Initial evidence of abnormal brain plasticity in anorexia nervosa: an ultra-high field study

Abstract

Anorexia Nervosa has been associated with white matter abnormalities implicating subcortical abnormal myelination. Extending these findings to intracortical myelin has been challenging but ultra-high field neuroimaging offers new methodological opportunities. To test the integrity of intracortical myelin in AN we used 7 T neuroimaging to acquire T1-weighted images optimized for intracortical myelin from seven females with AN (age range: 18–33) and 11 healthy females (age range: 23–32). Intracortical T1 values (inverse index of myelin concentration) were extracted from 148 cortical regions at ten depth-levels across the cortical ribbon. Across all cortical regions, these levels were averaged to generate estimates of total intracortical myelin concentration and were clustered using principal component analyses into two clusters; the outer cluster comprised T1 values across depth-levels ranging from the CSF boundary to the middle of the cortical regions and the inner cluster comprised T1 values across depth-levels ranging from the middle of the cortical regions to the gray/white matter boundary. Individuals with AN exhibited higher T1 values (i.e., decreased intracortical myelin concentration) in all three metrics. It remains to be established if these abnormalities result from undernutrition or specific lipid nutritional imbalances, or are trait markers; and whether they may contribute to neurobiological deficits seen in AN.

Widespread drastic reduction of brain myelin content upon prolonged endurance exercise

“…Perhaps the most striking condition of dietary scarcity is anorexia nervosa, a severe psychiatric disorder, affecting predominantly women, in which body energy reserves are depleted following extreme food restriction and disturbances in cognition surrounding eating and weight ( 30 ). Deficits in volumes of both gray matter and white matter myelin content and connectivity are altered in anorexia nervosa as assessed by MRI studies ( 31–35 ). These findings open the question of whether these abnormalities may result from undernutrition and specific lipid nutritional imbalances ( 32, 35 ).…”

“…Deficits in volumes of both gray matter and white matter myelin content and connectivity are altered in anorexia nervosa as assessed by MRI studies ( 31–35 ). These findings open the question of whether these abnormalities may result from undernutrition and specific lipid nutritional imbalances ( 32, 35 ). Interestingly, the genetic architecture of anorexia nervosa shows significant genetic correlations with metabolic (including glycemic) and lipid traits ( 36 ), and therefore, it is conceivable that they impact in the lipid-rich myelin structure and content as well as its contribution to energy expenditure.…”

White matter microstructure in habit and reward circuits in anorexia nervosa: Insights from a neurite orientation dispersion and density imaging study

“…One previous study that investigated white matter myelin content in underweight adolescent girls with AN using T1 relaxometry 58 found evidence for reduced myelin in the cingulate, corticospinal tract, inferior fronto‐occipital fasciculus, and the arcuate fasciculus. Another study utilizing ultra‐high field MRI assessed intracortical myelin in seven underweight adults with AN and 11 healthy comparisons, noting reduced intracortical myelin concentrations, which was cautiously attributed to possible starvation effects 59 …”

“…Another study utilizing ultra‐high field MRI assessed intracortical myelin in seven underweight adults with AN and 11 healthy comparisons, noting reduced intracortical myelin concentrations, which was cautiously attributed to possible starvation effects. 59 …”

“…Another study utilizing ultra-high field MRI assessed intracortical myelin in seven underweight adults with AN and 11 healthy comparisons, noting reduced intracortical myelin concentrations, which was cautiously attributed to possible starvation effects. 59 Effects of undernutrition on myelination have also been demonstrated experimentally in rats. While most have examined the early postnatal period, one study used rats of an approximately equivalent developmental period as human early adolescence; myelin content was reduced as a result of both general undernutrition and protein malnutrition.…”