Julie Refardt

Objective Distinguishing arginine vasopressin deficiency (AVP-D; central diabetes insipidus) from primary polydipsia (PP), commonly referred to as psychogenic polydipsia, is challenging. Psychopathologic findings, commonly used for PP diagnosis in clinical practice, are rarely evaluated in AVP-D patients, and no comparative data between the two conditions currently exist. Design Data from two studies involving 82 participants (39 AVP-D, 28 PP, and 15 healthy controls [HC]). Methods Psychological evaluations were conducted using standardized questionnaires measuring anxiety (State-Trait Anxiety-Inventory [STAI]), alexithymia (Toronto Alexithymia-Scale [TAS]), depressive symptoms (Beck’s Depression Inventory-II [BDI-II], and overall mental health (Short-Form-36 Health-Survey [SF-36]). Higher STAI, TAS, and BDI-II scores suggest elevated anxiety, alexithymia, and depression, while higher SF-36 scores signify better overall mental health. Results Compared to HC, patients with AVP-D and PP showed higher levels of anxiety (HC 28 points [24-31] vs AVP-D 36 points [31-45]; vs PP 38 points [33-46], p<0.01), alexithymia (HC 30 points [29-37] vs AVP-D 43 points [35-54]; vs PP 46 points [37-55], p<0.01), and depression (HC 1 point [0-2] vs AVP-D 7 points [4-14]; vs PP 7 points [3-13], p<0.01). Levels of anxiety, alexithymia, and depression showed no difference between both patient groups (p=0.58, p=0.90, p=0.50, respectively). Compared to HC, patients with AVP-D and PP reported similarly reduced self-reported overall mental health scores (HC 84 [68-88] vs AVP-D 60 [52-80], p=0.05; vs PP 60 [47-74], p<0.01). Conclusion This study reveals heightened anxiety, alexithymia, depression, and diminished overall mental health in patients with AVP-D and PP. The results emphasize the need for careful interpretation of psychopathological characteristics to differentiate between AVP-D and PP.