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Updated: Dec 27, 2025
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Diffusion Tensor Imaging Abnormalities in the Uncinate Fasciculus and Inferior Longitudinal Fasciculus in
Julia Bassell1, Siddharth Srivastava2, Anna K Prohl3
1Warren Alpert Medical School of Brown University, Providence, Rhode Island.
Insights
Children with Phelan-McDermid syndrome show altered white matter tracts, specifically the uncinate fasciculus, which may explain social and emotional deficits. Further research in larger cohorts is needed.
Area of Science:
- Neuroimaging
- Neurodevelopmental Disorders
- White Matter Integrity
Background:
- Phelan-McDermid syndrome is a rare genetic disorder.
- Autism spectrum disorder is frequently comorbid with Phelan-McDermid syndrome.
- Understanding neurobiological underpinnings is crucial for Phelan-McDermid syndrome management.
Purpose of the Study:
- Compare white matter tracts (uncinate fasciculus, inferior longitudinal fasciculus) in children with Phelan-McDermid syndrome versus controls.
- Investigate the relationship between autism diagnosis and white matter tract integrity.
- Identify potential neuroimaging biomarkers for Phelan-McDermid syndrome.
Main Methods:
- Diffusion tensor imaging (DTI) tractography was used.
- Longitudinal study design with 24-month follow-up.
- Analysis of uncinate fasciculus and inferior longitudinal fasciculus using validated software.
Main Results:
- Significant decrease in fractional anisotropy of the uncinate fasciculus in Phelan-McDermid syndrome patients.
- Significant increase in mean diffusivity of the uncinate fasciculus in Phelan-McDermid syndrome patients.
- Findings observed in both right and left uncinate fasciculus tracts.
Conclusions:
- Altered uncinate fasciculus integrity may contribute to social and emotional deficits in Phelan-McDermid syndrome.
- The uncinate fasciculus is a potential target for understanding Phelan-McDermid syndrome pathophysiology.
- Replication in larger cohorts is recommended.
Background:
This cohort study utilized diffusion tensor imaging tractography to compare the uncinate fasciculus and inferior longitudinal fasciculus in children with Phelan-McDermid syndrome with age-matched controls and investigated trends between autism spectrum diagnosis and the integrity of the uncinate fasciculus and inferior longitudinal fasciculus white matter tracts.
Methods:
This research was conducted under a longitudinal study that aims to map the genotype, phenotype, and natural history of Phelan-McDermid syndrome and identify biomarkers using neuroimaging (ClinicalTrial NCT02461420). Patients were aged three to 21 years and underwent longitudinal neuropsychologic assessment over 24 months. MRI processing and analyses were completed using previously validated image analysis software distributed as the Computational Radiology Kit (http://crl.med.harvard.edu/). Whole-brain connectivity was generated for each subject using a stochastic streamline tractography algorithm, and automatically defined regions of interest were used to map the uncinate fasciculus and inferior longitudinal fasciculus.
Results:
There were 10 participants (50% male; mean age 11.17 years) with Phelan-McDermid syndrome (n = 8 with autism). Age-matched controls, enrolled in a separate longitudinal study (NIH R01 NS079788), underwent the same neuroimaging protocol. There was a statistically significant decrease in the uncinate fasciculus fractional anisotropy measure and a statistically significant increase in uncinate fasciculus mean diffusivity measure, in the patient group versus controls in both right and left tracts (P ≤ 0.024).
Conclusion:
Because the uncinate fasciculus plays a critical role in social and emotional interaction, this tract may underlie some deficits seen in the Phelan-McDermid syndrome population. These findings need to be replicated in a larger cohort.
