GABA and Working Memory in NF1 (tDCS MRS-fMRI)

This study from the University of Manchester looked at whether the inhibitory neurotransmitter GABA explains working memory problems in young people with neurofibromatosis type 1 (NF1), and whether anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) can change GABA levels and brain activity. It was funded through the Francis S. Collins Scholars Program of the Neurofibromatosis Therapeutic Acceleration Program, and the raw MR data, behavioral task data and clinical metadata are held on the NF Data Portal (Synapse).

Composition

The study paper reports 31 adolescents with a clinical or molecular NF1 diagnosis, recruited through an NF clinical research network in northern UK; 15 were male and the mean age was 14.7 years. Eight had a prior ADHD diagnosis and three an autism diagnosis. Each participant was to attend two visits at least a week apart, one with real and one with sham stimulation in randomized order. Twenty-nine completed both visits and two completed one, as COVID-19 lockdowns stopped further visits. The Synapse project also holds n-back and Corsi block task results.

Acquisition

All scans were done on a Philips Achieva 3 T scanner with a 32-channel head coil. Each visit began with a 3D T1-weighted MPRAGE, used to place spectroscopy voxels over the left DLPFC and the occipital cortex. GABA-edited MEGA-PRESS spectra were recorded from both voxels before and after stimulation. During four 6-minute n-back blocks, dual-echo BOLD fMRI was acquired; stimulation ran during the middle two blocks. T2-weighted images were taken at the first visit to screen for tumors. On Synapse the images are stored as Philips PAR/REC files and the spectra as SDAT/SPAR files.

Known limitations

The cohort is small and has no unaffected control group. Several spectra and fMRI runs were excluded from the published analysis for artifacts or head motion. The project page planned 30 participants, while the paper reports 31. Download requires an approved data access request, and approval is limited to named users at one institution.