Differential effects of olanzapine and risperidone on cognition in schizophrenia? A saccadic eye movement study

Recent studies suggest that novel antipsychotics have positive effects on certain cognitive functions in schizophrenia. The present study investigated this claim by means of saccadic paradigms, which provide a selective index of cognitive function. Thirty-three first-episode schizophrenic patients were randomly assigned to either olanzapine or risperidone treatment and compared with healthy control subjects for three saccadic paradigms. The influence of symptom profile, extrapyramidal symptoms, age, education, gender, hospitalization, and medication dose on cognitive performance was also investigated. Although the two patient groups did not differ from each other in task performance, both patient groups showed substantial problems in inhibitory control of saccades. A high level of education appeared to be protective for this impairment.

Interscan displacement-induced variance in PET activation data is excluded by a scan-specific attenuation correction

In PET activation studies, linear changes in regional cerebral blood flow may be caused by subject interscan displacements rather than by changes in cognitive state. The aim of this study was to investigate the impact of these artifacts and to assess whether they can be removed by applying a scan-specific calculated attenuation correction (CAC) instead of the default measured attenuation correction (MAC). Two independent data sets were analyzed, one with large (data I) and one with small (data II) interscan displacements. After attenuation correction (CAC or MAC), data were analyzed using SPM99. Interscan displacement parameters (IDP), obtained during scan realignment, were included as additional regressors in the General Linear Model and their impact was assessed by variance statistics revealing the affected brain volume. For data I, this volume reduced dramatically from 579 to 12 cm(3) (approximately 50-fold) at P(uncorr) </= 0.001 and from 100 to 0 cm(3) at P(corr) </= 0.05 when CAC was applied instead of MAC. Surprisingly, for data II, applying CAC instead of MAC still resulted in a substantial (approximately 10-fold) reduction of the affected volume from 23 to 2 cm(3) at P(uncorr) </= 0.001. We conclude that interscan displacement-induced variance can be prevented by applying a (realigned attenuation correction scan (e.g., CAC). With MAC data, introducing IDP covariates is not an alternative since they model only this variance. Even in data with minor interscan displacements, applying a (realigned attenuation correction method (e.g., CAC) is superior to a nonaligned MAC with IDP covariates.

Decision making performance in obsessive compulsive disorder

BACKGROUND

Neuro-imaging studies in OCD report the orbitofrontal cortex to be functionally abnormal. As these areas are presumed to be involved in decision making, studying this behavior in OCD may provide further insight into the cognitive deficits accompanying the disorder.

METHODS

Performance of 27 drug-free OCD patients and 26 healthy volunteers was compared on the decision making task of Bechara et al. [Cognition, 50 (1994) 7-15].

RESULTS

OCD patients and volunteers displayed comparable decision-making behavior. Within OCD patients, risk taking was independently related to both anxiety and OCD severity.

LIMITATIONS

Results must be regarded as preliminary, due to the limited number of OCD patients included and the lack of a clinical control group.

CONCLUSIONS

Although VMpfc function is not generally impaired, it seems to be involved in OCD; possibly in another way than could be measured with this task.

CLINICAL RELEVANCE

Clarification of cognitive distortions underlying OCD may guide development of new strategies for cognitive-behavioral therapy.

Evaluation of two cortical fraction estimation algorithms for the calculation of dynamic magnetic resonance renograms

With the high resolution of dynamic magnetic resonance imaging (MRI) scans it is possible to measure cortical renograms directly, but due to partial volume effects this is impossible for medullary renograms. With weighted subtraction of the cortical renogram from a mixed renogram it becomes possible to extract the medullary renogram. For this subtraction the fraction of cortical tissue, present in the region of interest in which the mixed renogram is determined, has to be calculated. We have evaluated two algorithms for calculation of the cortical fraction. Both algorithms use the fact that during an interval after the start of the cortical enhancement no medullary enhancement occurs. One algorithm calculates the ratio between the slopes of both enhancement curves. The other is based on minimising the medullary signal values using a least squares error (LSE) method. Using a computer model of the renograms and measurements on real patients we analysed the accuracy of both methods and determined the best parameters for each.

Heart rate variability as predictor of nonresponse to mirtazapine in panic disorder: a preliminary study

Using spectral analysis of heart rate, several studies have shown that panic disorder patients are characterized by a reduced heart rate variability (HRV), indicative of abnormalities in autonomous nervous system (ANS) function. We recently reported that patients with panic disorder, who did not respond to pharmacotherapy, were characterized at baseline by a higher heart rate. In this study, ANS functioning is investigated as a possible predictor of nonresponse to pharmacotherapy. Twenty-eight medication-free panic disorder patients entered a 12-week open-label treatment study with mirtazapine. Five-minute HRV recordings were obtained before treatment and were analysed using spectral analysis. The data of 17 patients could be used. The total spectrum and low frequency power of responders to mirtazapine were significantly higher than those of nonresponders. Our findings suggest that nonresponders to short-term mirtazapine treatment are characterized at baseline by a lowered output of the ANS. The results are preliminary in view of the small sample studied.

Considering depression as a consequence of activation of the inflammatory response system

This paper summarizes the possible interrelation between peripheral and/or cerebral inflammation and depression. Often, depression is regarded as a consequence of life events, including disabling diseases. The question addressed here is whether activation of the inflammatory response system (IRS) can cause depression. Epidemiological studies suggest that depression can be precipitated by bacterial or viral infections. In depressed patients, peripheral markers of the IRS are often increased. There is some evidence that some forms of depression are caused by a viral infection of the limbic system. More consistent are the observations that depression in diseases with active cerebral inflammatory processes (e.g. multiple sclerosis, Alzheimer's disease) may concur. Direct evidence of a relation between depression and inflammation was found in post-mortem brain material of patients with a vascular depression. In both inflammatory brain diseases and in depression, a state-dependent increased hypothalamus-pituitary-adrenal axis activity is seen. Animals studies have shown that intact cerebral serotonin systems are required for the activation of the IRS following an endotoxin challenge and that long-term treatment with antidepressants may change such a response. Gender differences between the prevalence of depression and inflammatory diseases are similar, as more females are affected. We hypothesize that cerebral or peripheral activation of the IRS may contribute to the course of some antidepressant treatment-resistant depressions. Clinical trials combining antidepressants and drugs that reduce the activation of the IRS may provide evidence for such proposed depression subtypes.

The prediction of nonresponse to pharmacotherapy in panic disorder: a review

Several effective pharmacotherapeutic treatments exist for panic disorder; however, not all patients respond to treatment: between 20% to 40% are non-responders. Recent studies have reported several predictors of nonresponse to pharmacotherapy. In this review two questions are addressed: is there consensus with respect to predictors of nonresponse and are there any differences between short-term and long-term predictors? In this review both short-term and long-term outcome studies are discussed. Studies were included if at least DSM-III criteria were used and baseline variables were investigated as possible predictor of response, or nonresponse, to pharmacotherapy. Of each clinical predictor, tallies were made of the particular predictors employed and of those predictors that predicted nonresponse. It appears that a long duration of illness and severe agoraphobic avoidance are robust predictors of nonresponse, particularly in long-term studies. Personality disorders, or even personality traits, are possibly the most robust predictors of nonresponse. Several factors appear to be robust predictors of nonresponse: factors that are present before treatment and exert their influence on short-term and long-term treatment outcome. Prospective studies are needed to further investigate these factors and to test whether it is viable to intervene in an attempt to increase treatment response.

Iterative versus filtered backprojection reconstruction for statistical parametric mapping of PET activation measurements: a comparative case study

The significance of task-induced cerebral blood flow responses, assessed using statistical parametric mapping, depends, among other things, on the signal-to-noise ratio (SNR) of these responses. Generally, positron emission tomography sinograms of H(2)(15)O activation studies are reconstructed using filtered backprojection (FBP). Alternatively, the acquired data can be reconstructed using an iterative reconstruction procedure. It has been demonstrated that the application of iterative reconstruction methods improves image SNR as compared with FBP. The aim of this study was to compare FBP with iterative reconstruction, to assess the statistical power of H(2)(15)O-PET activation studies using statistical parametric mapping. For this case study, PET data originating from a bimanual motor task were reconstructed using both FBP and maximum likelihood expectation maximization (ML-EM), an iterative algorithm. Both resulting data sets were statistically analyzed using statistical parametric mapping. It was found, with this dataset, that the statistical analysis of the iteratively reconstructed data confirm the a priori expected physiological response. In addition, increased Z scores were obtained in the iteratively reconstructed data. In particular, for the expected task-related response, activation of the posterior border of the left angular gyrus, the Z score increased from 3.00 to 3.96. Furthermore, the number of statistically significant clusters doubled while their volume increased by more than 50%. In conclusion, iterative reconstruction has the potential to increase the statistical power in H(2)(15)O-PET activation studies as compared with FBP reconstruction.

Movement correction of the kidney in dynamic MRI scans using FFT phase difference movement detection

To measure cortical and medullary MR renograms, regions of interest (ROIs) are placed on the kidney in images acquired using dynamic MRI. Since native kidneys move with breathing, and breath-holding techniques are not feasible, movement correction is necessary. In this contribution we compare three correction methods, based on image matching, phase difference movement detection (PDMD), and cross-correlation, respectively. The PDMD-based method showed the best performance and was able to determine kidney movement in our test series in 68% of the scans with no visible deviation, and in 88% of the scans if a one-pixel deviation is considered acceptable.

The effect of mirtazapine in panic disorder: an open label pilot study with a single-blind placebo run-in period

In this open label pilot study, we studied the efficacy of mirtazapine (Remeron) in panic disorder. Twenty-eight patients with a DSM-IV diagnosis of panic disorder, with or without agoraphobia (10 males/18 females), were included and 19 patients completed the study. The 15-week trial started with a 3-week single-blind placebo run-in period. After this run-in period, the 12-week active treatment phase started. As primary efficacy measures, we studied the decrease in the number of full symptom panic attacks and the number of patients completely free of panic during the last 3 weeks of the study. Seventy-four percent of the patients were considered responders, according to a decrease of at least 50% in panic attack frequency. All primary and secondary efficacy measures showed a significant improvement from the second week of active treatment onwards to endpoint. The main side-effects were different from the usual side-effects in selective serotonin reuptake inhibitors (SSRIs) (initial drowsiness, weight gain and pain in the legs). The results of this open label study in panic disorder suggest that mirtazapine seems to be a fast and effective treatment alternative for SSRIs in panic disorder.

Extraocular light therapy in winter depression: a double-blind placebo-controlled study

BACKGROUND

It has been hypothesized that the circadian pacemaker is phase delayed in seasonal affective disorder, (SAD) winter type, and that the phase advance resulting from morning ocular light accounts for the efficacy of light therapy. Extraocular light has been reported to produce phase-shifts of the human circadian pacemaker. This allows a double-blind, placebo-controlled study of light therapy in SAD.

METHODS

Twenty-nine SAD patients participated. Clinical state was measured on days 1, 8, and 15 of the protocol. From days 4 through 8, 15 patients (4 M, 11 F) received extraocular light by fiberoptic illumination, and 14 (4 M, 10 F) placebo (no light) in the popliteal fossae, from 8 AM to 11 AM. In the evenings of days 3 and 8, the salivary dim light melatonin onset (DLMO) was assessed. Patients completed daily self-ratings on mood, alertness, and sleep.

RESULTS

Both conditions showed a progressive improvement of clinical state over time. Between conditions, no significant differences were observed in clinical scores, the self-ratings on mood and alertness, and in timing of the DLMO before and directly after treatment.

CONCLUSIONS

The response to extraocular light therapy in SAD patients did not exceed its placebo effect. Extraocular light did not induce a phase shift of the circadian pacemaker.

Does frontal normality exist in schizophrenia? A saccadic eye movement study

Many observations have supported the general idea of impaired frontal function in schizophrenia. In particular, neuropsychological studies have shown severe frontal deficits. However, other studies found normal cognitive function in a proportion of patients. Since saccadic tasks also provide an index of frontal function, we examined the presence of frontal deficits in patients by means of both neuropsychological and saccadic tasks, and compared the sensitivity of both approaches for frontal impairment. In addition, we examined the relationship between saccadic and neuropsychological measures. Twenty-four schizophrenic patients and twenty healthy controls completed an extensive neuropsychological battery and three saccadic tasks. Based on the neuropsychological battery alone, 42% of the patients showed frontal deficits, whereas combined use of neuropsychological and saccadic tasks resulted in 79% with frontal deficits. The antisaccade task appeared able to detect frontal deficits in patients who were without frontal impairment on the neuropsychological battery. Saccadic deficits were, however, not necessarily accompanied by deficits on frontal neuropsychological measures. This suggests that the saccadic and neuropsychological tasks used in the present study targeted different frontal functions. This view was supported by the lack of correlations between saccadic and frontal neuropsychological measures.

MR renography by semiautomated image analysis: performance in renal transplant recipients

We evaluated a method of semiautomated analysis of dynamic MR image series in renal transplants. Nine patients were studied twice, with an average time interval of 7 days. MR examination consisted of a run of 256 T1-weighted coronal scans (GE; TR/TE/flip: = 11/3.4/60 degrees; slice thickness = 6 mm; temporal resolution = 2 seconds). Gadolinium-DTPA (0.05 mmol/kg) was injected with an injector pump (5 ml/seconds). MR renographs of the cortex and medulla were obtained by segmentation of the renal transplant and placement of two regions of interest (ROIs) overlying the peripheral and central renal parenchyma. In the first 100 frames of the renographs, analysis of variance (ANOVA) demonstrated significant intraclass correlation coefficients with mean values for the cortex and medulla of 0.47 and 0.59, respectively. We conclude that the procedure is a robust technique that generates meaningful signal curves.

Parsing cognition in schizophrenia using saccadic eye movements: a selective overview

Eye movements provide a behavioural measure of sensorimotor processing and higher cognitive functions of the brain. With the development of novel paradigms that can be used for the study of various cognitive operations, saccadic eye movements in particular, have become increasingly popular. Patients with schizophrenia have neurocognitive impairments that can be readily investigated with these paradigms. From animal, human lesion and neuroimaging studies, the cerebral centres underlying saccadic eye movements have been identified. The areas of the prefrontal cortex include the dorsolateral prefrontal cortex, the frontal eye fields, the supplementary eye fields, and the anterior cingulate cortex. Pathology of saccadic eye movements, therefore, provides information on the functional status of the underlying neural circuitry in brain disorders such as schizophrenia. In this paper, we evaluate: (i) methodological considerations that are central to the design and application of saccadic paradigms; (ii) brain activation that is associated with saccadic paradigms; (iii) recent findings in healthy subjects and schizophrenic patients; (iv) saccadic abnormalities in other psychiatric and neurological disorders and in individuals at risk for developing schizophrenia.

Is the beneficial antidepressant effect of coadministration of pindolol really due to somatodendritic autoreceptor antagonism?

BACKGROUND

We investigated the combination of selective serotonin reuptake inhibitors (SSRIs) with the beta-adrenoceptor/serotonin 1A (5-HT(1A)) antagonist pindolol, based on the concept that 5-HT(1A) receptor blockade would eliminate the need for desensitization of presynaptic 5-HT(1A) receptors and therefore hasten the onset of action and improve the efficacy of SSRIs. However, since pindolol plasma levels after 2.5 mg three times a day are about 60 nmol/L, and the K(i) for the 5-HT(1A) receptor is 30 nmol/L, it is questionable whether pindolol levels in the brain would be sufficient to antagonize 5-HT(1A) receptors. Using microdialysis in the guinea pig, we correlated brain and plasma levels of pindolol with its capability of augmenting paroxetine-induced increases in brain 5-HT levels. In addition, central beta-receptor antagonism of pindolol was studied by investigating blockade of beta-agonist-induced increases in brain cyclic adenosine monophosphate (cAMP) formation.

METHODS

Using microdialysis and jugular vein catheterization, we studied the ability of systemically administered pindolol to antagonize central 5-HT(1A) and beta-adrenoceptors, while simultaneously monitoring pindolol plasma and brain concentrations.

RESULTS

Augmentation of paroxetine-induced increases in extracellular 5-HT levels in the ventral hippocampus was only observed at steady state plasma levels exceeding 7000 nmol/L (concurrent brain levels 600 nmol/L). In contrast, antagonism of beta-agonist-induced increases of brain cAMP levels was already observed at pindolol plasma levels of 70 nmol/L (concurrent brain levels < 3 nmol/L).

CONCLUSIONS

At plasma levels that are observed in patients after 2.5 mg three times a day ( approximately 60 nmol/L), pindolol produces only a partial blockade of presynaptic 5-HT(1A) autoreceptors and does not augment the SSRI-induced 5-HT increase in the guinea pig brain. It is therefore very unlikely that the favorable effects of combining pindolol with SSRIs, as reported in a number of clinical studies, are due to 5-HT(1A) antagonism. Since pindolol completely blocks central beta-adrenoreceptors at clinically relevant plasma levels, it is possible that beta-adrenoceptor antagonism is involved in mediating pindolol's beneficial effects.

Acute and chronic effects of citalopram on postsynaptic 5-hydroxytryptamine(1A) receptor-mediated feedback: a microdialysis study in the amygdala

Microdialysis was used to assess the involvement of postsynaptic 5-hydroxytryptamine(1A) (5-HT(1A)) receptors in the regulation of extracellular 5-HT in the amygdala. Local infusion of the 5-HT(1A) receptor agonist flesinoxan (0.3, 1, 3 microM) for 30 min into the amygdala maximally decreased 5-HT to 50% of basal level. Systemic administration of citalopram (10 micromol/kg) increased 5-HT to 175% of basal level. Local infusion of 1 microM of the 5-HT(1A) receptor antagonist WAY 100.635 into the amygdala augmented the effect of citalopram to more than 500% of basal 5-HT level. 5-HT(1A) receptor responsiveness after chronic citalopram treatment was determined in two ways. First, by local infusion of 1 microM flesinoxan for 30 min into the amygdala, which showed a significant 63% reduction in response (area under the concentration-time curve; AUC) for the citalopram group compared to the saline group. Second, by systemic administration of citalopram (10 micromol/kg), which increased 5-HT to 350% of basal level. The effect was larger than in untreated animals, but more important, local infusion of 1 microM WAY 100.635 into the amygdala now failed to augment the effect of citalopram. Both the flesinoxan and WAY 100.635 data suggest an involvement of postsynaptic 5-HT(1A) receptor-mediated feedback in the amygdala, which diminishes following chronic citalopram treatment.

Social anxiety disorder/social phobia: epidemiology, diagnosis, neurobiology, and treatment

Some anticipatory anxiety is expected on specific occasions such as giving a speech. However, some individuals have an excessive fear of such situations when they are under scrutiny, believing that their performance will cause them embarrassment or humiliation, frequently leading to deliberate avoidance of these situations. This disabling condition has been termed social anxiety disorder. Social anxiety disorder is common, with a lifetime prevalence of 2% to 5%, but is probably underreported. The sufferer often avoids seeking assistance, leading to comorbid mental disorders, greater disability, and an increased risk of suicide. Consequently, a high burden is placed on the patient's caregivers and on society. The diagnosis of social anxiety disorder is aided by the patient's history together with DSM-IV criteria. Research into the neurobiology of social anxiety disorder suggests a dysfunction of postsynaptic serotonin receptors and a hypersensitivity to challenge with caffeine, CO2, and pentagastrin. Neuroimaging studies suggest a dysfunction of the striatal presynaptic dopamine transporter in social anxiety disorder. Clear guidelines for the management of social anxiety disorder, including both pharmacotherapy and psychotherapy, are yet to be established. Selective serotonin reuptake inhibitors (SSRIs) show the most promise for the future, while cognitive-behavioral therapy may also be helpful. In the meantime, physicians should treat social anxiety disorder promptly and aggressively.

Social phobia: diagnosis and epidemiology, neurobiology and pharmacology, comorbidity and treatment

Social phobia is a common disorder associated with significant psychosocial impairment, representing a substantial public health problem largely determined by the high prevalence, and the lifelong chronicity. Social phobia starts in early childhood or adolescence and is often comorbid with depression, other anxiety disorders, alcohol and substance abuse or eating disorders. This cascade of comorbidity, usually secondary to social phobia, increases the disability associated with the condition. The possibility that social phobia may be a trigger for later developing comorbid disorders directs attention to the need for early effective treatment as a preventive measure. The most recent drug class to be investigated for the psychopharmacological treatment of social phobia is the SSRI group for which there is growing support. The other drug classes that have been evaluated are monoamine oxidase inhibitors (MAOIs), benzodiazepines, and beta-blockers. The SSRIs represent a new and attractive therapeutic choice for patients with generalized social phobia. Recently the first, large scale, placebo-controlled study to assess the efficacy of drug treatment in generalized social phobia has been completed with paroxetine. Paroxetine was more effective in reducing the symptoms than placebo and was well tolerated. Many now regard SSRIs as the drugs of choice in social phobia because of their effectiveness and because they avoid the problems of treatment with benzodiazepines or classical MAOIs.

MR renography: an algorithm for calculation and correction of cortical volume averaging in medullary renographs

We evaluated a mathematical algorithm for the generation of medullary signal from raw dynamic magnetic resonance (MR) data. Five healthy volunteers were studied. MR examination consisted of a run of 100 T1-weighted coronal scans (gradient echo; TR/TE 11/3.4 msec, flip angle 60 degrees; slice thickness 6 mm; temporal resolution 2 seconds). Gadolinium-diethylene triamine pentaacetic acid (DTPA; 0. 05 mmol/kg) was injected with an injector pump (5 ml/sec). Medullary MR renographs (MRRs) were calculated for regions of interest with strong and moderate cortical volume averaging (CVA). A reference medullary MRR, devoid of CVA, was obtained. Percentual signal differences between calculated and reference medullary MRRs were estimated for each consecutive scan. Run averaged values of these differences were calculated. Mean values, after subtraction of the resting state signal, were +0.2% (SD 9.7%) and +0.7% (SD 9.0%) for areas with strong and moderate CVA, respectively. We conclude that with this algorithm reliable extraction of medullary MRRs is feasible, providing a unique tool for clinical evaluation of medullary disease. J. Magn. Reson. Imaging 2000;12:453-459.

Zolmitriptan (a 5-HT1B/1D receptor agonist with central action) does not increase symptoms in obsessive compulsive disorder

RATIONALE

Non-selective serotonin (5-HT) receptor agonists like meta-chlorophenylpiperazine and MK-212 have been used to explore the role of 5-HT in obsessive compulsive disorder (OCD). The results of these studies and the findings of autoradiography and neuroimaging studies, pointed to a possible role of the 5-HT1B/1D receptor in the pathophysiology of OCD. Recently the selective 5-HT1B/1D receptor agonist sumatriptan was used to further explore the role of the 5-HT1B/1D receptor in OCD. Equivocal results with respect to the increase of obsessive compulsive symptoms in patients with OCD were reported. In one study a significant increase in plasma growth hormone (GH) concentration was observed, although sumatriptan does not pass the blood-brain barrier.

OBJECTIVES

In order to further explore the role of the 5-HT1B/1D receptor in the pathophysiology of OCD, we performed this study, following the same design as Ho Pian et al. (Psychopharmacology 140:365-370).

METHODS

In the present study we performed a randomized, double-blind, placebo-controlled, cross-over design with zolmitriptan (5 mg per os), a selective 5-HT1B/1D receptor agonist with better brain penetrating properties than sumatriptan.

RESULTS

We could not detect any changes in obsessive compulsive symptoms, mood, or anxiety levels, although we found a (nonsignificant) increase in plasma GH levels.

CONCLUSIONS

Based upon these findings, no evidence was found for a specific role of the 5-HT1B/1D receptor in OCD. It should be noted, however, that challenge studies in OCD are difficult to perform. Perhaps in the future better challenge paradigms will make it possible to further explore the role of specific receptor types in OCD.

Desensitisation of 5-HT autoreceptors upon pharmacokinetically monitored chronic treatment with citalopram

Rats were chronically treated with the selective serotonin re-uptake inhibitor citalopram [1-(3-dimethylaminopropyl)-1-(4-fluorophenyl)-5-phtalancarbonitril ], by means of osmotic minipumps. Using an infusion concentration of 50 mg/ml citalopram, steady-state plasma concentrations of approximately 0.3 mcM citalopram were maintained for 15 days. Citalopram plasma levels dropped below pharmacologically active concentrations 48 h after removal of the minipumps. Although chronic treatment with citalopram did induce an attenuated response by extracellular levels of 5-hydroxytryptamine (5-HT) after systemic administration of the 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), no effect of chronic citalopram treatment was observed when 5-HT(1B) receptor function was evaluated with a local infusion of 5-HT(1B/D) receptor agonist, sumatriptan (3-[2-dimethylamino]ethyl-N-methyl-1H-indole-5methane sulphonamide). Controversially, no augmentation of the increase of 5-HT levels was observed upon systemic administration of citalopram. It is concluded that, although chronic treatment with citalopram does induce desensitisation of 5-HT(1A) receptors, the absence of augmented effects of citalopram on 5-HT levels indicates that other mechanisms compensate for the loss of autoreceptor control.

Augmentation with a 5-HT(1A), but not a 5-HT(1B) receptor antagonist critically depends on the dose of citalopram

Pharmacokinetic and pharmacodynamic parameters of the selective serotonin reuptake inhibitor 1-(3-dimethylaminopropyl)-1-(4-fluorophenyl)-5-phtalancarbonitril (citalopram) were determined in order to find optimal conditions for augmentation of its effect on extracellular serotonin [5-hydroxytryptamine (5-HT)] through blockade of 5-HT(1A) and 5-HT(1B) autoreceptors. Citalopram dose-dependently (0.3-10 micromol/kg s.c.) increased serotonin levels in ventral hippocampus of conscious rats. At plasma levels above approximately 0.15 microM, the effect of citalopram on extracellular 5-HT was augmented by both a 5-HT(1A) [N-[2-[4-(2-mehoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridil) cyclohexa necarboxamide trihydrochloride (Way 100635), 1 micromol/kg s.c.] and a 5-HT(1B) receptor antagonist (2'-methyl-4'-(5-methyl-[1,2, 4]oxadiazol-3-yl)biphenyl-4-carboxylic acid [4-methoxy]-3-(4-methylpiperazin-1-yl)phenyl]amide (GR 127935), 1 micromol/kg s.c.). However, at plasma levels of the selective serotonin reuptake inhibitor below 0.15 microM, the effects of the antagonists diverged viz. the 5-HT(1B) receptor antagonist was still able to potentiate citalopram's effect on extracellular 5-HT, while the 5-HT(1A) receptor antagonist was no longer effective. These results suggest that in contrast to 5-HT(1B) autoreceptors, indirect activation of 5-HT(1A) autoreceptors by citalopram is critically related to the dose of selective serotonin reuptake inhibitor administered. The latter may have consequences for selective serotonin reuptake inhibitor augmentation strategies with 5-HT(1A) receptor antagonists in the therapy of depression and anxiety disorders.

Serotonergic blunting to meta-chlorophenylpiperazine (m-CPP) highly correlates with sustained childhood abuse in impulsive and autoaggressive female borderline patients

BACKGROUND

Disturbances of affect, impulse regulation, and autoaggressive behavior, which are all said to be related to an altered function of the central serotonergic (5-HT) system, are prominent features of borderline personality disorder (BPD). A high coincidence of childhood physical and sexual abuse is reported in these patients. Animal studies indicate that early, sustained stress correlates with a dysfunctional central 5-HT system. Therefore, we hypothesize that sustained traumatic stress in childhood affects the responsivity of the postsynaptic serotonergic system of traumatized BPD patients.

METHODS

Following Axis I, Axis II, and trauma assessment, a neuroendocrine challenge test was performed with the postsynaptic serotonergic agonist meta-chlorophenylpiperazine (m-CPP) in 12 impulsive and autoaggressive female patients with BPD and 9 matched healthy volunteers.

RESULTS

The cortisol and prolactin responses to the m-CPP challenge in BPD patients were significantly lower compared to those in controls. Within the group of patients with BPD, the net prolactin response showed a high inverse correlation with the frequency of the physical (r = -.77) and sexual abuse (r = -.60).

CONCLUSIONS

Our data suggest that severe and sustained traumatic stress in childhood affects the 5-HT system and especially 5-HT(1A) receptors. This finding confirms the data from animal research. The blunted prolactin response to m-CPP appears to be the result of severe traumatization and independent of the BPD diagnosis.

Body temperature and mood variations during forced desynchronization in winter depression: a preliminary report

BACKGROUND

It has been suggested that certain abnormalities (e.g., in phase or amplitude) of the circadian pacemaker underlie seasonal affective disorder.

METHODS

One male seasonal affective disorder patient (blind to the study design) participated in two 120-hour forced desynchrony experiments and was subjected to six 20-hour days, once during a depressive episode and once after recovery. Core body temperature was continuously measured. During wakefulness, the Adjective Mood Scale was completed at 2-hour intervals.

RESULTS

Sleep-wake as well as pacemaker-related variations of mood were found, both when the subject was depressed and when he was euthymic. Compared with recovery, during the depressive episode the circadian temperature minimum and the circadian mood variation showed phase delays of approximately 1 and 2 hours, respectively.

CONCLUSIONS

The data of this first seasonal affective disorder patient, participating in forced desynchrony experiments, may indicate a phase delay of the circadian pacemaker during a seasonal affective disorder episode.

Reduction of noise in medullary renograms from dynamic MR images

Dynamic magnetic resonance images of the kidney can be used to acquire separate renograms of the cortex and medulla. A high-quality cortical renogram can be determined directly from a region of interest (ROI) placed in the cortex. Due to partial volume effects, part of the signal from a ROI placed in the medulla is caused by cortical tissue. By subtracting a fraction of the cortical signal from the cortico-medullary signal, a purer medullary renogram can be obtained. A side effect of this subtraction is an increase in noise level. The noise level increases with larger partial volume fractions. Using a matched image filter, it is possible to exclude those areas from the ROI that have a high partial volume content, thus reducing the amount of cortical signal that has to be separated from the medullary signal. Noise reductions of up to 50% have been achieved in the medullary renogram, with an average reduction of 23%.