Pathological cerebral blood blow and corpus callosum abnormalities in schizophrenia: relations to EEG mapping and PET data

Dysfunction of transcallosally mediated motor inhibition and callosal morphology in patients with schizophrenia

OBJECTIVE

In order to assess the functional integrity of motor pathways through the corpus callosum (CC) in patients with schizophrenia transcallosally mediated inhibition (TI) of voluntary tonic EMG activity of first dorsal interosseus muscle following ipsilateral focal transcranial magnetic stimulation (fTMS) was investigated. In addition thickness and length of CC were calculated.

METHOD

Twelve patients suffering from schizophrenia and 12 healthy controls were investigated. CC morphology was measured in mid-sagittal MRI-slices. Latency and duration of TI were calculated.

RESULTS

In schizophrenics the duration of TI was significantly prolonged, whereas latencies were not. In addition, a lack of TI was found unilaterally in three patients. Measurements of CC revealed a significantly reduction of the length and thickness in the anterior part of CC in patients.

CONCLUSION

These findings indicate that measurement of TI could be used to detect clinical silent affection of transcallosal motor pathways in schizophrenics. The effect of neuroleptic drugs has to be explored.

A review of MRI findings in schizophrenia

After more than 100 years of research, the neuropathology of schizophrenia remains unknown and this is despite the fact that both Kraepelin (1919/1971: Kraepelin, E., 1919/1971. Dementia praecox. Churchill Livingston Inc., New York) and Bleuler (1911/1950: Bleuler, E., 1911/1950. Dementia praecox or the group of schizophrenias. International Universities Press, New York), who first described 'dementia praecox' and the 'schizophrenias', were convinced that schizophrenia would ultimately be linked to an organic brain disorder. Alzheimer (1897: Alzheimer, A., 1897. Beitrage zur pathologischen anatomie der hirnrinde und zur anatomischen grundlage einiger psychosen. Monatsschrift fur Psychiarie und Neurologie. 2, 82-120) was the first to investigate the neuropathology of schizophrenia, though he went on to study more tractable brain diseases. The results of subsequent neuropathological studies were disappointing because of conflicting findings. Research interest thus waned and did not flourish again until 1976, following the pivotal computer assisted tomography (CT) finding of lateral ventricular enlargement in schizophrenia by Johnstone and colleagues. Since that time significant progress has been made in brain imaging, particularly with the advent of magnetic resonance imaging (MRI), beginning with the first MRI study of schizophrenia by Smith and coworkers in 1984 (Smith, R.C., Calderon, M., Ravichandran, G.K., et al. (1984). Nuclear magnetic resonance in schizophrenia: A preliminary study. Psychiatry Res. 12, 137-147). MR in vivo imaging of the brain now confirms brain abnormalities in schizophrenia. The 193 peer reviewed MRI studies reported in the current review span the period from 1988 to August, 2000. This 12 year period has witnessed a burgeoning of MRI studies and has led to more definitive findings of brain abnormalities in schizophrenia than any other time period in the history of schizophrenia research. Such progress in defining the neuropathology of schizophrenia is largely due to advances in in vivo MRI techniques. These advances have now led to the identification of a number of brain abnormalities in schizophrenia. Some of these abnormalities confirm earlier post-mortem findings, and most are small and subtle, rather than large, thus necessitating more advanced and accurate measurement tools. These findings include ventricular enlargement (80% of studies reviewed) and third ventricle enlargement (73% of studies reviewed). There is also preferential involvement of medial temporal lobe structures (74% of studies reviewed), which include the amygdala, hippocampus, and parahippocampal gyrus, and neocortical temporal lobe regions (superior temporal gyrus) (100% of studies reviewed). When gray and white matter of superior temporal gyrus was combined, 67% of studies reported abnormalities. There was also moderate evidence for frontal lobe abnormalities (59% of studies reviewed), particularly prefrontal gray matter and orbitofrontal regions. Similarly, there was moderate evidence for parietal lobe abnormalities (60% of studies reviewed), particularly of the inferior parietal lobule which includes both supramarginal and angular gyri. Additionally, there was strong to moderate evidence for subcortical abnormalities (i.e. cavum septi pellucidi-92% of studies reviewed, basal ganglia-68% of studies reviewed, corpus callosum-63% of studies reviewed, and thalamus-42% of studies reviewed), but more equivocal evidence for cerebellar abnormalities (31% of studies reviewed). The timing of such abnormalities has not yet been determined, although many are evident when a patient first becomes symptomatic. There is, however, also evidence that a subset of brain abnormalities may change over the course of the illness. The most parsimonious explanation is that some brain abnormalities are neurodevelopmental in origin but unfold later in development, thus setting the stage for the development of the symptoms of schizophrenia. Or there may be additional factors, such as stress or neurotoxicity, that occur during adolescence or early adulthood and are necessary for the development of schizophrenia, and may be associated with neurodegenerative changes. Importantly, as several different brain regions are involved in the neuropathology of schizophrenia, new models need to be developed and tested that explain neural circuitry abnormalities effecting brain regions not necessarily structurally proximal to each other but nonetheless functionally interrelated. (ABSTRACT TRUNCATED)

Functional motor asymmetries correlated with clinical findings in unmedicated schizophrenic patients

Motor asymmetries were investigated in 28 unmedicated schizophrenic in-patients and 32 healthy controls. Of the patients, who were assessed as right-handers by a handedness questionnaire, 46.4% changed their motor laterality in at least one part of the tapping test series, probably because of a decrease of functional hemispheric asymmetry. These patients were characterized by more pronounced psychotic symptoms than those who did not change motor laterality. According to the tapping frequency, two groups of patients could be distinguished: the high- and the low-frequency group. In both groups certain tapping data could be correlated with characteristic clinical features. While the findings in the high-frequency group point to an enhanced activation level of the right hemisphere and appear to be correlated with the onset of positive symptoms and better prognosis, the findings in the low-frequency group may be a reflection of a disturbed function of the left frontal region and seem to be correlated with a gradual chronic development of predominant negative symptoms with worse prognostic implications.

Psychomotor disturbances in psychiatric patients as a possible basis for new attempts at differential diagnosis and therapy. V. Evaluation of psychomotor training programs in depressed patients

Parts I-III of this series used psychometric assessment of motor performance in psychiatric patients and indicated a "psychotic-motor syndrome" (PMS) in schizophrenic and affective psychoses, which was not found in "neurotic"/reactive or healthy persons. Part IV yielded signs of concomitant brain dysfunction in these patients, demonstrated by EEG mapping as well as other (SPECT/PET) neuroimaging methods. Apart from this "basic science" interest into the pathophysiology of endogenous psychoses we engaged in the development of motor training programs using the PMS as "target" syndrome. We hypothesized, that motor training would not only improve disturbed motor behaviour, but ameliorate other symptoms of psychopathology also. These assumptions were supported in the first two independent studies involving n = 45 and n = 31 ICD-9 mono- and/or bipolar endogenous depressed patients, respectively (the studies on schizophrenic patients being reported finally as part VI of this series, along with the final version of our modified motor test battery). Examples of the motor training programs are provided in this paper, although the final version of the complete programs will be published separately for space reasons and for better availability for routine clinical use.

Brain dysfunction in psychiatric patients during music perception measured by EEG mapping: relation to motor dysfunction and influence of neuroleptic drugs

We report here our findings on music perception obtained as a companion study to the investigation with 16-channel EEG mapping in psychiatric patients during motor activation, published recently elsewhere. We decided to add on a study of this functional circuit, since there is evidence that it is disturbed in various psychiatric patient groups (another "functio laesa"). Involved in the study were 23 male and 25 female schizophrenics, 11 male and 18 female non-endogenously depressed patients (not presently under medication, i.e. drug-naive or wash-out period from 1 week to 17 years), 26 male and 37 female endogenously depressed patients (medicated with tri- or tetracyclic antidepressants and/or benzodiazepines; no lithium), and 22 male and 17 female control subjects (i.e. n = 179). We compared resting conditions after a special relaxation procedure with three music perception tasks: (1) a standardised rumba rhythm generated by a keyboard and delivered binaurally by earphones, (2) the same as an arpeggio in D major, and (3) the same as an arpeggio with a tonic-subdominant-dominant cadence. Major results were obtained in the delta and alpha frequency bands, yielding signs of "diffuse hyperactivation", most prominent in schizophrenic males, and not observed to a similar extent in any other patient group or in normal controls. Interestingly, there were major sex differences, yielding a more diffuse EEG activation pattern in normal females than in males and thus possibly obscuring signs of brain function diffusion in female patients. Viewing our broader evidence of similar brain dysfunction when examining motor functional circuits, especially in schizophrenics, these findings provide further evidence of a brain disorganization with lack of laterality/diffusion which may be found in subgroups of these patients and not in other psychiatric disorders. In schizophrenic patients, these EEG signs of "diffuse hyperactivation" on simple motor and/or music stimulation were reduced to nearly normal by neuroleptic medication. The latter finding may contribute to possible clinical applications of EEG mapping, considering the EEG's unique suitability for long-term brain function monitoring. Other neuroimaging methods like SPECT and PET should be used for additional "external validation".