Neurological soft signs linked to brain structure alterations in schizophrenia
MedWire News: Structural alterations in the cerebello-thalamo-prefrontal network are associated with neurological soft signs (NSS) in patients with schizophrenia, research shows.
"NSS are subtle 'non-localizing' neurological signs, consistently reported in a majority of patients with schizophrenia [and] are associated with minor physical anomalies, cognitive dysfunction, severity of negative symptoms and disorganization, and a poorer response to treatment," explain Marie-Odile Krebs (Hôpital Sainte-Anne, Paric, France) and team.
However, they add: "Their precise neural substrate remains unclear."
To investigate further, the team studied 52 patients (27% women), aged 18-45 years, with first-episode psychosis, of whom 44 had schizophrenia, four had schizophreniform disorder, two had schizoaffective disorder, and two had psychosis not otherwise specified.
All of the participants underwent a comprehensive neurological examination, including the evaluation of 23 NSS using a four-point rating system.
Whole-brain magnetic resonance imaging with voxel-based morphometry (VBM) was used to assess brain structure.
Overall, the patients mean NSS total score was 10.96, with mean subscores for motor integration, sensory integration, and motor coordination of 2.30, 1.70, and 5.70, respectively.
The researchers found that NSS total scores and motor integration subscores were negatively correlated with VBM gray matter map signals of the dorsolateral prefrontal cortices.
No correlations were found between sensory integration subscores and gray matter map signals.
Motor coordination subscores were positively correlated with VBM white matter map signals of the thalami, and negatively correlated with VBM white matter map signals of the cerebellum.
There were no correlations between VBM white matter map signal and NSS total score or motor integration or sensory integration subscores.
The findings remained similar after accounting for age and gender, the researchers note.
Krebs and team conclude in the journal Acta Psychiatrica Scandinavica: "We found significant correlations between neurological dysfunction and variations in the structure of the thalamus, dorsolateral prefrontal cortices, and cerebellum, structures involved in the schizophrenia 'cognitive dysmetria' model."
They add: "Our results reinforce the value of NSS as an intermediate phenotype that could help to homogenize [the] clinical population with schizophrenia and strengthen cognitive dysmetria hypothesis as a core syndrome in, at least some, patients with schizophrenia."
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By Mark Cowen