A review of MRI findings in schizophrenia

BACKGROUND Numerous in vivo brain imaging studies suggest that cerebral structure is abnormal in schizophrenia, but implicate different regions to varying extents.

METHOD We identified published MRI studies in schizophrenia with searches of the computerised literature and key journals. Reports giving the volumes of cortical structures in people with schizophrenia and controls were included. The percentage differences in volumes were calculated and the median taken as a summary measure for each brain region.

RESULTS Forty relevant studies were identified. The median percentage volume differences revealed overall reductions in the whole brain (3%), temporal lobe (6% left, 9.5% right), and the amygdala/ hippocampal complex (6.5%, 5.5%); and increases in the lateral ventricles (44%, 36%), that were greatest in the body and occipital horns. Segmentation studies suggest that grey matter is reduced but that white matter volumes may actually be increased. In men, substantial reductions were also evident in the amygdala and hippocampus, as well as the largest reductions of all in the parahippocampus (14%, 9%). Few studies gave figures for women alone.

CONCLUSIONS Several brain structures in schizophrenia are affected to a greater extent than expected from overall reductions in brain volume. Further studies are required in affected women, and to try to identify clinical and aetiological associations of these findings.

Brain abnormality in schizophrenia. A systematic and quantitative review of volumetric magnetic resonance imaging studies.

creased effect sizes across studies (effect size for the left hippocampus and amygdala, 0.67; for the right, 0.72), whereas variables such as illness duration, total slice width, magnet strength, the use of the intracranial volume as a covariate, measurement reliability, and study quality did not. No laterality differences were observed in these data. Conclusions: Schizophrenia is associated with a bilateral volumetric reduction of the hippocampus and probably of the amygdala as well. These findings reinforce the importance of the medial temporal region in schizophrenia and are consistent with frequently reported memory deficits in these patients. Future quantitative magnetic resonance imaging studies evaluating the hippocampal volume should measure the hippocampus and amygdala separately and compare the volumetric reduction in these structures to that observed in other gray matter areas. Arch Gen Psychiatry. 1998;55:433-440

Hippocampal Volume Reduction in Schizophrenia as Assessed by Magnetic Resonance Imaging

Background Although many quantitative magnetic resonance imaging studies have found significant volume reductions in the hippocampi of patients with schizophrenia compared with those of normal control subjects, others have not. Therefore, the issue of hippocampal volume differences associated with schizophrenia remains in question. Methods Two meta-analyses were conducted to reduce the potential effects of sampling error and methodological differences in data acquisition and analysis. Eighteen studies with a total patient number of 522 and a total control number of 426 met the initial selection criteria. Results Meta-analysis 1 yielded mean effect sizes of 0.37 (P Conclusions Schizophrenia is associated with a bilateral volumetric reduction of the hippocampus and probably of the amygdala as well. These findings reinforce the importance of the medial temporal region in schizophrenia and are consistent with frequently reported memory deficits in these patients. Future quantitative magnetic resonance imaging studies evaluating the hippocampal volume should measure the hippocampus and amygdala separately and compare the volumetric reduction in these structures to that observed in other gray matter areas.

https://jamanetwork.com/journals/jamapsychiatry/articlepdf/203854/yoa6321.pdf

Hippocampal volume reduction in schizophrenia as assessed by magnetic resonance imaging : A meta-analytic study

Objective—A pilot study of the density of dendritic spines on pyramidal neurons in layer III of human temporal and frontal cerebral neocortex in schizophrenia. Methods—Postmortem material from a group of eight prospectively diagnosed schizophrenic patients, five archive schizophrenic patients, 11 nonschizophrenic controls, and one patient with schizophrenia-like psychosis, thought to be due to substance misuse, was impregnated with a rapid Golgi method. Spines were counted on the dendrites of pyramidal neurons in temporal and frontal association areas, of which the soma was in layer III (which take part in corticocortical connectivity) and which met strict criteria for impregnation quality. Altogether 25 blocks were studied in the schizophrenic group and 21 in the controls. If more than one block was examined from a single area, the counts for that area were averaged. All measurements were made blind: diagnoses were only disclosed by a third party after measurements were completed. Possible confounding aVects of coexisiting Alzheimer’s disease were taken into account, as were the eVects of age at death and postmortem interval. Results—There was a significant (p<0.001) reduction in the numerical density of spines in schizophrenia (276/mm in control temporal cortex and 112/mm in schizophrenic patients, and 299 and 101 respectively in the frontal cortex). An analysis of variance, taking out eVects of age at death and postmortem interval, which might have explained the low spine density for some of the schizophrenic patients, did not aVect the significance of the results. Conclusion—The results support the concept of there being a defect in the fine structure of dendrites of pyramidal neurons, involving loss of spines, in schizophrenia and may help to explain the loss of cortical volume without loss of neurons in this condition, although the eVect of neuroleptic drugs cannot be ruled out. (J Neurol Neurosurg Psychiatry 1998;65:446‐453)

https://jnnp.bmj.com/content/jnnp/65/4/446.full.pdf

Reduced dendritic spine density on cerebral cortical pyramidal neurons in schizophrenia

The MRI scans of 48 schizophrenic patients, fulfilling RDC criteria, were compared to those of 34 healthy controls matched for age, ethnicity and parental social class. The volume of the frontal and anterior parietal lobes was significantly reduced in the schizophrenic group as a result of a selective decrease in cortical volume, with a corresponding increase in the volume of sulcal fluid. Reduction in the volume of the temporal grey matter was more marked on the right, but was not in excess of the loss of volume observed in other areas of the cortex. MRI abnormalities correlated poorly with clinical parameters, although both unemployment and poor pre-morbid adjustment predicted reduced cerebral volume and increased sulcal volume. These results question whether the medial temporal lobes are the only site of structural pathology in schizophrenia.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S003329170002537X

Reduction of cortical volume in schizophrenia on magnetic resonance imaging

The principles and implementation of a method for measurement of blood flow waveforms from X-ray angiography are described. Contrast medium mass values are obtained at multitudinous positions along individual vessels and from numerous images in a time sequence. These values are represented as a matrix of grey levels in a parametric image. This image is normalized to represent contrast medium concentration, and the movement over time of isoconcentration portions of the contrast bolus is recovered to determine blood flow. Preliminary validation has been undertaken using parametric images generated in two ways: synthesis from a computer model of vascular pulsatile flow and analysis of cine-angiograms of physical models (plastic and perspex tubes) carrying known pulsatile flows. Two distinct methods for interrogation of parametric images by digital image processing were employed; both provided accurate flow measurements.

The measurement of blood flow waveforms from X-ray angiography. Part 1: Principles of the method and preliminary validation

Determination of instantaneous and average blood-flow rates from digital angiograms of vessel phantoms using distance-density curves

The development of a computer model is described which will predict the concentration of contrast media (CM) in a blood vessel after the injection of CM and hence predict the angiographic appearances of the vessel. This model is used to calculate parametric images of CM concentration versus time and distance along the vessel for a wide range of experimental parameters. Blood velocity estimates are derived from these images at many points, both along the vessel and over the cardiac cycle. The model will be used to investigate the correct strategy for the injection of CM and to predict the precision of the resulting flow estimates.

Development of a Model to Predict the Potential Accuracy of Vessel Blood Flow Measurements from Dynamic Angiographic Recordings

The validation, by phantom experiments, of a method of measuring volumetric, pulsatile blood flow in vessels of about 4 mm calibre is described. 'Instantaneous' as well as integrated flow is obtained from cine angiograms by digitisation of the images and densitometric analysis in an advanced computer vision analysis system. From 48 frames per second cine, pulsatile flow at any moment between 0 and about 400 ml/min was calculated within about 10 per cent of the electromagnetic flow meter reading. Further improvement is expected. It is proposed to advance to 3D and have the methodology available for clinical use in due course.

D Wicks

Papers

Reduction of cortical volume in schizophrenia on magnetic resonance imaging

The measurement of blood flow waveforms from X-ray angiography. Part 1: Principles of the method and preliminary validation

Determination of instantaneous and average blood-flow rates from digital angiograms of vessel phantoms using distance-density curves

Development of a Model to Predict the Potential Accuracy of Vessel Blood Flow Measurements from Dynamic Angiographic Recordings

Volume flow measurement of pulsatile flow by digitised cine angiography.