; mean duration 80.4+/-23.5 days) according to a standardized protocol, from 3/1993 to 7/2005. All subjects were free of psychotropic medication for at least four weeks prior to study entry. No psychotherapy or psychotropic medications except paroxetine were allowed during the study period. Subjects were assessed before and after treatment with the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Hamilton Depression Rating Scale (HDRS), Hamilton Anxiety Scale (Ham-A), Global Assessment Scale (GAS), and Clinical Global Impression/Improvement (CGI) scale. RESULTS: Both compulsive hoarders and non-hoarding OCD patients improved significantly with treatment (p<0.001), with nearly identical changes in Y-BOCS, HDRS, Ham-A, and GAS scores. There were no significant differences between groups in the proportions of patients who completed or responded to treatment. Hoarding symptoms improved as much as other OCD symptoms. CONCLUSIONS: Compulsive hoarders responded as well to paroxetine treatment as non-hoarding OCD patients, suggesting that SRI medications are effective for compulsive hoarding. Controlled trials of SRI medications for compulsive hoarding are now warranted.     

Case of prolonged recovery from serotonin syndrome caused by paroxetine]

We report a case of serotonin syndrome in a patient being treated with paroxetine for depression. Despite prompt discontinuation of medication, his serotonin syndrome continued for 10 days before full consciousness was restored. The patient was a 48-year-old male with chief complaints of hypobulia and suicidal thoughts. He consulted as a psychiatric outpatient, and oral paroxetine 20 mg/day, etizolam 1.0 mg/day, and brotizolam 0.25 mg/day were immediately started. Upsurge of feeling and disinhibition state were noted the following day, then on treatment day 6 his condition deteriorated to substupor state and he was admitted for further treatment. On admission, change of mental condition (consciousness disturbance), perspiration, hyperreflexia, myoclonus and tremor were seen, and serotonin syndrome caused by paroxetine was suspected. Paroxetine was thus discontinued, and under intravenous drip his condition gradually improved. However, it was not until the 10th hospital day that he became fully alert. In examinations, no infectious, metabolic or organic diseases were detected. The patient's condition often improves with in 24 hours of discontinuation of the causative medication in serotonin syndrome. Symptoms continued for 10 days in this patient, however, perhaps because paroxetine was administered for 6 days before discontinuation. In addition, interaction with other medications may have occurred. Therefore, when serotonin syndrome is suspected, prompt discontinuation of the suspected causative medication, followed by close monitoring of the pharmacokinetics is warranted.     

Paroxetine open-label treatment of pediatric outpatients with obsessive-compulsive disorder.

OBJECTIVE: Paroxetine is a selective serotonin reuptake inhibitor with demonstrated efficacy in treating obsessive-compulsive disorder (OCD) in adults. This study evaluates the safety and effectiveness of paroxetine in pediatric OCD patients. METHOD: In a 12-week, open-label trial of paroxetine, 20 OCD outpatients, aged 8 to 17 years, were treated for OCD with daily doses ranging from 10 to 60 mg. Target symptoms were rated at regular intervals with the Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS), the Children's Global Assessment Scale, the Clinical Global Impression Scale, the Hamilton Anxiety Rating Scale, and the Yale Global Tic Severity Scale. RESULTS: Paroxetine proved relatively safe in this brief trial with a small sample and appeared to be effective in patients with OCD; mean CY-BOCS scores decreased significantly (z = 3.49, p = .0005) from 30.6 +/- 3.5 to 21.6 +/- 6.8 on medication. The most common side effects (n > or = 2) were hyperactivity/behavioral activation, headache, insomnia, nausea, and anxiety. Paroxetine did not have to be discontinued in any of the patients because of side effects; the most serious side effects included hyperactivity/behavioral activation in 3 younger patients (< 10 years) necessitating dosage reduction but not discontinuation. CONCLUSIONS: Preliminary evidence suggests that short-term treatment of pediatric OCD outpatients with paroxetine may be relatively safe and effective.     

Decreased caudate N-acetyl-l-aspartic acid in pediatric obsessive-compulsive disorder and the effects of behavior therapy

The current study used magnetic resonance spectroscopy (MRS) to investigate differences in absolute levels of neurochemicals in the head of the caudate nucleus (HOC) and anterior cingulate cortex (ACC) between 15 children with obsessive-compulsive disorder (OCD) and a matched control group, as well as the effects of behavior therapy on these chemicals. At baseline, absolute levels of N-acetyl-l-aspartate (NAA) in the left HOC were significantly lower in non-medicated patients (N=8) with OCD compared to medicated patients (N=5) and compared to matched controls (N=9). Exploratory analyses provided preliminary data suggesting that behavior therapy is associated with a decrease in Glx (glutamate+glutamine) in the right HOC (N=7). The baseline differences in NAA replicate previous finding from the adult literature and show a relationship between NAA in OCD across the lifespan. The changes in Glx raise the possibility that behavior therapy and medication treat OCD symptoms through similar pathways.     

Successful treatment of seasonal compulsive syndrome with phototherapy]

We report the case of a 40-year-old woman with a seasonal form of obsessive compulsive disorder (OCD) which was usually accompanied by obsessions and occurred only in autumn or winter. Frequently, the OCD symptomatology was accompanied by depression. After a 12-day treatment with full spectrum bright light (3000 lux; 2 hours a day between 9 and 11 am) without changing the long-term antidepressive medication (125 mg amitriptyline/day) there was a complete remission of OCD symptomatology, with no relapse during the next months.     

Acute and long-term treatment and prevention of relapse of obsessive-compulsive disorder with paroxetine

BACKGROUND: Limited information is available regarding optimal dosing or long-term pharmacotherapy with serotonin reuptake inhibitors in obsessive-compulsive disorder. This study evaluated the acute safety and efficacy and long-term efficacy, safety, and impact on relapse prevention of paroxetine in obsessive-compulsive disorder. METHOD: We enrolled 348 outpatients with DSM-III-R obsessive-compulsive disorder in phase 1, a 12-week randomized, double-blind, parallel study of fixed doses of paroxetine (20 mg/day, 40 mg/day, or 60 mg/day) and placebo. In phase 2, 263 phase 1 completers were enrolled in 6 months of flexibly dosed open-label paroxetine treatment. In phase 3, 105 responders to open-label paroxetine were randomized to 6-month double-blind, fixed-dose, parallel paroxetine/placebo treatment to evaluate long-term efficacy, safety, and impact on relapse prevention. The study was conducted from July 1991 to February 1994. RESULTS: Patients in phase 1 acute treatment receiving 40 mg/day or 60 mg/day of paroxetine improved significantly (p < .05) more than those receiving placebo; the mean reduction in Yale-Brown Obsessive-Compulsive Scale score was 25% on 40 mg/day of paroxetine and 29% on 60 mg/day compared with 13% on placebo. During phase 3, long-term treatment, a greater proportion of placebo- (59%) than paroxetine-treated (38%) patients relapsed. Paroxetine was well tolerated at all doses, with no significant increase in frequency of adverse events during long-term compared with short-term therapy. Greater adverse events in the placebo than in the paroxetine group in phase 3 probably represent a discontinuation effect. CONCLUSION: Paroxetine doses of 40 mg/day and 60 mg/day (but not 20 mg/day) are effective in treating acute obsessive-compulsive disorder. Long-term treatment with paroxetine is effective and safe, decreases the rate of relapse, and lengthens the time to relapse.     

Hallucination induced by paroxetine discontinuation in patients with major depressive disorders

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

Caudate volume differences among treatment responders,non-responders and controls in children with obsessive–compulsive disorder

Treatment response in obsessive–compulsive disorder (OCD) is heterogeneous and the neurobiological underpinnings of such variability are unknown. To investigate this issue, we looked for differences in brain structures possibly associated with treatment response in children with OCD. 29 children with OCD (7–17 years) and 28 age-matched controls underwent structural magnetic resonance imaging. Patients then received treatment with fluoxetine or group cognitive-behavioral therapy during 14 weeks, and were classified as treatment responders or non-responders. The caudate nucleus, thalamus and orbitofrontal cortex were selected a priori, according to previous evidence of their association with OCD and its treatment. Gray matter (GM) volume comparisons between responders, non-responders and controls were performed, controlling for total GM volume. 17 patients were classified as responders. Differences among responders, non-responders and controls were found in both caudate nuclei (both p-values = 0.041), but after Bonferroni correction for multiple comparisons, these findings were non-significant. However, after excluding the effect of an outlier, findings were significant for the right caudate (p = 0.004). Pairwise comparisons showed larger caudate GM volume in responders versus non-responders and controls, bilaterally. The right caudate accounted for 20.2% of the variance in Y-BOCS changes after treatment in a linear regression model, with a positive correlation (p = 0.016). We present a possible neural substrate for treatment response in pediatric OCD, which is in line with previous evidence regarding the caudate nucleus. Considering the limitations, further research is needed to replicate this finding and elucidate the heterogeneity of treatment response in children with OCD (National Clinical Trials Registration Number: NCT01148316).

     

Diffusion-weighted imaging in Sydenham’s chorea

Purpose

The purpose of this study was to determine of caudate nucleus changes in diffusion-weighted magnetic resonance imaging.

Methods

A total of 13 children (four males and nine females) with history of Sydenham’s chorea and 13 healthy controls were included in to the study. Diffusion cranial magnetic resonance imaging was performed in all subjects before prednisone treatment. Prednisone (2 mg/kg/day, maximum dose 60 mg/day) was used during 4 weeks and then progressively discontinued (20 % of the initial dose was reduced at each 5 days). Two months later, magnetic resonance imaging was repeated.

Results

Before and after 8 weeks of prednisone treatment, apparent diffusion coefficients (ADCs) were calculated for right and left caudate nucleus. The ADC values were significantly different before treatment and 2 months after imaging. For the left caudate nucleus, ADC values before treatment (0.69?±?0.038) were significantly lower than after treatment (0.95?±?0.04). For the right caudate nucleus, ADC values before treatment (0.72?±?0.06?×?10^?3) were significantly lower than after treatment (0.93?±?0.04?×?10^?3).

Conclusions

Although cranial and caudate nucleus magnetic resonance imaging findings were normal, the low ADC value findings in our study support the autoimmune inflammation in basal ganglia of Sydenham’s chorea.     

Venlafaxine versus clomipramine in the treatment of obsessive-compulsive disorder: a preliminary single-blind, 12-week,controlled study

BACKGROUND: The objective of this study was to investigate, in a single-blind manner over a period of 12 weeks, the efficacy and tolerability of venlafaxine versus clomipramine in the treatment of obsessive-compulsive disorder (OCD). METHOD: Patients with a DSM-IV diagnosis of OCD and a Yale-Brown Obsessive Compulsive Scale (YBOCS) score >/= 16 were randomly assigned to receive venlafaxine, 225 to 350 mg/day (26 patients), or clomipramine, 150 to 225 mg/day (47 patients), for 12 weeks, with dosage adjustments according to tolerability and response to treatment. All patients were medication-free from at least 2 months prior to study enrollment. Efficacy measures were the YBOCS and the Clinical Global Impressions scale (CGI), which were completed at baseline and every 4 weeks.We defined responders as patients who had an improvement from baseline in YBOCS score of >/= 35% and a CGI score 相似文献   

Decrease in thalamic volumes of pediatric patients with obsessive-compulsive disorder who are taking paroxetine

BACKGROUND: Thalamic dysfunction has been implicated in obsessive-compulsive disorder (OCD). While OCD frequently has its onset during childhood, to our knowledge, no prior study has measured neuroanatomical changes in the thalamus of patients with OCD near the onset of illness, and before and after treatment. METHODS: Volumetric magnetic resonance imaging studies were conducted in 21 psychotropic drug-naive children, aged 8 to 17 years, with OCD and 21 case-matched healthy comparison subjects. Magnetic resonance imaging studies were also conducted in 10 of the 21 patients with OCD after 12 weeks of monotherapy with the selective serotonin reuptake inhibitor, paroxetine hydrochloride. RESULTS: Thalamic volumes were significantly greater in treatment-naive patients with OCD than in controls but declined significantly after paroxetine monotherapy to levels comparable with those of controls. Decrease in thalamic volume in patients with OCD was associated with reduction in OCD symptom severity. CONCLUSIONS: Our findings provide new evidence of thalamic abnormalities in pediatric OCD and further suggest that paroxetine treatment may be paralleled by a reduction in thalamic volume. These reductions may, however, not be specific to paroxetine treatment and could be due to a more general treatment response, and/or spontaneous improvement in symptoms. Our findings are preliminary given the small sample size and our inability to measure discrete thalamic nuclei.     

A 1H magnetic resonance spectroscopy study in adults with obsessive compulsive disorder: relationship between metabolite concentrations and symptom severity

1H magnetic resonance spectroscopy (1H MRS) studies exploring brain metabolites, especially glutamine + glutamate (Glx), in obsessive compulsive disorder (OCD) are of vital interest for trying to understand more about the pathophysiology of OCD. Therefore, we conducted the present 1H MRS study with the aims of (1) comparing MRS metabolites in a group of adult patients with OCD and a group of healthy controls, and (2) examining the relationship between MRS metabolite concentrations and symptom severity in the patient group. Three brain regions were studied, the right caudate nucleus, the anterior gyrus cinguli and the occipital cortex bilaterally. Since multivariate analysis is a highly useful tool for extraction of 1H MRS data, we applied principal component analysis (PCA) and partial least square projection to latent structures (PLS) to the MRS data. PLS disclosed a strong relationship between several of the metabolites and OCD symptom severity, as measured with Yale-Brown obsessive-compulsive scale (YBOCS): the YBOCS score was found to be positively correlated to caudate creatine, Glx, glutamate, and choline compounds as well as occipital cortex myoinositol, and negatively correlated to occipital cortex Glx. The negative correlation between occipital cortex Glx and YBOCS was the most impressive. PCA did not reveal any tendency for a separation between the patients with OCD and controls with respect to MRS metabolites. The results are discussed in relation to corticostriatothalamocortical feedback and previous observations of poor visuospatial ability in OCD.     

Association study of polymorphisms in the excitatory amino acid transporter 2 gene (SLC1A2) with schizophrenia

Background

This naturalistic open label follow-up study had three objectives: 1) To observe the course of illness in Panic Disorder patients receiving long-term versus intermediate-term paroxetine treatment 2) To compare the relapse rates and side-effect profile after long-term paroxetine treatment between patients with Panic Disorder and Panic Disorder with Agoraphobia. 3) To observe paroxetine's tolerability over a 24 month period.

Methods

143 patients with panic disorder (PD), with or without agoraphobia, successfully finished a short-term (ie 12 week) trial of paroxetine treatment. All patients then continued to receive paroxetine maintenance therapy for a total of 12 months. At the end of this period, 72 of the patients chose to discontinue paroxetine pharmacotherapy and agreed to be monitored throughout a one year discontinuation follow-up phase. The remaining 71 patients continued on paroxetine for an additional 12 months and then were monitored, as in the first group, for another year while medication-free. The primary limitation of our study is that the subgroups of patients receiving 12 versus 24 months of maintenance paroxetine therapy were selected according to individual patient preference and therefore were not assigned in a randomized manner.

Results

Only 21 of 143 patients (14%) relapsed during the one year medication discontinuation follow-up phase. There were no significant differences in relapse rates between the patients who received intermediate-term (up to 12 months) paroxetine and those who chose the long-term course (24 month paroxetine treatment). 43 patients (30.1%) reported sexual dysfunction. The patients exhibited an average weight gain of 5.06 kg. All patients who eventually relapsed demonstrated significantly greater weight increase (7.3 kg) during the treatment phase.

Conclusions

The extension of paroxetine maintenance treatment from 12 to 24 months did not seem to further decrease the risk of relapse after medication discontinuation. Twenty-four month paroxetine treatment is accompanied by sexual side effects and weight gain similar to those observed in twelve month treatment.     

A double-blind switch study of paroxetine and venlafaxine in obsessive-compulsive disorder

BACKGROUND: The treatment guidelines for obsessive-compulsive disorder (OCD) propose to switch serotonin reuptake inhibitors (SRIs) in case of refractoriness. However, no controlled research has been published yet that prospectively examined the effects of changing SRIs. This article describes the first double-blind switch study of 2 SRIs in patients with OCD. METHOD: 150 patients with primary OCD, according to DSM-IV criteria, were randomly assigned in a 12-week, double-blind trial to receive dosages titrated upward to 300 mg/day of venlafaxine (N = 75) or 60 mg/day of paroxetine (N = 75). Primary efficacy was assessed by the change from baseline on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), and nonresponse was defined as less than 25% reduction on the Y-BOCS. After a 4-week tapering phase, 43 nonresponders were switched to 12 additional weeks of the alternate antidepressant, of which 16 patients received venlafaxine and 27 received paroxetine. RESULTS: Eighteen of 43 patients benefited from a switch to the alternate SRI with a mean +/- SD decrease of at least 25% on the Y-BOCS. At the end of 12 weeks, responder rates were 56% for paroxetine (15/27) and 19% for venlafaxine (3/16). An intent-to-treat, last-observation-carried-forward analysis demonstrated a mean decrease on the Y-BOCS of 1.8 +/- 3.5 in the venlafaxine group and 6.5 +/- 7.1 in the paroxetine group. After 2 consecutive SRI trials, 109 of 150 patients (73%) achieved a Y-BOCS decrease of at least 25%. CONCLUSION: The results of the current study show that 42% of the nonresponders benefited from a crossover to the other SRI, and that paroxetine was more efficacious than venlafaxine in the treatment of nonresponders to a previous SRI trial. Switching SRIs in case of refractoriness may be considered a useful strategy for patients with OCD.     

Decreased thalamic blood flow in obsessive-compulsive disorder patients responding to fluvoxamine

Functional imaging studies have pointed to a role of the orbitofrontal cortex (OFC), striatum and thalamus in the pathophysiology of obsessive-compulsive disorder (OCD). Effective treatment has been found to change brain activity within this circuitry. The aim of the present study was to explore possible differential effects of OCD responders and non-responders to drug treatment on the regional cerebral blood flow (rCBF). Measurements of rCBF were carried out in 15 out of 22 patients with OCD who completed an open-label trial with fluvoxamine. Patients were studied with 99mTc-HMPAO single photon emission computed tomography (SPECT) before and after 12 weeks of treatment. In addition, structural magnetic resonance imaging was obtained on all patients. Regions of interest comprised the OFC, caudate nucleus, putamen and thalamus. Seven patients responded to treatment. Levels of rCBF decreased significantly in the left caudate nucleus and the left and right putamen in both responders and non-responders to treatment. In responders, but not in non-responders, a significant decrease in rCBF was found in the right thalamus. Pre-treatment cerebellar and whole brain HMPAO uptake was significantly higher in responders to treatment compared with non-responders. We suggest that the thalamus plays a central role in the response to drug treatment.