|
|
|||||||||||
James Woolley is a clinical research fellow at the Institute of Psychiatry and an honorary specialist registrar at the Maudsley Hospital, London (Section of Neuroimaging, PO67, Institute of Psychiatry, Denmark Hill, London SE5 8AF, UK. Tel: 020 7848 0369; fax: 020 7848 0956; j.woolley{at}iop.kcl.ac.uk). His research interests include neuroimaging in obsessivecompulsive disorder and early psychosis, and clinical interventions to reduce the impact of pre-psychotic symptoms. Philip McGuire is Professor of Psychiatry and Cognitive Neuroscience and Head of the Section of Neuroimaging at the Institute of Psychiatry, London. His research is focused on neurocognitive processes that are putatively defective in psychosis. He is also Clinical Director of Outreach and Support in South London (OASIS) and of the Voices Clinic, Maudsley Hospital, and an honorary consultant to the Lambeth Early Onset (LEO) service.
| Abstract |
|---|
|
|
|---|
| Exclusion of organic causes |
|---|
|
|
|---|
| Radiological anomalies and abnormalities in schizophrenia |
|---|
|
|
|---|
|
| Costbenefit analyses |
|---|
|
|
|---|
| Box 1 Pathologies for which CT and MRI are useful screening tools Computed tomography
Magnetic resonance imaging
|
However, the cost saving per scan for CT compared with MRI must be balanced against the risk of exposure to ionising radiation and of false-negative reports.
Magnetic resonance imaging is more expensive but provides much better image resolution and, because it does not involve X-rays, there are no risks or contraindications associated with exposure to radiation. In schizophrenia, MRI is indicated in the same circumstances as CT. However, it is better than CT at detecting some pathologies (Box 1
).
| What else would help clinicians? |
|---|
|
|
|---|
Since the landmark demonstration, using CT scanning, of enlarged ventricles in schizophrenia (Johnstone et al, 1976), a host of neuroimaging studies have identified areas of reduced grey matter in the disorder, including the hippocampus, parahippocampal gyrus, cingulate gyrus, insula, thalamus and the prefrontal and temporal cortex (Saykin et al, 1991). These structural studies have been complemented by functional imaging research which has indicated that schizophrenia is particularly associated with altered function in the prefrontal, cingulate and temporal cortex (McGuire & Matsumoto, 2004) and that symptoms such as auditory hallucinations and thought disorder are mediated by these brain regions.
Predicting course
There is evidence that the severity of volumetric abnormalities at first presentation and their subsequent rate of progression are associated with a relatively poor prognosis in schizophrenia. In first-episode patients, smaller cerebellum (Wassink et al, 1999), smaller Sylvian fissure and larger third ventricle (van Os et al, 1995), larger lateral ventricles (DeLisi et al, 1991) and ventriculomegaly and cortical atrophy (Zipursky et al, 1998a) have been found to be predictors of various measures of clinical and social outcome (Ho et al, 2003). More recent studies indicate that, although imaging findings at the time of the first episode may have some predictive value, the change within an individuals brain over time may be a better predictor of clinical outcome. Cahn and colleagues found that MRI abnormalities at baseline had little relation to subsequent course. However, the extent of grey matter loss, as revealed by comparison of follow-up and baseline scans, significantly correlated with clinical outcome (Cahn et al, 2002, 2004).
Predicting response to treatment
Neuroimaging may prove to be helpful in predicting which patients with schizophrenia are most likely to respond to treatment, especially in the first episode. Practical applications have been suggested for over a decade, with neuroimaging as part of a battery of tests (including baseline symptom severity, early reduction in symptom severity, initial subjective response to antipsychotic treatment, brain atrophy on neuroimaging and early changes in plasma homovanillic acid levels) at least partially predicting treatment outcome (Stern et al, 1993). Early studies suggested the predictive value of widely distributed brain changes such as average cortical sulcal width on CT scans (Schröder et al, 1993) or relatively increased grey matter volume on MRI (Zipursky et al, 1998b).
More recently, attempts have been made to make predictions in relation to more specific regions, but the results have been inconsistent. Clinical improvement with clozapine has been found in the presence of structural brain abnormalities such as wide Sylvian fissures, features previously associated with non-responsiveness to conventional antipsychotics (Lauriello et al, 1998). Similarly, Konicki et al(2001) found that patients with the greatest degree of functional improvement at follow-up had significantly less prefrontal sulcal widening on baseline MRI than those whose symptoms remained unchanged. In addition, there was no relationship between clozapine response and general sulcal widening.
Functional imaging studies, especially those using positron emission tomography (PET) to examine receptor occupancy, have been more directly useful, but it is difficult to apply their results to individual patients. They have illustrated the relationship between dopamine D2 receptor occupancy, clinical response and side-effects, for example in first-episode schizophrenia (Kapur et al, 2000). Being able to predict that the likelihood of clinical response, hyperprolactinaemia and extrapyramidal side-effects increases significantly as D2 occupancy exceeds specific thresholds facilitates the selection of the appropriate antipsychotic dose. D2 occupancy can also help explain many of the observed clinical differences between typical and atypical antipsychotics. PET could be used to establish the minimum dose that provides optimal D2 receptor occupancy (instead of titrating the dose according to clinical response and side-effects). However, this is impracticable because of the general unavailability of PET and single photon emission tomography (SPET), the cost (thousands of pounds per scan for PET) and the fact that many patients are too ill to scan. Consequently, this approach is mainly used in research, for example in evaluating the optimal dose of a new antipsychotic.
Neuroanatomy may predict response to electroconvulsive therapy (ECT), with a greater third-ventricle-to-brain ratio correlating with a larger number of treatments required to achieve benefit (Dequardo et al, 1997).
Dose and drug selection
Neuroimaging, and in particular functional techniques such as PET and SPET which measure neuroreceptor occupancy in vivo (Fig. 2
), has bolstered the scientific rationale for moving away from high-dose antipsychotic treatment. These methods have confirmed findings previously suspected from clinical experience and suggested by animal models. Scherer et al(1994) showed that D2 receptor occupancy differs between patients with and without extrapyramidal side-effects. Dopamine PET studies have shown that a receptor occupancy of 65% or higher is needed to achieve an antipsychotic effect, but exceeding 72% causes hyperprolactinaemia and over 78% leads to extrapyramidal side-effects (Tauscher & Kapur, 2001). This translates into the clinically useful concept of response to low-dose antipsychotic treatment, and has allowed approximate dose equivalence between alternative antipsychotics to be calculated (e.g. 5 mg haloperidol per day = risperidone 2 mg = olanzapine 7.5 mg; Kapur et al, 1999). Gold et al(1991) demonstrated that neuroimaging can help to predict other side-effects such as tardive dyskinesia. Patients with tardive dyskinesia had significantly smaller ventricle-to-brain ratios than controls.
|
Relapse prediction
Neuroimaging, in combination with other factors, may highlight the likelihood of relapse. For example, from a host of potential relapse predictors following first-episode schizophrenia or schizoaffective disorder, one of the few positive indicators was hippocampal volume (Robinson et al, 1999).
Identifying risk factors
Within groups of patients in their first psychotic episode, significant deficits have been found in cortical grey matter, temporal lobe grey matter and whole brain volume as well as significant enlargement of the lateral and third ventricles. As these occur in both treatment-naïve and minimally treated individuals (Fannon et al, 2000), it is likely that at least some abnormalities were present before the onset of frank psychosis. Furthermore, unaffected relatives of individuals with schizophrenia show many of the volumetric abnormalities seen in people with the disorder, although generally to a lesser degree (Lawrie et al, 1999). The same applies to individuals with prodromal signs who are at high risk of developing psychosis. Within this at-risk group, the severity of the abnormalities may be greater in those who develop psychosis than in those who do not (Pantelis et al, 2003). In addition, the development of psychosis in vulnerable individuals appears to be associated with progressive changes in baseline MRI abnormalities (Pantelis et al, 2003; Job et al, 2004). These observations raise the possibility that neuroimaging may provide a means of identifying the subgroup within a population at high risk who are especially likely to develop psychosis. This would be of great clinical utility. Consequently, any clinical intervention intended to reduce the risk of transition has to be applied to the entire group, raising ethical concerns about unnecessary treatment (McGuire, 2002).
Since disturbances of regional brain function may be evident before macroscopic loss of grey matter, functional imaging may be a more sensitive means of detecting such differences than structural imaging. However, to date there have been few studies of this type and various neuroimaging techniques (e.g. fMRI, PET, psychopharmacological challenge such as tryptophan depletion) are being adapted to explore this.
| Future directions |
|---|
|
|
|---|
Neuromorphometry, involving the manual selection of a particular region of interest and measurement of the overall size or volume of that structure, is the basis of much research. Newer approaches also examine shape, which can change without major alterations in size or volume. Csernansky et al(1998) showed that, although overall and regional brain volume is smaller in people with schizophrenia than in controls, there are many confounding variables such as individuals height and gender. However, they found that measuring the shape of the hippocampus provided a more robust means of differentiating patients from controls (successful in about 70% of cases). Combining shape measures from more than one region (e.g. the hippocampus and pulvinar, a part of the thalamus) appears to increase the sensitivity of this approach (Csernansky et al, 2004).
Broadening the phenotype beyond strict DSM or ICD schizophrenia may help to reveal more primary mechanisms, allowing more probabilistic predictions for individual clinical patients. The study of intermediate phenotypes (identified symptomatically or genetically) is shedding light on the role of global and regionally specific dysfunction (Callicott, 2003), so the future holds promise that a risk profile for individual patients may be defined as advances tie fMRI abnormalities to gene function. Already, relationships between gene function and neuroimaging results have been seen in small samples of individuals with intermediate phenotypes whose behaviour or neuropsychological profile does not necessarily differ from those of healthy controls, emphasising the potential power of such an approach at last to begin giving us useful information about genetic variation in individuals (Hariri & Weinberger, 2003).
Attempts are also being made to exploit the potential statistical power of combining large numbers of scan datasets derived from both research and clinical practice (Governing Council of the Organisation for Human Brain Mapping, 2001). By comparing the results of such analyses with data from individual patient scans, some of the more subtle abnormalities seen in research findings might be more robustly applicable to individual clinical cases.
| The wider context |
|---|
|
|
|---|
We already have some pretty effective treatments... The frustrating thing is that even though we know how to treat many of these disorders, there are still many, many people ... who are not getting treatment. Theres a gap between what we know how to do and what actually happens in the real world. ... Part of [making sure that these treatments are delivered] a very important part involves reducing the stigma of mental disease (Neuroscience Quarterly, 2003).
Although clearly not a justification in itself, we have found that neuroimaging can help reduce this gap for patients, and it is hard to exaggerate the impact that a brain scan image has in an increasingly medicalised society driven by visual media.
Reintegrating psychiatric practice into mainstream medicine is appealing to many, and in its broad application neuroimaging may help this process. However, there is often the temptation to think that neuroimaging is only of use if one concentrates exclusively on biological theories of psychopathology. We suggest it has a role in broader models too, for example in stress-vulnerability concepts of psychosis, where it can inform on events in the earliest stages (Pantelis et al, 2003), or in illuminating the nature of subtle neurodevelopmental abnormalities acting as predisposing factors for subsequent illness (Dazzan et al, 2004). It is encouraging to see neuroimaging taking this broad approach, and the manner in which it can be adapted to complement other approaches (e.g. using genetics and neuropsychology) means that it is likely to teach us more about schizophrenia and become even more clinically relevant.
In summary, it seems that the most promising areas in which research imaging will translate into clinically useful scanning are likely to be: baseline MRI at first episode, in order to exclude other disorders and to predict outcome; serial scanning during the first few years of psychosis, to categorise rate of progression and thus predict outcome; and scanning at-risk individuals to facilitate estimation of the risk of transition to full-blown psychosis and so decide whom to treat.
| MCQs |
|---|
|
|
|---|
|
| Footnotes |
|---|
| References |
|---|
|
|
|---|
Cahn, W., Pol, H. E., Lems, E. B., et al (2002) Brain volume changes in first-episode schizophrenia: a 1-year follow-up study. Archives of General Psychiatry, 59, 10021010.
Cahn, W., van Haren, N. E. M., Pol, H. E., et al (2004) Progressive brain volume changes in the first year of illness predict five-year outcome of schizophrenia. Schizophrenia Research, 67 (suppl. 1), 25.[CrossRef]
Callicott, J. H. (2003) An expanded role for functional neuroimaging in schizophrenia. Current Opinion in Neurobiology, 13, 256260.[CrossRef][Medline]
Csernansky, J. G., Joshi, S., Wang, L., et al (1998) Hippocampal morphometry in schizophrenia by high dimensional brain mapping. Proceedings of the National Academy of Sciences of the United States of America, 95, 1140611411.
Csernansky, J. G., Schindler, M. K., Splinter, N. R., et al (2004) Abnormalities of thalamic volume and shape in schizophrenia. American Journal of Psychiatry, 161, 896902.
Connolly, M. & Kelly, C. (2005) Lifestyle and physical health of people with schizophrenia. Advances in Psychiatric Treatment, 11, 125132.
Dazzan, P., Morgan, K. D., Orr, K. G., et al (2004) The structural brain correlates of neurological soft signs in AESOP first-episode psychoses study. Brain, 127, 143153.
DeLisi, L. E., Stritzke, P. H., Holan, V., et al (1991) Brain morphological changes in 1st episode cases of schizophrenia: are they progressive? Schizophrenia Research, 5, 206208.[CrossRef][Medline]
Dequardo, J. R., Tomori, O., Brunberg, J. A., et al (1997) Does neuroanatomy predict ECT response? Progress in Neuropsychopharmacology and Biological Psychiatry, 21, 13391352.[CrossRef][Medline]
Falkai, P. (1996) Differential diagnosis in acute psychotic episode. International Clinical Psychopharmacology, 11 (suppl. 2), 1317.[CrossRef][Medline]
Fannon, D., Chitnis, X., Doku, V., et al (2000) Features of structural brain abnormality detected in first-episode psychosis. American Journal of Psychiatry, 157, 18291834.
Gold, J. M., Egan, M. F., Kirch, D. G., et al (1991) Tardive dyskinesia: neuropsychological, computerized tomographic, and psychiatric symptom findings. Biological Psychiatry, 30, 587599.[CrossRef][Medline]
Gopal, Y. V. & Variend, H. (2005) First-episode schizophrenia: review of cognitive deficits and cognitive remediation. Advances in Psychiatric Treatment, 11, 3844.
Governing Council of the Organisation for Human Brain Mapping (2001) Neuroimaging databases. Science, 292, 16731676.
Hariri, A. R. & Weinberger, D. R. (2003) Imaging genomics. British Medical Bulletin, 65, 259270.
Ho, B. C., Andreasen, N. C., Nopoulos, P., et al (2003) Progressive structural brain abnormalities and their relationship to clinical outcome: a longitudinal magnetic resonance imaging study early in schizophrenia. Archives of General Psychiatry, 60, 585594.
Job, D., Whalley, H. C., Johnstone, E. C., et al (2004) Grey matter changes as people at high risk develop schizophrenia. Schizophrenia Research, 67, 26.
Johnstone, E. C., Crow, T. J., Frith, C. D., et al (1976) Cerebral ventricular size and cognitive impairment in chronic schizophrenia. Lancet, 2, 924926.[CrossRef][Medline]
Kapur, S., Zipursky, R. B. & Remington, G. (1999) Clinical and theoretical implications of 5-HT2 and D2 receptor occupancy of clozapine, risperidone, and olanzapine in schizophrenia. American Journal of Psychiatry, 156, 286293.
Kapur, S., Zipursky, R., Jones, C., et al (2000) Relationship between dopamine D(2) occupancy, clinical response, and side-effects: a double-blind PET study of first-episode schizophrenia. American Journal of Psychiatry, 157, 514520.
Kasai, K., McCarley, R. W., Salisbury, D. F., et al (2004) Cavum septi pellucidi in first-episode schizophrenia and first-episode affective psychosis: an MRI study. Schizophrenia Research, 71, 6576.[CrossRef][Medline]
Kawasaki, Y., Suzuki, M., Nohara, S., et al (2002) Can brain morphological changes be of diagnostic value for psychiatric disorders? A voxel-based morphometric approach. Neuroimage, 16 (suppl. 1), 3738.[CrossRef]
Kerwin, R. W. & Bolonna, A. (2005) Management of clozapine-resistant schizophrenia, Advances in Psychiatric Treatment, 11, 101106.
Konicki, P. E., Kwon, K. Y., Steele, V., et al (2001) Prefrontal cortical sulcal widening associated with poor treatment response to clozapine. Schizophrenia Research, 48, 173176.[CrossRef][Medline]
Lauriello, J., Mathalon, D. H., Rosenbloom, M., et al (1998) Association between regional brain volumes and clozapine response in schizophrenia. Biological Psychiatry, 43, 879886.[CrossRef][Medline]
Lawrie, S. M., Abukmeil, S. S., Chiswick, A., et al (1997) Qualitative cerebral morphology in schizophrenia: a magnetic resonance imaging study and systematic literature review. Schizophrenia Research, 25, 155166.[CrossRef][Medline]
Lawrie, S. M., Whalley, H., Kestelman, J. N., et al (1999) Magnetic resonance imaging of brain in people at high risk of developing schizophrenia. Lancet, 353, 3033.[CrossRef][Medline]
Leask, S. J. (2004) Environmental influences in schizophrenia: the known and the unknown. Advances in Psychiatric Treatment, 10, 323330.
Lubman, D. I., Velakoulis, D., McGorry, P. D., et al (2002) Incidental radiological findings on brain magnetic resonance imaging in first-episode psychosis and chronic schizophrenia. Acta Psychiatrica Scandinavica, 106, 331336.[CrossRef][Medline]
McCreadie, R. G. (2004) Editorial: Schizophrenia revisited. Advances in Psychiatric Treatment, 10, 321322.
McGuire, P. K. (2002) Prodromal intervention: the need for evaluation. Journal of Mental Health, 11, 469470.[CrossRef]
McGuire, P. K. & Matsumoto, K. (2004) Functional neuroimaging in mental disorders. World Psychiatry, 3, 611.
Neuroscience Quarterly (2003) Comments. An interview with Thomas Insel, Director of the National Institute of Mental Health. Neuroscience Quarterly, Spring. http://web.sfn.org/content/Publications/NeuroscienceNewsletter/2003spring/comments.html.
Pantelis, C., Velakoulis, D., McGorry, P. D., et al (2003) Neuroanatomical abnormalities before and after onset of psychosis: a cross-sectional and longitudinal MRI comparison. Lancet, 361, 281288.[CrossRef][Medline]
Robinson, D., Woerner, M. G., Alvir, J. M., et al (1999) Predictors of relapse following response from a first episode of schizophrenia or schizoaffective disorder. Archives of General Psychiatry, 56, 241247.
Rowlands, P. (2004) The NICE schizophrenia guidelines: the challenge of implementation. Advances in Psychiatric Treatment, 10, 403412.
Saykin, A. J., Gur, R. C., Gur, R. E., et al (1991) Neuropsychological function in schizophrenia. Selective impairment in memory and learning. Archives of General Psychiatry, 48, 618624.[Abstract]
Scherer, J., Tatsch, K., Schwarz, J., et al (1994) D2-dopamine receptor occupancy differs between patients with and without extrapyramidal side-effects. Acta Psychiatrica Scandinavica, 90, 266268.[Medline]
Schröder, J., Geider, F. J. & Sauer, H. (1993) Can computerised tomography be used to predict early treatment response in schizophrenia? British Journal of Psychiatry, 163 (suppl. 21), 1315.
Singh, S. P. & Fisher, H. L. (2005) Early intervention in psychosis: obstacles and opportunities. Advances in Psychiatric Treatment, 11, 7178.
Smith, G. N., Flynn, S. W., Kopala, L. C., et al (1997) A comprehensive method of assessing routine CT scans in schizophrenia. Acta Psychiatrica Scandinavica, 96, 395401.[Medline]
Stern, R. G., Kahn, R. S. & Davidson, M. (1993) Predictors of response to neuroleptic treatment in schizophrenia. Psychiatric Clinics of North America, 16, 313338.[Medline]
Tauscher, J. & Kapur, S. (2001) Choosing the right dose of antipsychotics in schizophrenia: lessons from neuroimaging studies. CNS Drugs, 15, 671678.[CrossRef][Medline]
van Os, J., Fahy, T. A., Jones, P., et al (1995) Increased intracerebral cerebrospinal fluid spaces predict unemployment and negative symptoms in psychotic illness. A prospective study. British Journal of Psychiatry, 166, 750758.
Wassink, T. H., Andreasen, N. C., Nopoulos, P., et al (1999) Cerebellar morphology as a predictor of symptom and psychosocial outcome in schizophrenia. Biological Psychiatry, 45, 4148.[CrossRef][Medline]
Weinberger, D. & Hirsch, S. (2003) Schizophrenia (2nd edn). Oxford: Blackwell Science.
Zipursky, R. B., Lambe, E. K., Kapur, S., et al (1998a) Cerebral gray matter volume deficits in first episode psychosis. Archives of General Psychiatry, 55, 540546.
Zipursky, R. B., Zhang-Wong, J., Lambe, E. K., et al (1998b) MRI correlates of treatment response in first episode psychosis. Schizophrenia Research, 30, 8190.[CrossRef][Medline]
This article has been cited by other articles:
![]() |
S J Borgwardt, E-W Radue, K Gotz, J Aston, M Drewe, U Gschwandtner, S Haller, M Pfluger, R-D Stieglitz, P K McGuire, et al. Radiological findings in individuals at high risk of psychosis J. Neurol. Neurosurg. Psychiatry, February 1, 2006; 77(2): 229 - 233. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| British Journal of Psychiatry | Psychiatric Bulletin | All RCPsych Journals |