White matter integrity and symptom dimensions of schizophrenia: A diffusion tensor imaging study

Area of Science:

• Neuroscience
• Psychiatry
• Radiology

Background:

• Impaired white matter connectivity is a hallmark of schizophrenia.
• Schizophrenia symptoms can be grouped into distinct dimensions.
• Previous studies linked specific syndromes to brain structure changes.

Purpose of the Study:

• To investigate the association between core schizophrenia symptom dimensions and white matter integrity.
• To analyze the full spectrum of psychopathological factors in a single patient cohort.
• To correlate specific symptom clusters with fractional anisotropy (FA) in altered white matter tracts.

Main Methods:

• Diffusion weighted imaging (3T MRI) and Scale for the Assessment of Positive Symptoms (SAPS)/Scale for the Assessment of Negative Symptoms (SANS) scores were collected from 26 male schizophrenia patients and 26 healthy controls.
• Tract-Based Spatial Statistics (TBSS) was used to identify group differences in fractional anisotropy (FA).
• Correlations were performed between symptom dimensions and FA values within identified altered white matter tracts.

Main Results:

• Nine white matter tracts showed significant group differences in FA between patients and controls.
• Hallucinations positively correlated with FA in the left uncinate fasciculus and left corticospinal tract.
• Ego-disturbances (passivity phenomena) correlated positively with FA in the right anterior thalamic radiation.
• Positive formal thought disorders (FTD) negatively correlated with FA in the right cingulum bundle.
• Negative symptoms showed a positive association with the right anterior thalamic radiation and a negative association with the right ventral cingulum bundle.

Conclusions:

• This study provides novel insights into the relationship between specific schizophrenia symptom dimensions and white matter integrity.
• Findings were validated by replicating previous results for hallucinations and negative symptoms, and novel findings for FTD and passivity phenomena were identified.
• Vulnerability of specific brain circuits during neurodevelopment may explain the link between particular psychopathological syndromes and white matter anomalies.