Evidence-based guidelines for treating depressive disorders with antidepressants: a revision of the 2000 British Association for Psychopharmacology guidelines

A revision of the 2000 British Association for Psychopharmacology evidence-based guidelines for treating depressive disorders with antidepressants was undertaken to incorporate new evidence and to update the recommendations where appropriate. A consensus meeting involving experts in depressive disorders and their management was held in May 2006. Key areas in treating depression were reviewed, and the strength of evidence and clinical implications were considered. The guidelines were drawn up after extensive feedback from participants and interested parties. A literature review is provided, which identifies the quality of evidence to inform the recommendations, the strength of which are based on the level of evidence. These guidelines cover the nature and detection of depressive disorders, acute treatment with antidepressant drugs, choice of drug versus alternative treatment, practical issues in prescribing and management, next-step treatment, relapse prevention, treatment of relapse, and stopping treatment.

Stress and body shape: stress-induced cortisol secretion is consistently greater among women with central fat

OBJECTIVE

Excessive central fat puts one at greater risk of disease. In animal studies, stress-induced cortisol secretion has been shown to increase central fat. The objective of this study was to assess whether women with central fat distribution (as indicated by a high waist-to-hip ratio [WHR]), across a range of body mass indexes, display consistently heightened cortisol reactivity to repeated laboratory stressors.

METHODS

Fifty-nine healthy premenopausal women, 30 with a high WHR and 29 with a low WHR, were exposed to consecutive laboratory sessions over 4 days (three stress sessions and one rest session). During these sessions, cortisol and psychological responses were assessed.

RESULTS

Women with a high WHR evaluated the laboratory challenges as more threatening, performed more poorly on them, and reported more chronic stress. These women secreted significantly more cortisol during the first stress session than women with a low WHR. Furthermore, lean women with a high WHR lacked habituation to stress in that they continued to secrete significantly more cortisol in response to now familiar challenges (days 2 and 3) than lean women with a low WHR.

CONCLUSIONS

Central fat distribution is related to greater psychological vulnerability to stress and cortisol reactivity. This may be especially true among lean women, who did not habituate to repeated stress. The current cross-sectional findings support the hypothesis that stress-induced cortisol secretion may contribute to central fat and demonstrate a link between psychological stress and risk for disease.

Infrared spectrum of the cool brown dwarf Gl 229B

Spectroscopic measurements of a cool brown dwarf, Gl 229B, reveal absorption features attributable to methane in the near infrared much like those of Jupiter. These features are not seen in any star. The presence of methane indicates that the surface temperature of Gl 229B is below 1000 kelvin. Features attributed to water vapor also indicate that Gl 229B is much cooler than any known star.

Effects of methylphenidate on spatial working memory and planning in healthy young adults

Previous studies of the effects of the psychomotor stimulant, methylphenidate, have concentrated on vigilance and reaction time tasks. In this study, the effects of methylphenidate on more complex aspects of cognition were studied using tasks from the CANTAB battery and related tests which have been shown to be sensitive to frontal lobe dysfunction. Twenty-eight young healthy men participated in a counterbalanced, double-blind, placebo-controlled study of the effects of methylphenidate. Cognitive assessment included tests of spatial working memory, planning, verbal fluency, attentional set-shifting and sustained attention. Methylphenidate had significant effects on performance of the tests of spatial working memory and planning but not on the attentional and fluency tests. When the drug was taken on the first test session, performance on the spatial tests was enhanced by the drug compared to placebo. However, when the drug was taken second, performance accuracy was impaired whereas response latencies were decreased. These results are consistent with a hypothesis that methylphenidate influences performance in two conflicting ways; enhancing executive aspects of spatial function on novel tasks but impairing previously established performance. This pattern of effects is discussed within the framework of dual, interacting arousal mechanisms.

Tryptophan depletion impairs stimulus-reward learning while methylphenidate disrupts attentional control in healthy young adults: implications for the monoaminergic basis of impulsive behaviour

RATIONALE

Altered serotonergic and dopaminergic function have been widely implicated in behavioural disorders associated with impulsivity and risk-taking. However, little research has addressed the specific cognitive consequences of changed monoaminergic function that might contribute to the production of impulsive behaviour.

OBJECTIVES AND METHODS

We compared the effects of rapid plasma tryptophan depletion, acute doses of the mixed indirect catecholamine agonist, methylphenidate (40 mg), and acute doses of the alpha(1)/alpha(2 )agonist, clonidine (1.5 microg/kg), on aspects of visual discrimination learning involving either acquisition of altered stimulus-reward associations (i.e. updating the affective valence of exteroceptive stimuli) or the control of attention towards relevant as opposed to irrelevant stimulus dimensions.

RESULTS

Relative to subjects who received placebo, subjects with reduced tryptophan exhibited a deficit in the ability to learn changed stimulus-reward associations, but were still able to shift an acquired attentional set away from a now-irrelevant stimulus dimension towards a newly relevant dimension. By contrast, subjects who received methylphenidate were able to learn effectively about changing stimulus-reward associations, but showed an enhanced ability to shift an attentional bias, in combination with slowed response times. Subjects who received clonidine showed neither of these changes.

CONCLUSIONS

These results suggest that reduction in central serotonin leads to altered neuromodulation of the cortical and subcortical regions (e.g. orbitofrontal cortex, striatum and anterior temporal structures) that mediate important aspects of associative learning whereby exteroceptive stimuli acquire altered incentive motivational value. On the other hand, facilitation of catecholamine neurotransmitters may disrupt the allocation of attention between relevant and irrelevant features of the environment, perhaps through altered modulation of the dorsolateral prefrontal cortex. The implications of these results for understanding the differential neuromodulation of cognitive functions are discussed.

The NGF-inducible SCG10 mRNA encodes a novel membrane-bound protein present in growth cones and abundant in developing neurons

We have characterized and sequenced cDNA clones corresponding to the neural-specific SCG10 mRNA. The predicted amino acid sequence is novel and not strongly homologous to that of any known polypeptide. The protein is encoded by two mRNAs that differ in their choice of polyadenylation site. Immunocytochemical localization experiments using an affinity-purified antibody (against an SCG10-TrpE fusion protein) reveal accumulations of punctate staining in the perinuclear cytoplasm, axons, and growth cones of cultured neurons. SCG10 levels are maximal in the embryonic CNS but are dramatically reduced in the adult. Preliminary cell fractionation experiments suggest that the protein is tightly associated with membranes but is not itself an integral membrane protein. The apparent localization and timing of expression of the SCG10 protein are reminiscent of GAP-43, but the sequences of the two polypeptides are unrelated. Cross-hybridizing mRNAs and antigenically related proteins are found in several nonneuronal cell lines that do not express SCG10.

Chronic mild stress and sucrose consumption: validity as a model of depression

Sucrose consumption and preference were examined in rats subjected to a 6-week regimen of unpredictable mild stressors, after Willner et al. (11). These subjects were compared with groups exposed to: 1. only the food deprivation element of the stress protocol; or 2. the stress protocol without the food deprivation element. A control group was not exposed to stressors. Body weight and sucrose consumption were significantly reduced in stressed and food-deprived animals compared to the other 2 groups. These variables therefore appeared dependent on food deprivation and independent of other elements of the stress protocol. Neither sucrose consumption per gram body weight nor sucrose preference differed significantly among the 4 groups. These results indicate that food deprivation is not only necessary, but sufficient, to produce sucrose consumption deficits in rats. It is, therefore, likely that reduced sucrose consumption in stressed rats results solely from diminished body weight rather than exposure to the series of stressors. We conclude that sucrose consumption is not a valid index of reward responsiveness. Other measures (such as place-preference conditioning or intracranial self-stimulation threshold) should be evaluated also with respect to body weight change when considering the validity of stressor-based models of depressive disorder.

Evidence-based guidelines for management of attention-deficit/hyperactivity disorder in adolescents in transition to adult services and in adults: recommendations from the British Association for Psychopharmacology

Attention-deficit/hyperactivity disorder (ADHD) is an established diagnosis in children, associated with a large body of evidence on the benefits of treatment. Adolescents with ADHD are now leaving children's services often with no readily identifiable adult service to support them, which presents problems as local pharmacy regulations often preclude the prescription of stimulant drugs by general practitioners (GPs). In addition, adults with ADHD symptoms are now starting to present to primary care and psychiatry services requesting assessment and treatment. For these reasons, the British Association for Psychopharmacology (BAP) thought it timely to hold a consensus conference to review the body of evidence on childhood ADHD and the growing literature on ADHD in older age groups. Much of this initial guidance on managing ADHD in adolescents in transition and in adults is based on expert opinion derived from childhood evidence. We hope that, by the time these guidelines are updated, much evidence will be available to address the many directions for future research that are detailed here.

Disability, distress and unemployment in neurology outpatients with symptoms 'unexplained by organic disease'

OBJECTIVES

To determine the disability, distress and employment status of new neurology outpatients with physical symptoms unexplained by organic disease and to compare them with patients with symptoms explained by organic disease.

METHODS

As part of a cohort study (the Scottish Neurological Symptoms Study) neurologists rated the extent to which each new patient's symptoms were explained by organic disease. Patients whose symptoms were rated as 'not at all' or only 'somewhat' explained by disease were considered cases, and those whose symptoms were 'largely' or 'completely' explained by disease were considered controls. All patients completed self-ratings of disability, health status (Medical Outcomes Study Short Form 12-Item Scale (SF-12)) and emotional distress (Hospital Anxiety and Depression Scale) and also reported their employment and state financial benefit status.

RESULTS

3781 patients were recruited: 1144 (30%) cases and 2637 (70%) controls. Cases had worse physical health status (SF-12 score 42 vs 44; difference in means 1.7 (95% CI -2.5 to 0.9)) and worse mental health status (SF-12 score 43 vs 47; difference in means -3.5 (95% CI -4.3 to to 2.7)). Unemployment was similar in cases and controls (50% vs 50%) but cases were more likely not to be working for health reasons (54% vs 37% of the 50% not working; OR 2.0 (95% CI 1.6 to 2.4)) and also more likely to be receiving disability-related state financial benefits (27% vs 22%; (OR 1.3, 95% CI 1.1 to 1.6)).

CONCLUSIONS

New neurology patients with symptoms unexplained by organic disease have more disability-, distress- and disability-related state financial benefits than patients with symptoms explained by disease.

A comprehensive assessment of memory, delay aversion, timing, inhibition, decision making and variability in attention deficit hyperactivity disorder: advancing beyond the three-pathway models

BACKGROUND

Although attention deficit hyperactivity disorder (ADHD) has been associated with a broad range of deficits across various neuropsychological domains, most studies have assessed only a narrow range of neuropsychological functions. Direct cross-domain comparisons are rare, with almost all studies restricted to less than four domains. Therefore, the relationships between these various domains remain undefined. In addition, almost all studies included previously medicated participants, limiting the conclusions that can be drawn. We present the first study to compare a large cohort of medication-naive boys with ADHD with healthy controls on a broad battery of neuropsychological tasks, assessing six key domains of neuropsychological functioning.

METHOD

The neuropsychological functioning of 83 medication-naive boys with well-characterized ADHD (mean age 8.9 years) was compared with that of 66 typically developing (TYP) boys (mean age 9.0 years) on a broad battery of validated neuropsychological tasks.

RESULTS

Data reduction using complementary factor analysis (CFA) confirmed six distinct neuropsychological domains: working memory, inhibition, delay aversion, decision making, timing and response variability. Boys with ADHD performed less well across all six domains although, for each domain, only a minority of boys with ADHD had a deficit [effect size (% with deficit) ADHD versus TYP: working memory 0.95 (30.1), inhibition 0.61 (22.9), delay aversion 0.82 (36.1), decision making 0.55 (20.5), timing 0.71 (31.3), response variability 0.37 (18.1)].

CONCLUSIONS

The clinical syndrome of ADHD is neuropsychologically heterogeneous. These data highlight the complexity of the relationships between the different neuropsychological profiles associated with ADHD and the clinical symptoms and functional impairment.

Sucrose consumption as an hedonic measure following chronic unpredictable mild stress

The consumption of, and preference for, a rewarding 0.9% sucrose solution was examined in rats subjected chronically (8 wk) to a regimen of unpredictable mild stressors. Intake of sucrose was reduced in stressed animals compared to controls after 3 wk. However, correction for body weight changes revealed no significant difference in sucrose consumption between the groups. A comparison of the mean sucrose intakes of matched low-weight rats, with low weight a function of either immaturity or stress, failed to differentiate between the groups. Total sucrose consumption and total fluid intake correlated significantly with body weight of stressed animals and controls. Percentage preference for sucrose solution did not differ between controls and stressed animals. It is concluded that the validity and reliability of sucrose consumption as an hedonic measure within the context of exposure to chronic unpredictable mild stress must be questioned.

Estrogen replacement therapy and cognitive decline in older community women

BACKGROUND

The purpose of this study was to evaluate the cross-sectional and longitudinal association of oral estrogen replacement therapy (ERT) and cognitive function in an older, nondemented sample of women.

METHODS

In a prospective cohort of 9651 white women aged 65 years and older enrolled in the Study of Osteoporotic Fractures, a modified Mini-Mental Status Exam (mMMSE), and digit symbol substitution and Trails B tests were administered twice, 4 to 6 years apart. History and current use of oral ERT was documented. Age, educational attainment, and activity limitations were the primary covariates in the analyses; in addition, stroke and depression scores were adjusted in subsets of women with available data.

RESULTS

Current and past users of ERT had better initial scores on the mMMSE than did never users, P < .05 and .001, respectively, with better scores for current estrogen hormone users being most apparent among the older and less educated women. The percentages of women scoring < or = 23 of a possible 26 on the mMMSE were 14.3 for current users, 14.5 for past users, and 20.5 for never users, P < .001. However, only past users exhibited smaller declines upon retesting in mMMSE and Trails B performance, P < .05, than did never users. Educational attainment predicted both initial test scores and change scores and was, next to age, the most powerful predictor of cognitive function.

CONCLUSIONS

Current oral ERT does not protect against age-related declines in cognitive function in older nondemented women, whereas formal education does protect, even though it had been completed many years earlier. The influence of education in late-life on cognitive function should be tested.

Periodic maternal separation of neonatal rats produces region- and gender-specific effects on biogenic amine content in postmortem adult brain

Early environment exerts profound effects on mammalian behavioral and neural development. The aim of this study was to describe changes in adult neurochemistry in the rat following repeated neonatal maternal separation (RMS) during the preweaning period, a procedure known to induce enduring behavioral effects. Following RMS, rats show an attenuated locomotor response to novelty, to D-amphetamine, and attenuated behavioral responses for conditioned incentives as adults. These behavioral effects are broadly opposite in direction to those found following postweaning isolation rearing. Isolation rearing-induced behavioral changes are associated with profound changes in central monoamine function. Following RMS, adult rats had increased tissue levels of dopamine in both dorsal and ventral striatum. The turnover of dopamine, as determined by the ratio of DOPAC to dopamine, was decreased in the mPFC of RMS subjects. Serotonin levels were reduced in dorsal hippocampus of RMS rats of both sexes and in the mPFC of male RMS rats. Noradrenaline levels were increased in the dorsal hippocampus in female, but not in male, RMS rats. These data provide evidence that, in addition to the adult behavioral consequences, RMS leads to profound, region-, and gender-specific changes in brain monoamine content. The developmental specificity of these results is discussed with respect to their possible role in altered behavioral development and psychopathology.

Association of hostility with coronary artery calcification in young adults: the CARDIA study. Coronary Artery Risk Development in Young Adults

CONTEXT

Psychosocial factors, including personality and character traits, may play a role in the development and expression of coronary artery disease.

OBJECTIVE

To evaluate whether hostility, a previously reported predictor of clinical coronary artery disease, is associated with coronary calcification, which is a marker of subclinical atherosclerosis.

DESIGN

Prospective cohort study.

SETTING AND PARTICIPANTS

Volunteer subsample from Chicago, Ill, and Oakland, Calif, consisting of 374 white and black men and women, aged 18 to 30 years at baseline, who participated in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Cook-Medley hostility assessment data were collected at baseline from 1985 to 1986 and at year 5 examinations from 1990 to 1992. After the 10-year examinations in the 1995-1996 year, electron-beam computed tomographic scans were performed.

MAIN OUTCOME MEASURES

Presence of any detectable coronary artery calcification (coronary calcium score >0), and coronary artery calcium scores of 20 or higher.

RESULTS

In logistic regression analysis adjusting for age, sex, race, and field center comparing those with hostility scores above and below the median of the distribution of the present sample, the odds ratio of having any coronary calcification was 2.57 (95% confidence interval, 1.31-5.22), and the odds ratio of having a calcium score of 20 or higher was 9.56 (95% confidence interval, 2.29-65.9) for calcium scores of 20 or higher. The associations with any coronary artery calcification persisted after adjusting for demographic, lifestyle, and physiological variables. Results using a cynical distrust subscale were somewhat weaker than for those using the global hostility score. Power was inadequate to perform sex- or race-specific analyses.

CONCLUSION

These results suggest that a high hostility level may predispose young adults to coronary artery calcification. JAMA. 2000;283:2546-2551

Repeated maternal separation of preweanling rats attenuates behavioral responses to primary and conditioned incentives in adulthood

Early social experience has profound effects on a wide spectrum of behaviors and neurochemical correlates in the rat. Repeated separation of rat pups from their dam during the early neonatal period causes acute perturbation of neuroendocrine and physiological status. The chronic sequelae of repeated separations have not been studied as extensively as the acute responses. Altered social experience at a later developmental stage, postweaning isolation rearing, is known to induce enduring changes in the behavioral responses to reward and reward-related stimuli in maturity. We have evaluated the influence of repeated early maternal separation on the responses to both primary and conditioned incentives in mature rats. Separated animals showed enhanced weight gain, a blunted locomotor response to a novel environment and a blunting of the response to both negative and positive contrast effects. Female separated animals, but not males, exhibited a profound attenuation of the acquisition of a conditioned anticipatory locomotor response to the presentation of food. These data are discussed with respect to the putative involvement of ventral striatal dopamine systems in reward mechanisms and the potential utility of early maternal separation as an animal model of depression.

Repeated neonatal maternal separation alters intravenous cocaine self-administration in adult rats

Behavioural responses to psychostimulant drugs can be profoundly affected by early environmental influences. The aim of this study was to describe the effects of repeated brief separations of rat pups from their dams during the early neonatal period on cocaine self-administration behaviour as adults. Lister hooded rats exposed to a repeated maternal separation procedure (REMS) showed altered acquisition and maintenance of cocaine self-administration as adults, the effects being dose and gender-dependent. Overall, the patterns of acquisition of self-administration across three doses of cocaine (0.05, 0.08 and 0.5 mg/injection) suggested a rightward shift in the acquisition dose-effect functions for the REMS animals relative to control animals. At 0.05 mg/injection, there was a retarded acquisition of cocaine self-administration in male and female neonatally separated rats. At 0.08 mg/injection there was a facilitated acquisition in female neonatally separated subjects. After establishment of stable self-administration of the training dose, in the same cohort of subjects, rightward and downward shifts in the cocaine self-administration dose-effect functions were determined for female and male REMS subjects, respectively, relative to their controls. The dose-effect function for both female groups was shifted to the left of that of the respective male groups, although the lighter body weights of the females meant that they administered a higher unit dose per unit body weight than the males. Whereas male REMS subjects tended to self-administer less cocaine than the controls at the dose eliciting maximal responding (0.03 mg/injection) and to make fewer lever responses overall at each dose tested, female REMS subjects self-administered significantly more cocaine than their respective controls at a dose of 0.03 mg/injection. There was no differential sensitivity to the rate-altering effects of the selective dopamine D2 receptor antagonist, eticlopride, or to the selective dopamine D1 receptor antagonist, SCH 23390. These data provide further evidence that altered early environment affects drug-taking behaviour in a developmentally specific and gender-specific manner, with the effects of neonatal separation contrasting with previously published data on the effects of post-weaning isolation rearing.

Effects of scopolamine on delayed-matching-to-sample and paired associates tests of visual memory and learning in human subjects: comparison with diazepam and implications for dementia

Two experiments examined dose-related effects of 200, 400 and 600 micrograms scopolamine (n = 24, s.c.) and 5 and 10 mg diazepam (n = 6, PO) on parallel tests of visual memory and learning taken from the CANTAB battery. Scopolamine significantly impaired accuracy of performance on a delayed matching to sample test of visual recognition memory in a dose- and delay-dependent manner, but had only marginal decremental effects on a test of visuospatial paired associates learning. Scopolamine significantly lengthened decision times in a visual search matching to sample task at the 400 and 600 micrograms doses, without significantly affecting accuracy. The drug also impaired performance on tests of spatial (on accuracy and response time measures) and pattern (on response time only) memory. Most of the deleterious effects on scopolamine were removed by covariance analyses with indices of subjective sedation, but the effects of delayed matching accuracy and latency remained. By contrast, diazepam significantly impaired paired associates learning but affected delayed matching to sample in a delay-independent manner. These results suggest that scopolamine can produce selective deficits in tests of short-term visual recognition memory which do not depend on overall impairments in arousal and which contrast with deficits in visual associative learning produced by diazepam. They have implications for the pharmacological modelling of dementia and memory disorders in man and for the neurochemical substrates of the short-term recognition memory and associative learning for visual stimuli.

A longitudinal examination of neuropsychological and clinical functioning in boys with attention deficit hyperactivity disorder (ADHD): improvements in executive functioning do not explain clinical improvement

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) often, but not always, persists into adulthood. Investigations of the associations between clinical and biological markers of persistence can shed light on causal pathways. It has been proposed that compensatory improvements in executive neuropsychological functioning are associated with clinical improvements. This is the first study to test this hypothesis prospectively.

METHOD

The clinical and neuropsychological functioning of 17 boys with ADHD (mean age 10.45 years at time 1; 14.65 years at time 2) and 17 typically developing (TYP) boys (mean age 10.39 years at time 1; 14.47 years at time 2) was tested on two occasions, 4 years apart. This was done using a battery of standardized neuropsychological tests that included tasks with high and low executive demands.

RESULTS

Clinical improvements were observed over time. Neuropsychological performance improvements were also evident, with ADHD boys developing with a similar pattern to TYP boys, but with a developmental lag. Whilst there was an association between reduced symptoms and superior performance at retest for one task with a high executive demand (spatial working memory), this was not seen with two further high executive demand tasks [Stockings of Cambridge and intra-dimensional extra-dimensional (ID/ED) set shifting]. Also, there was no association between change in executive functioning and change in symptoms. Baseline performance on the ID/ED set-shifting task predicted better clinical outcome. Only change in performance on the low executive demand delayed matching-to-sample task predicted better clinical outcome.

CONCLUSIONS

These data highlight the importance of longitudinal measurements of cognition, symptoms and treatment response over time in children and adolescents with ADHD.

FlyBase: a Drosophila database. The FlyBase consortium

FlyBase is a database of genetic and molecular data concerning Drosophila. FlyBase is maintained as a relational database (in Sybase) and is made available as html documents and flat files. The scope of FlyBase includes: genes, alleles (and phenotypes), aberrations, transposons, pointers to sequence data, clones, stock lists, Drosophila workers and bibliographic references. The Encyclopedia of Drosophila is a joint effort between FlyBase and the Berkeley Drosophila Genome Project which integrates FlyBase data with those from the BDGP.

Evidence of opioid-induced hyperalgesia in clinical populations after chronic opioid exposure: a systematic review and meta-analysis

BACKGROUND

Opioid-induced hyperalgesia (OIH) is well documented in preclinical studies, but findings of clinical studies are less consistent. The objective was to undertake a systematic review and meta-analysis of studies examining evidence for OIH in humans after opioid exposure.

METHODS

Systematic electronic searches utilised six research databases (Embase, Medline, PubMed, CINAHL Plus, Web of Science, and OpenGrey). Manual 'grey' literature searches were also undertaken. The Population, Interventions, Comparators, Outcomes, and Study design (PICOS) framework was used to develop search strategies, and findings are reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. Data synthesis and subgroup analyses were undertaken using a random effects model (DerSimonian-Laird method).

RESULTS

A total of 6167 articles were identified. After abstract and full-text reviews, 26 articles (involving 2706 participants) were included in the review. There was evidence of OIH, assessed by pain tolerance, in response to noxious thermal (hot and cold) stimuli, but not electrical stimuli. There was no evidence of OIH when assessing pain detection thresholds. OIH was more evident in patients with opioid use disorder than in patients with pain, and in patient groups treated with N-methyl-d-aspartate receptor antagonists (primarily evidenced in methadone-maintained populations).

CONCLUSIONS

OIH was evident in patients after chronic opioid exposure, but findings were dependent upon pain modality and assessment measures. Further studies should consider evaluating both pain threshold and pain tolerance across a range of modalities to ensure assessment validity. Significant subgroup findings suggest that potential confounders of pain judgements, such as illicit substance use, affective characteristics, or coping styles, should be rigorously controlled in future studies.

Retarded acquisition and reduced expression of conditioned locomotor activity in adult rats following repeated early maternal separation: effects of prefeeding, d-amphetamine, dopamine antagonists and clonidine

Adult hooded rats exposed to a repeated maternal separation procedure during the neonatal period showed a blunted expression of locomotor hyperactivity conditioned to the presentation of the daily food ration. We have demonstrated that the expression of food-conditioned anticipatory hyperactivity is sensitive to the response-enhancing effects of systemic d-amphetamine (0.5; 1.0 mg/kg) and to the response-attenuating effects of the selective dopamine D2 antagonist sulpiride (8; 20 mg/kg), the selective dopamine D1 antagonist SCH 23390 (0.01; 0.022 mg/kg) and the mixed alpha 1/alpha 2 adrenoceptor agonist clonidine (5; 15 micrograms/kg) in a dose dependent manner. Animals from the early separation groups showed a reduced enhancement of activity in response to 0.5 mg/kg d-amphetamine and a greater attenuation of activity in response to 8 mg/kg sulpiride and 5 micrograms/kg clonidine. Female separated rats also exhibited an attenuated locomotor response to the unconditioned stimulant effects of 0.5 mg/kg systemic d-amphetamine. The experiments confirm that early maternal separation attenuates the response to conditioned appetitive cues in adult rats and implicate altered dopaminergic and noradrenergic function in the changes. It is possible that early maternal separation in the rat may offer a useful preparation for investigation of the neural substrates mediating affective development and affective psychopathology.