Measurement of synaptic density in Down syndrome using PET imaging: a pilot study

Area of Science:

• Neuroscience
• Radiochemistry
• Genetics

Background:

• Down syndrome (DS), caused by trisomy 21, is the leading genetic cause of intellectual disability.
• Positron emission tomography (PET) enables in vivo imaging of synaptic density.
• Investigating synaptic changes in DS is crucial for understanding cognitive deficits.

Purpose of the Study:

• To evaluate the feasibility of using the PET radiotracer [11C]UCB-J to measure synaptic density in adults with Down syndrome.
• To compare synaptic density and brain volumes between low-functioning adults with DS and neurotypical (NT) adults.

Main Methods:

• Acquired PET imaging data using [11C]UCB-J from 4 low-functioning adults with DS and 37 older NT adults.
• Utilized a 10-minute acquisition window for synaptic density calculation (SUVR50-60,CS) due to motion artifacts.
• Analyzed synaptic density in key brain regions and compared regional brain volumes.

Main Results:

• Successful PET imaging and synaptic density measurement in low-functioning adults with DS.
• Significant differences in synaptic density were observed in the hippocampus and cerebral cortex between DS and NT groups.
• Hippocampus and cerebellum volumes also differed significantly between the DS and NT groups.

Conclusions:

• PET imaging with [11C]UCB-J is a viable method for assessing synaptic density in adults with Down syndrome.
• This pilot study establishes a foundation for future research comparing synaptic density across different cognitive statuses in DS.
• Findings highlight potential neurobiological differences in synaptic structure in individuals with DS.