Cerebrospinal fluid biomarkers of neurodegeneration in patients with juvenile and classic myotonic dystrophy type 1

Background and purpose The aim of the present study was to analyze cerebrospinal fluid ( CSF ) levels of total tau ( T ‐tau), phosphorylated tau ( P ‐tau) and the 42‐amino‐acid form of β ‐amyloid ( Aβ 42 ) in patients with myotonic dystrophy type 1 ( DM 1), and their possible correlations with cognitive and behavioral manifestations in these patients. Methods Lumbar puncture was performed in 74 patients with DM 1 [27 with the childhood/juvenile form (j DM 1) and 47 with the adult form (a DM 1) of the disease] and 26 control subjects who were subjected to orthopedic surgery. Sandwich ELISA was used for measuring the levels of T ‐tau, P ‐tau and Aβ 42 . Results The CSF level of Aβ 42 was at its lowest in patients with j DM 1 and at its highest in controls ( P  < 0.05). A tendency of T‐tau and P‐tau to increase was greater in aDM1 patients than in jDM1 patients and controls ( P  > 0.05). In both j DM 1 and a DM 1 patients, significant correlations were found between Aβ 42 and T‐tau (rho = 0.81 and rho = 0.67, respectively, P  < 0.01), as well as between Aβ 42 and P‐tau (rho = 0.87 and rho = 0.67, respectively, P  < 0.01). The Aβ 42 /P‐tau ratio decreased with age in a DM 1 patients (rho = −0.30, P  < 0.05). Only the level of Aβ 42 in the CSF of j DM 1 patients was correlated with the size of the CTG expansion (rho = −0.53, P  < 0.05). Only a few correlations were observed between levels of biomarkers and neuropsychological testing. Conclusion The CSF level of Aβ 42 was decreased in patients with j DM 1, whilst the Aβ 42 / P ‐tau ratio was decreased in a DM 1 patients. Positive correlations between Aβ 42 , T ‐tau and P ‐tau were observed in both forms of disease. Further studies with larger cohorts of DM 1 patients are necessary.