'Simple schizophrenia': a controlled MRI and clinical/neuropsychological study

Negative symptoms of schizophrenia: Trying to answer unanswered research questions

My research has focused on unmet needs in caring for people with schizophrenia. In particular, I focused on negative symptoms, a complex psychopathological dimension of the disorder, with a significant impact on the disease outcome, and not effectively addressed by existing treatments. In the present commentary, I summarize the trajectory of my research activity. I start with the description of my initial attempts to define the role of the dorsolateral prefrontal cortex in the pathogenesis of broadly defined negative symptoms. Then, I report on the evidence that led me to realize that no progress in research on schizophrenia negative symptoms could occur without considering the heterogeneity and complexity of the construct. Finally, I illustrate my attempts to succeed in this direction and the most pressing unsolved issues in this research field.

The neural substrates of neurological soft signs in schizophrenia: a systematic review

Neurological soft signs (NSS) are common in patients with schizophrenia. However, the neural substrates of NSS remain poorly understood. Using legacy PubMed, we performed a systematic review and included studies that assessed NSS and obtained neuroimaging data in patients with a schizophrenia spectrum disorder published up to June 2020. We systematically reviewed 35 relevant articles. Studies consistently implicate the basal ganglia and cerebellum as structural substrates of NSS and suggest that somatomotor and somatosensory regions as well as areas involved in visual processing and spatial orientation may underlie NSS in psychosis spectrum disorders. Additionally, dysfunction of frontoparietal and cerebellar networks has been implicated in the pathophysiology of NSS. The current literature outlines several structural and functional brain signatures that are relevant for NSS in schizophrenia spectrum disorder. The majority of studies assessed gray matter structure, but only a few studies leveraged other imaging methods such as diffusion weighted imaging, or molecular imaging. Due to this, it remains unclear if white matter integrity deficits or neurometabolic alterations contribute to NSS in the illness. While a substantial portion of the literature has been conducted in patients in the early illness stages, mitigating confounds of illness chronicity, few studies have been conducted in antipsychotic medication-naïve patients, which is a clear limitation. Furthermore, only little is known about the temporal evolution of NSS and associated brain signatures. Future studies addressing these pivotal gaps in our mechanistic understanding of NSS will be important.

Neurological Soft Signs Are Associated With Altered White Matter in Patients With Schizophrenia

Neurological soft signs (NSS) are related to grey matter and functional brain abnormalities in schizophrenia. Studies in healthy subjects suggest, that NSS are also linked to white matter. However, the association between NSS and white matter abnormalities in schizophrenia remains to be elucidated. The present study investigated, if NSS are related to white matter alterations in patients with schizophrenia. The total sample included 42 healthy controls and 41 patients with schizophrenia. We used the Neurological Evaluation Scale (NES), and we acquired diffusion weighted magnetic resonance imaging to assess white matter on a voxel-wise between subject statistic. In patients with schizophrenia, linear associations between NES with fractional anisotropy (FA), radial, axial, and mean diffusivity were analyzed with tract-based spatial statistics while controlling for age, medication dose, the severity of the disease, and motion. The main pattern of results in patients showed a positive association of NES with all diffusion measures except FA in important motor pathways: the corticospinal tract, internal capsule, superior longitudinal fascicle, thalamocortical radiations and corpus callosum. In addition, exploratory tractography analysis revealed an association of the right aslant with NES in patients. These results suggest that specific white matter alterations, that is, increased diffusivity might contribute to NSS in patients with schizophrenia.

Simple schizophrenia or disorganisation syndrome? A case report and review of the literature

Simple schizophrenia is a sometimes controversial diagnosis. Here we review the concept with particular reference to its history in diagnostic systems. Using an illustrative real case of a 25-year-old man, we show that there is a need to retain this diagnostic category, which may fit better within proposed dimensional (psychomotor poverty, disorganisation and reality distortion) rather than categorical classifications of schizophrenia. Symptoms of the disorder may be better revealed by functional assessment than by relying on descriptive psychopathology.

[In defence of the diagnosis of simple schizophrenia: reflections on a case presentation]

INTRODUCTION

Since the first case descriptions of dementia praecox (Diem, 1903), the diagnosis of simple schizophrenia has continued to be controversial. The questioning of its descriptive validity and its reliability, as well as its infrequent use, has led to it being eliminated as a sub-type of schizophrenia in the DSM-III. Criteria for the diagnosis of «simple deteriorative disorder» are currently included in the DSM-IV-TR as a disorder requiring more studies for its possible inclusion.

OBJECTIVES

An attempt is made, using a clinical case, to perform a historical review of the concept of simple schizophrenia, and at the same what has led to the reflection on the possible reasons for the controversy, and a potential route to resolve it.

METHODOLOGY

Using a controversial clinical case, which meets ICD-10 clinical criteria for simple schizophrenia (and those of the DSM-IV-TR for the simple deteriorative disorder), we reflect on the symptoms and diagnostic difficulties. A literature review and update on the subjects was also performed.

DISCUSSION

Our patient highlights, by the absence in the clinical picture of the most obvious positive psychotic symptoms, the tendency by psychiatrists to identify the diagnosis of schizophrenia with the presence of the same, at least at some time during its evolution. The use of neuroimaging tests was useful to assess the level of deterioration and prognosis of the patient.

CONCLUSIONS

Considering simple schizophrenia in the differential diagnosis of other chronic deteriorative disorders could increase its recognition in the initial phases. The use of neuropsychological function tests, and looking for typical deteriorative patterns of the schizophrenia spectrum, could help to increase the reliability of the diagnosis.

Prefrontal abnormalities in patients with simple schizophrenia: structural and functional brain-imaging studies in five cases

Simple schizophrenia is an uncommon disorder with unknown pathophysiology, and its position in the current diagnostic system is ambiguous. Brain-imaging studies may help to elucidate its pathophysiology. Five patients fulfilling both ICD-10 criteria for simple schizophrenia and DSM-IV criteria for simple deteriorative disorder underwent computed tomography, magnetic resonance imaging, and single photon emission computed tomography. These scans were assessed individually by visual inspection as well as automatically by comparison with scans in normal controls or other schizophrenia subtype patients using voxel-based image analyses. Three of the five simple schizophrenia patients had findings of atrophy and reduced cerebral perfusion in the frontal areas. Voxel-based analyses also showed prefrontal grey matter deficits and hypoperfusion in simple schizophrenia patients compared with the controls. Although this study is limited by the small number of patients with simple schizophrenia, the results suggest that simple schizophrenia, or at least this subpopulation, may have rather homogeneous morphological and functional deficits in the prefrontal cortex. It is also suggested that simple schizophrenia may occupy an extreme position of the schizophrenic continuum where the prefrontal deficits and negative symptoms are most purely manifested.

Altered hemispheric asymmetry of auditory magnetic fields to tones and syllables in schizophrenia

BACKGROUND

A growing body of literature suggests that schizophrenic patients often do not show the normal brain hemispheric asymmetry. We have found this for simple tones presented to the right ear in a previous study. In this study we extended this investigation to left ear stimulation and verbal stimuli.

METHODS

With a whole-head neuromagnetometer, contra- and ipsilateral auditory-evoked magnetic fields in response to tones (1000 Hz) and to the syllables ("ba") delivered to the left and right ears in separate runs were compared between schizophrenic patients (n = 17) and healthy control subjects (n = 15).

RESULTS

In response to tones, all control subjects showed the expected asymmetry (contralateral predominance) of the auditory-evoked magnetic N100m (dipole moment). In the patient sample asymmetry was reversed following tones presented to the left ear in 47% and following tones to the right ear in 24%. In response to syllables, the asymmetry was similar between groups. In patients compared with control subjects the N100m was located more anterior without asymmetry between hemispheres.

CONCLUSIONS

Results suggest that deviation from the normal functional lateralization in schizophrenia appears in a proportion of patients at a basic stage of auditory processing, but may be compensated for at higher levels such as the processing of syllables.