Background: Food avoidance is critically important in the psychopathology of anorexia nervosa, and very relevant to the maintenance of calorie restriction. Many past studies have examined this process, and two main mechanisms are thought to be responsible for it: automatic, habitual responses and elevated inhibitory control abilities. Past studies used many different methods to examine these mechanisms, the most relevant being the “approach-avoidance task” and “stop signal task”. Thanks to technological advancement, the techniques used to perform these studies are becoming more and more advanced; one of the most recent ones is virtual reality. The previous virtual reality, go and stop-trial motion tracking study examined the approach to food and neutral stimuli, in AN-R patients and healthy controls. The analysis detected an avoidance bias toward food in AN-R patients, together with an increased generalized inhibitory control. Study aim: This study aims to better understand the mechanisms supporting calorie restriction in AN-R, trough a virtual reality motion tracking experiment. The objectives are: (1) replicate the finding of the previous study and detect and avoidance bias toward food in AN-R patients; (2) examine the differences in the approach between high-calorie and low-calorie food; (3) probe the effects of amodal / semantic stimuli. For this purpose, two new types of stimuli were introduced, relatively to the previous study: low-calorie food and amodal stimuli. Methods: The virtual reality go-trial and stop-trial data, toward high-calorie, low-calorie, neutral and amodal stimuli were collected from a sample of 50 subjects. To investigate the hypothesis, four specific contrasts of interest were defined: high calorie vs. neutral, high-calorie vs. low-calorie, amodal vs. neutral, amodal vs. high-calorie. The main dependent-variable was the maximum depth position in stop-trials, and some secondary recorded variables were: maximum speed in go-trials, maximum acceleration in go-trials, time-to-stop in stop-trials, breaking distance in stop-trials. Results: All four of the contrasts of interest showed an effect of group regarding the maximum depth position: patients had a shorter approach toward any kind of stimuli, relatively to controls. The amodal vs. high-calorie and the amodal vs. neutral contrasts showed an additional effect of the stimulus type: maximum depth position was bigger toward amodal stimuli, both in patients and controls. The analysis of the secondary variables only showed a significant finding regarding the maximum speed in go-trials between amodal and high calorie stimuli. The collected data does not reinforce the hypothesis of a food-avoidance bias in AN-R patients, it does not show any differences in the approach between high-calorie and low-calorie food, and it speculates that amodal stimuli aren’t comparable to high-calorie stimuli, and neither to neutral stimuli. The shorter maximum depth positions, toward any kind of stimuli, detected in patients supports the hypothesis of the calorie restriction being a result of and elevated inhibitory control ability in AN-R. Conclusions: The heterogeneity of the studies examining the mechanisms sustaining calorie restriction in AN makes it difficult to make any clear statements about the psychopathology of this disease. However, the development of new, more accurate, investigation methods can be very helpful to expand our current understanding of AN. The implementation and improvement of virtual reality techniques has a good potential in the comprehension of AN psychopathology and its therapy.
Presupposti dello studio: L’evitamento del cibo è centrale nella psicopatologia e mantenimento della restrizione calorica nell’anoressia nervosa. Diversi studi in letteratura hanno analizzato questo processo, attribuendolo a due possibili meccanismi: evitamento automatico abitudinario e aumentata capacità di controllo inibitorio. A questo scopo, in passato sono state utilizzate metodiche molto eterogenee, tra le più rilevanti: approach-avoidance task e stop-signal task. Grazie all’evoluzione in campo tecnologico, sono disponibili metodiche sempre più avanzate per lo svolgimento di questi studi; uno dei metodi implementati più recentemente è la realtà virtuale. Un precedente studio di motion tracking in realtà virtuale aveva esaminato l’approccio a stimoli di cibo e stimoli neutri in pazienti affette da AN-R e controlli sani, rilevando la presenza di un bias di evitamento nei confronti del cibo, abbinato ad un aumentato controllo inibitorio generalizzato nelle pazienti. Scopo dello studio: Il seguente studio mira a investigare il meccanismo alla base della restrizione calorica nell’AN-R, tramite un esperimento di motion tracking in realtà virtuale. Gli scopi dello studio sono: (1) riprodurre il dato del precedente studio di motion tracking, cioè il bias di evitamento verso il cibo nelle pazienti; (2) indagare le differenze nell’approccio tra cibo a basso e alto contenuto calorico; (3) esplorare l’effetto degli stimoli semantici. A questo scopo vengono quindi introdotti due nuovi tipi di stimolo rispetto al precedente studio in realtà virtuale: cibo a basso contenuto calorico e stimoli semantici. Metodi: Sono stati raccolti i dati di 50 partecipanti, che hanno svolto un compito in realtà virtuale composto da go-trial e stop-trial verso quattro tipi di stimolo: cibo ad alto contenuto calorico, basso contenuto calorico, oggetti neutri e stimoli semantici. Per indagare le ipotesi dello studio sono stati definiti quattro specifici contrasti: alto contenuto calorico vs. oggetti neutri, alto contenuto calorico vs. basso contenuto calorico, semantico vs. oggetti neutri, alto contenuto calorico vs oggetti neutri. La maximum depth position negli stop-trial è stata considerata la variabile dipendente principale dello studio e come variabili secondarie sono state indagate: la velocità massima nei go-trial, l’accelerazione massima nei go-trial, il tempo necessario all’interruzione del movimento negli stop-trial, la distanza percorsa dal segnale di stop all’interruzione del movimento negli stop-trial. Risultati: In tutti e quattro i contrasti che analizzavano la maximum depth position, è emerso un effetto del fattore gruppo: le pazienti hanno una maximum depth position minore dei controlli verso ogni stimolo. Nei confronti tra stimolo semantici e cibo ad alto contenuto calorico/oggetti neutri è emerso anche un effetto del fattore stimolo: la maximum depth position verso gli stimoli semantici è maggiore che verso il cibo e gli oggetti neutri, sia nelle pazienti che nei controlli. Nell’analisi delle variabili secondarie l’unico dato statisticamente significativo è il rilevamento di un effetto del fattore gruppo nella velocità dei go-trial tra stimoli semantici e ad alto contenuto calorico. Quindi, dai risultati raccolti non si conferma la presenza di un bias di evitamento verso il cibo nelle pazienti con AN-R, non si rileva alcuna differenza significativa nell’approccio tra cibo ad alto e basso contenuto calorico, e si ipotizza che gli stimoli semantici non siano equiparabili né a stimoli di cibo né ad oggetti neutri. La maximum depth position minore nelle pazienti, per ogni tipo di stimolo, è un dato a supporto dell’ipotesi che la restrizione calorica nell’AN-R sia caratterizzata da un maggiore controllo inibitorio generalizzato. Conclusioni: L’eterogeneità degli studi che indagano i meccanismi alla base della restrizione calorica nell’anoressia nervosa
risposta inibitoria nei confronti di stimoli di cibo a diverso contenuto calorico nell'anoressia nervosa: uno studio di motion tracking in realtà virtuale
BETTIO, CHIARA
2023/2024
Abstract
Background: Food avoidance is critically important in the psychopathology of anorexia nervosa, and very relevant to the maintenance of calorie restriction. Many past studies have examined this process, and two main mechanisms are thought to be responsible for it: automatic, habitual responses and elevated inhibitory control abilities. Past studies used many different methods to examine these mechanisms, the most relevant being the “approach-avoidance task” and “stop signal task”. Thanks to technological advancement, the techniques used to perform these studies are becoming more and more advanced; one of the most recent ones is virtual reality. The previous virtual reality, go and stop-trial motion tracking study examined the approach to food and neutral stimuli, in AN-R patients and healthy controls. The analysis detected an avoidance bias toward food in AN-R patients, together with an increased generalized inhibitory control. Study aim: This study aims to better understand the mechanisms supporting calorie restriction in AN-R, trough a virtual reality motion tracking experiment. The objectives are: (1) replicate the finding of the previous study and detect and avoidance bias toward food in AN-R patients; (2) examine the differences in the approach between high-calorie and low-calorie food; (3) probe the effects of amodal / semantic stimuli. For this purpose, two new types of stimuli were introduced, relatively to the previous study: low-calorie food and amodal stimuli. Methods: The virtual reality go-trial and stop-trial data, toward high-calorie, low-calorie, neutral and amodal stimuli were collected from a sample of 50 subjects. To investigate the hypothesis, four specific contrasts of interest were defined: high calorie vs. neutral, high-calorie vs. low-calorie, amodal vs. neutral, amodal vs. high-calorie. The main dependent-variable was the maximum depth position in stop-trials, and some secondary recorded variables were: maximum speed in go-trials, maximum acceleration in go-trials, time-to-stop in stop-trials, breaking distance in stop-trials. Results: All four of the contrasts of interest showed an effect of group regarding the maximum depth position: patients had a shorter approach toward any kind of stimuli, relatively to controls. The amodal vs. high-calorie and the amodal vs. neutral contrasts showed an additional effect of the stimulus type: maximum depth position was bigger toward amodal stimuli, both in patients and controls. The analysis of the secondary variables only showed a significant finding regarding the maximum speed in go-trials between amodal and high calorie stimuli. The collected data does not reinforce the hypothesis of a food-avoidance bias in AN-R patients, it does not show any differences in the approach between high-calorie and low-calorie food, and it speculates that amodal stimuli aren’t comparable to high-calorie stimuli, and neither to neutral stimuli. The shorter maximum depth positions, toward any kind of stimuli, detected in patients supports the hypothesis of the calorie restriction being a result of and elevated inhibitory control ability in AN-R. Conclusions: The heterogeneity of the studies examining the mechanisms sustaining calorie restriction in AN makes it difficult to make any clear statements about the psychopathology of this disease. However, the development of new, more accurate, investigation methods can be very helpful to expand our current understanding of AN. The implementation and improvement of virtual reality techniques has a good potential in the comprehension of AN psychopathology and its therapy.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/67026