Plasma neurofilament light chain concentration is increased in anorexia nervosa

Anorexia nervosa (AN) is a severe psychiatric disorder with high mortality and, to a large extent, unknown pathophysiology. Structural brain differences, such as global or focal reductions in grey or white matter volumes, as well as enlargement of the sulci and the ventricles, have repeatedly been observed in individuals with AN. However, many of the documented aberrances normalize with weight recovery, even though some studies show enduring changes. To further explore whether AN is associated with neuronal damage, we analysed the levels of neurofilament light chain (NfL), a marker reflecting ongoing neuronal injury, in plasma samples from females with AN, females recovered from AN (AN-REC) and normal-weight age-matched female controls (CTRLS). We detected significantly increased plasma levels of NfL in AN vs CTRLS (median_AN = 15.6 pg/ml, IQR_AN = 12.1-21.3, median_CTRL = 9.3 pg/ml, IQR_CTRL = 6.4-12.9, and p < 0.0001), AN vs AN-REC (median_AN-REC = 11.1 pg/ml, IQR_AN-REC = 8.6-15.5, and p < 0.0001), and AN-REC vs CTRLS (p = 0.004). The plasma levels of NfL are negatively associated with BMI overall samples (β (±se) = -0.62 ± 0.087 and p = 6.9‧10^-12). This indicates that AN is associated with neuronal damage that partially normalizes with weight recovery. Further studies are needed to determine which brain areas are affected, and potential long-term sequelae.