Objective: We have previously demonstrated increased thalamic blood volume and preserved HMRS neuronal metabolite ratios in painful diabetic peripheral neuropathy (P-DPN) . We hypothesised that perfusion measures and neuronal function measured by metabolite ratios may be related. However, as brain metabolite ratios may also be affected by mood disorders, common in P-DPN, this may be a significant confounding factor.
Methods: 52 type 1 diabetes (T1D) subjects (18 P-DPN, 23 DPN, 13 without neuropathy-DM-NN) and 18 healthy volunteers (HV) were recruited. 1HMRS was performed at 3T (Philips, Netherlands) . Single voxel spectra were obtained from a 2.25cm3 (15x10x15mm) volume of interest within the thalamus, TE=135ms, TR=1600ms, NSA=256 using point resolved (PRESS) technique. Metabolite ratios were calculated for choline, Creatine, and N-Acetyl Aspartate (NAA) . MR-DSC images were obtained at 3T using a T2*-weighted technique (TR/TE=1250/35ms; 72 dynamics) to assess the passage of bolus intravenous gadolinium-chelate through the thalamus.
Results: There was significant negative correlation between NAA/Cr (measure of neuronal function) and measures of depression: Hospital Anxiety and Depression Scale R= -0.33 (p=0.01) , Becks Depression Inventory R= -0.25 (p=.048) ; and anxiety: State-Trait Anxiety inventory- State (STAI-S) R= -.37 (p=.002) , STAI- Trait (T) R= -.32 (p=0.01) and Behavioural Inhibition R= -0.25 (p=0.04) . There were no differences in metabolite ratios between groups; and no significant correlations between perfusion measures and metabolite ratios.
Conclusion: This is the first study to show thalamic 1HMRS metabolite ratios are correlated with measures of mood disorders in T1D. The high prevalence of mood disorders in P-DPN and DPN have confounded previous 1HMRS studies and may explain conflicting reports in the literature. The link between neuropathy and mood disorders needs further exploration to understand whether both may arise from a common neurobiological pathway.
M.Greig: None. G.P.Sloan: None. P.Shillo: None. D.Selvarajah: None. I.D.Wilkinson: None. S.Tesfaye: Advisory Panel; Astellas Pharma Inc., Bayer AG, Grünenthal Group, Nevro Corp., Wörwag Pharma GmbH & Co. KG, Speaker's Bureau; Eva Pharma, Pfizer Inc., Viatris Inc.
European Foundation for the Study of Diabetes (EFSD)