Serum glutamine, set-shifting ability and anorexia nervosa

Area of Science:

• Neuroscience
• Biochemistry
• Psychiatry

Background:

• Set-shifting deficits are common in anorexia nervosa (AN), but underlying mechanisms remain unclear.
• Glutamatergic pathways in the prefrontal cortex are crucial for set-shifting in animal models.
• The association between serum glutamatergic amino acids and set-shifting in humans with AN is not well understood.

Purpose of the Study:

• To investigate the relationship between serum concentrations of glutamatergic neurotransmission-related amino acids (glutamine, glutamate, glycine, l-serine, d-serine) and set-shifting ability.
• To compare these amino acid levels and set-shifting performance in individuals with acute AN, recovered AN, and healthy controls.

Main Methods:

• Serum amino acid concentrations were measured in 27 women with acute AN, 18 recovered women (ANRec), and 28 healthy controls (HC).
• Set-shifting was assessed using the Wisconsin Card Sorting Test (WCST) and Trail Making Task (TMT).
• Psychopathology was evaluated using the Eating Disorder Examination Questionnaire (EDEQ), Maudsley Obsessive-Compulsive Inventory (MOCI), and Hospital Anxiety and Depression Scale (HADS).

Main Results:

• Serum glutamine concentrations were significantly higher (approx. 20%) in the AN group compared to the HC group.
• Higher serum glutamine levels correlated with greater illness severity, including lower body mass index (BMI) and longer illness duration.
• Individuals with AN exhibited significantly impaired set-shifting on the WCST, but serum glutamine levels did not correlate with these executive function deficits.

Conclusions:

• Serum glutamine may serve as a biomarker for illness severity in anorexia nervosa.
• Elevated serum glutamine is not directly associated with the observed impairments in executive function (set-shifting) in individuals with AN.