Reduced pituitary volume with relative T1 shortening correlates with behavior in Prader-Willi syndrome

Prader-Willi syndrome is a complex endocrinological and developmental disorder characterized by hyperphagic, autistic, and obsessive behaviors, which have been considered to primarily originate from hypothalamus-pituitary axis system alterations in the brain. While the pituitary gland has been demonstrated to contribute to behavioral phenotypes associated with neuropeptide, e.g., arginine-vasopressin, the relevant alterations in Prader-Willi syndrome remain unknown. This study aimed to investigate developmental abnormalities in the pituitary gland structures and determine whether the structural abnormalities are associated with behavioral characteristics in Prader-Willi syndrome. In total, 21 Japanese individuals with Prader-Willi syndrome and 31 healthy controls with typical development were included. Compared with the control group, the Prader-Willi syndrome group showed reduced anterior and posterior pituitary volume ratios per total intracranial volume with relative T₁ shortening in an age-associated manner. Moreover, altered volume ratios and signal intensities were negatively correlated with hyperphagia and autistic questionnaire scores but positively correlated with obsessive scores. The findings suggest that structural and functional alterations, in part due to altered hypothalamus-pituitary function, may contribute to the behavior in Prader-Willi syndrome. The imaging-behavior correlates and in vivo neurochemical visualization of the pituitary gland might be potential intrinsic biomarkers for behavioral phenotypes in Prader-Willi syndrome and other neurodevelopmental disorders.