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Biomedical subjects

James Warwick

Publications and source records attributed to James Warwick.

9 recordsLinked to original sources

A brain-behaviour initiative for South Africa: the time is right.

BACKGROUND: Many have advocated for science and health research in developing world settings. However, there has been less focus on the value of basic and clinical neuroscience research in this context. The current paper focuses on the relevance of a brain-behaviour research initiative in South Africa. METHODS: Workshops sponsored by the University of Cape Town Research Office and by the National Research Foundation have recently focused on the state of South African basic and clinical neuroscience, and on how to strengthen research in these areas. The context of the discussion included national science and health priorities, as well as local research opportunities. RESULTS: Neuropsychiatric disorders account for the second largest proportion of the burden of disease in South Africa, but receive relatively little research funding. There is a critical need for research, and there are unique research opportunities, in areas such as trauma and resilience, impulsive behaviour (eg violence, sexual risk taking, and substance abuse), and neuroAIDS. Basic, clinical, and systems research can all make important contributions. CONCLUSION: There is a need to apprise policy-makers in developing world countries such as South Africa of the need for increased expenditure on basic and clinical neuroscience research. Local and international collaboration may be useful in increasing research capacity in South Africa, and ultimately in improving mental health services.

Mental Health↗

Beauty and the beast: Psychobiologic and evolutionary perspectives on body dysmorphic disorder.

Body dysmorphic disorder (BDD) is characterized by preoccupation with a defect in appearance. Concepts of beauty play a particularly crucial role in humans' mental and social life, and may have specific psychobiologic and evolutionary underpinnings. In particular, there is a growing literature on the neurocircuitry underpinning the body schema, body image and facial expression processing, and aesthetic and symmetry judgments. Speculatively, disruptions in cognitive-affective processes relevant to judgements about physical beauty lead to BDD.

Adult↗

Single photon emission computed tomography (SPECT) of anxiety disorders before and after treatment with citalopram.

BACKGROUND: Several studies have now examined the effects of selective serotonin reuptake inhibitor (SSRI) treatment on brain function in a variety of anxiety disorders including obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), and social anxiety disorder (social phobia) (SAD). Regional changes in cerebral perfusion following SSRI treatment have been shown for all three disorders. The orbitofrontal cortex (OFC) (OCD), caudate (OCD), medial pre-frontal/cingulate (OCD, SAD, PTSD), temporal (OCD, SAD, PTSD) and, thalamic regions (OCD, SAD) are some of those implicated. Some data also suggests that higher perfusion pre-treatment in the anterior cingulate (PTSD), OFC, caudate (OCD) and antero-lateral temporal region (SAD) predicts subsequent treatment response. This paper further examines the notion of overlap in the neurocircuitry of treatment and indeed treatment response across anxiety disorders with SSRI treatment. METHODS: Single photon emission computed tomography (SPECT) using Tc-99 m HMPAO to assess brain perfusion was performed on subjects with OCD, PTSD, and SAD before and after 8 weeks (SAD) and 12 weeks (OCD and PTSD) treatment with the SSRI citalopram. Statistical parametric mapping (SPM) was used to compare scans (pre- vs post-medication, and responders vs non-responders) in the combined group of subjects. RESULTS: Citalopram treatment resulted in significant deactivation (p = 0.001) for the entire group in the superior (t = 4.78) and anterior (t = 4.04) cingulate, right thalamus (t = 4.66) and left hippocampus (t = 3.96). Deactivation (p = 0.001) within the left precentral (t = 4.26), right mid-frontal (t = 4.03), right inferior frontal (t = 3.99), left prefrontal (3.81) and right precuneus (t= 3.85) was more marked in treatment responders. No pattern of baseline activation distinguished responders from non-responders to subsequent pharmacotherapy. CONCLUSIONS: Although each of the anxiety disorders may be mediated by different neurocircuits, there is some overlap in the functional neuro-anatomy of their response to SSRI treatment. The current data are consistent with previous work demonstrating the importance of limbic circuits in this spectrum of disorders. These play a crucial role in cognitive-affective processing, are innervated by serotonergic neurons, and changes in their activity during serotonergic pharmacotherapy seem crucial.

Adult↗

Single photon emission computed tomography in posttraumatic stress disorder before and after treatment with a selective serotonin reuptake inhibitor.

BACKGROUND: Posttraumatic stress disorder (PTSD) is recognized as a disorder mediated by specific neurobiological circuits. Functional imaging studies using script-driven trauma imagery and pharmacological challenges have documented altered cerebral function (activation and deactivation) in several brain regions, including the amygdala, hippocampus, prefrontal cortex and anterior cingulate. However, the neural substrates of PTSD remain poorly understood and the effect of selective serotonin reuptake inhibition on regional cerebral activity is deserving of further investigation. METHODS: Eleven adult patients (seven men, four women) (mean age+S.D.=33.6+/-9.2 years) with a DSM-IV diagnosis of PTSD, as determined by the Structured Clinical Interview for DSM-IV (SCID-I) and the Clinician-Administered PTSD Scale (CAPS), underwent single photon emission computed tomography (SPECT) with Tc-99m HMPAO pre- and post-8 weeks of treatment with the selective serotonin reuptake inhibitor, citalopram. Symptoms were assessed at baseline and at 2-week intervals with the Clinician-Administered PTSD Scale (CAPS), Montgomery-Asberg Depression Rating Scale (MADRS), and the Clinical Global Impression Scale (CGI). Image analysis of baseline and post-treatment scans was performed using Statistical Parametric Mapping (SPM). RESULTS: Treatment with citalopram resulted in significant deactivation in the left medial temporal cortex irrespective of clinical response. On covariate analysis, a significant correlation between CAPS score reduction and activation in the left paracingulate region (medial prefrontal cortex) was observed post-treatment. No significant pre-treatment differences were observed between responders and non-responders in anterior cingulate perfusion. CONCLUSIONS: These preliminary findings are consistent with clinical data indicating temporal and prefrontal cortical dysfunction in PTSD and preclinical data demonstrating serotonergic innervation of these regions. However, further studies, in particular in vivo receptor imaging studies, are needed to confirm whether these regional abnormalities correlate with clinical features and treatment response.

Adult↗

SPECT imaging of body dysmorphic disorder.

[99mTc]Hexamethylpropylene amine oxime (HMPAO) single photon emission computed tomography (SPECT) brain scans were undertaken in six subjects with body dysmorphic disorder (BDD). The scans showed a broad range of discrepant findings that do not immediately support a view of BDD as resting on either an obsessive-compulsive or affective disorder spectrum. Nevertheless, involvement of parietal regions is consistent with the characteristic altered body perception of BDD. These preliminary data highlight the need for further systematic functional imaging studies of this condition.

Adult↗

Functional brain imaging and pharmacotherapy in trichotillomania. Single photon emission computed tomography before and after treatment with the selective serotonin reuptake inhibitor citalopram.

The neurobiology and pharmacotherapy of trichotillomania has received increasing attention in recent years. Parallels have been drawn between findings in this disorder and those in obsessive-compulsive disorder (OCD). To date, however, there has been little work on the effect of a pharmacotherapeutic intervention on functional brain imaging in trichotillomania. Female patients (n = 10) with DMS-IV diagnostic criteria for trichotillomania were subjected to single photon emission computed tomography (SPECT) with technetium-99m hexamethylpropylene amine oxime (Tc-99m HMPAO) before and after 12 weeks of pharmacotherapy with the selective serotonin reuptake inhibitor (SSRI), citalopram. Pharmacotherapy led to significantly reduced activity in inferior-posterior and other frontal regions. Correlates of hair-pulling symptoms with regional brain activity differed before and after pharmacotherapy. These data are to some extent consistent with work suggesting that trichotillomania, like OCD, is mediated by corticostriatal circuits. Pharmacotherapeutic response to SSRIs in trichotillomania may not be as robust as in OCD. Further research is necessary to determine the neurobiological underpinnings of these differences.

Adult↗

SPECT scans in identical twins with trichotillomania.

SPECT scans of a set of twins with trichotillomania showed that the twin with more severe disease had larger perfusion defects, involving more areas on the scan. Prospective brain imaging studies of twins may provide useful information about the neurobiology of trichotillomania and other obsessive-compulsive spectrum disorders.

Adult↗

Analysis of clinical brain SPECT data based on anatomic standardization and reference to normal data: an ROC-based comparison of visual, semiquantitative, and voxel-based methods.

UNLABELLED: The technique of anatomic standardization and comparison with normal templates is increasingly used in clinical brain SPECT practice and allows automated, operator-independent volume-of-interest (VOI) or voxel-based analysis of whole-brain data. In 2 distinct clinical populations with severe traumatic brain injury and cognitive impairment, this study compared 3 widely available approaches that use normal templates to evaluate SPECT brain perfusion deficits. METHODS: In total, 74 subjects were studied. These included 14 patients with severe, traumatic brain injury (group 1; 10 males, 4 females; mean age +/- SD, 27.6 +/- 8.2 y) and 15 patients with cognitive impairment (group 2; 7 males, 8 females; mean age, 75.8 +/- 8.6 y). These data were compared with those from, respectively, 25 and 20 age- and sex-adjusted healthy volunteers. All data were analyzed in 4 ways. Three semiquantitative statistical algorithms were used: statistical parametric mapping (SPM) using SPM99, brain registration and analysis of SPECT studies (BRASS) using a voxelwise region-growing technique, and a predefined VOI approach. These results were compared with visual analysis based on consensus reading by 3 experienced nuclear medicine physicians. Receiver operating characteristic (ROC) analysis was performed at various statistical cutoffs. Moreover, as a measure of regional agreement, relative regional agreement between methods was assessed. RESULTS: In both study groups, BRASS voxel-based analysis was most accurate, as defined by the area under the ROC curve (0.97 for group 1 and 0.96 for group 2). VOI assessment was slightly more accurate than visual consensus analysis, whereas SPM showed, overall, a lower area under the ROC curve. SPM analysis was also significantly less sensitive at thresholds corresponding to low false-positive fractions. Regional analysis showed 83%-92% agreement between all methods. CONCLUSION: Under clinical conditions, classification of brain SPECT studies can greatly be aided by anatomic standardization techniques and reference to normal data. Under the investigated circumstances, SPM was found to have a lower sensitivity than VOI or voxelwise region-growing techniques, especially at low false-positive fractions.

Adolescent↗