Globally Reduced Brain Volume in Rett Syndrome

Area of Science:

• Neuroimaging
• Neurology
• Developmental Disorders

Background:

• Rett syndrome (RTT) is a complex neurodevelopmental disorder.
• Previous studies on RTT brain volumes were limited by sample size and imaging resolution.
• Direct patient:control matching and advanced MRI techniques are needed for accurate volumetric analysis in RTT.

Purpose of the Study:

• To compare global and regional brain volumes in individuals with RTT against two control groups: typically developing (TD) and idiopathic developmental delay (DD).
• To utilize high-resolution MRI and direct patient:control matching for a more robust volumetric assessment.
• To investigate potential neuroimaging markers that could differentiate RTT from DD.

Main Methods:

• A 1:1 age and sex-matched case-control study design was employed.
• Magnetic Resonance Imaging (MRI) scans were analyzed using the PSTAPLE algorithm for precise volumetric quantification.
• Analysis of covariance was used to compare brain volumes, controlling for intracranial cavity volume and age at scan.

Main Results:

• A total of 42 subjects (14 per group) were analyzed, with a mean age of 8.0 years.
• Individuals with RTT exhibited significantly reduced global and regional brain volumes compared to both TD and DD groups.
• Specific reductions included total gray matter (19% vs. TD/DD), occipital, parietal, and temporal cortices, and cerebellar white matter (3.4% vs. DD only).

Conclusions:

• MRI reveals global brain volume reductions in RTT, affecting cortical and subcortical structures uniformly.
• Cerebellar white matter volume may be decreased in RTT compared to individuals with DD.
• Neuroimaging findings suggest that volumetric assessments can help distinguish RTT from idiopathic developmental delay, highlighting the need to account for global volume differences.