Table 3 Studies characteristics
Study | Sensory modalities involved | Paradigms and measures | Main outcomes | Main outcomes interpretation | Sample features (diagnosis, subtype, size, mean age, mean BMI, mean illness duration, and relative SD/ SE) | Gender |
|---|---|---|---|---|---|---|
Provenzano et al. (2021) | Visual–Tactile–Proprioceptive | Full Body Illusion in Virtual Reality from egocentric (1st person) perspective) Embodiment measures: Embodiment questionnaire (see [50]), skin temperature Emotional Valence: Visual Analogue Scale Avatar Selection Task in Virtual Reality from allocentric (3rd person) perspective | Full Body Illusion in Virtual reality Embodiment measures No significant differences between groups in embodiment measures Emotional Valence Patients with AN experienced more negative emotions after being exposed to the avatar with a greater BMI as compared to the avatar with a lower BMI. The opposite pattern was instead found in the control group Avatar Selection Task in Virtual Reality Individuals with AN and HCs differed in body dissatisfaction, with patients reporting overall higher levels of body dissatisfaction and a desire to have a thinner body No differences were observed between groups in the real body estimation task; however, participants in both groups tended to overestimate their body dimensions | Individuals with Anorexia Nervosa might present alterations in the affective and emotional components of body experience, rather than in the perceptual one | AN (Subtype restrictive) = 20; age (years) = 23.30 ± 7.61 years; BMI (kg/m2) = 15.87 ± 1.12; illness duration NR; diagnostic criteria DSM-5 HCs = 20; age (years) 23.85 ± 3.23; BMI (kg/m2) = 18.98 ± 1.01 | F |
Case et al. (2012) | Visual-Haptic-Proprioceptive Integration | Size Weight Illusion [51] | Patients with AN experienced the illusion (and the reversed size weight illusion) significantly less than controls. This is despite normal weight discrimination ability | Individuals with AN seem to present abnormal visual-haptic-proprioceptive sensory integration abilities which might explain the reason why the visual perception of the body in a mirror does not correct the patient's distorted body representation image | AN (Subtype NR) = 10; age (years) = 29.1 ± 11.0 years; BMI (kg/m2) = 17.1 ± 0.9; illness duration (months) = 36 (SD NR); diagnostic criteria DSM-IV-TR HCs = 10; mean age 25.8 ± 9.0 years; mean BMI 21.7 ± 1.6 kg/m2 | F |
Zopf et al. (2016) | Visual—Tactile—Proprioceptive | Rubber Hand Illusion from egocentric (1st person) perspective [30] Embodiment measures: Embodiment questionnaire [30, 32] Body perception measures: Reaching task [52] | Rubber Hand Illusion and Embodiment Questionnaire Patients with AN reported significantly higher embodiment scores than controls in synchronous conditions Body perception measures Differences in reaching trajectories were found between the groups; specifically, individuals with AN made more reach-to-grasp endpoint errors toward external visual information compared to controls | Individuals affected by AN show deficits in processing visual-proprioceptive signals compared to controls. Thus, the results seem to support the idea that multisensory perception of body position is abnormal in individuals with AN | AN (Subtype NR) = 23; age (years) = 21.87, SD = 2.79; BMI (kg/m2) = 15.82, SD = 1.27; illness duration (years) = 5.26, SD = 3.60; diagnostic criteria DSM-IV HCs = 23; age (years) = 21.48, SD = 2.35; BMI (kg/m2) = 21.16, SD = 2.10 | F |
Guardia et al. (2013) | Visual–Haptic–Proprioceptive–Vestibular | Spatial orientation constancy and body orientation perception: Subjective Vertical Task and body Z– axis perception[53] | Subjective Vertical Task Patients with AN showed a higher A-effect—meaning a deviation of the tactile and visual subjective verticality towards the body under tilted conditions Body Z-axis No differences emerged between groups concerning tactile and visual body Z-axis judgments in the upright position; differences instead emerged when tilting the body, where individuals with AN judged the body as more tilted compared to controls | Participants with AN seem to present multisensory deficits in spatial orientation which can relate to a decrease in somatosensory information processing; such difference could be explained in terms of | AN (Subtype restrictive) = 25; age (years) = 22.24, SD = 8.59 years; BMI (kg/m2) = 14.89, SD = 1.10; illness duration (years) = 4.57, SD = 6.52; diagnostic criteria DSM- IV-TR HCs = 25; age (years) = 22.88, SD = 3.63; BMI (kg/m2) = 21.65, SD = 1.72 | F |
Risso et al. (2020) | Visual-Tactile | Multisensory Processing Assessment task [54] | Individuals with AN tended to overestimate the width of the ellipse more than HCs in the tactile modality, whereas no differences were observed in the visual condition Participants with AN showed a higher visual and tactile discrimination threshold compared to controls Individuals with AN accurately integrated tactile and visual information as HCs; however, differences emerged in terms of discrimination thresholds: the clinical group showed a lower bimodal threshold as compared to unimodal conditions whereas HCs showed similar thresholds across conditions | Patients with AN might have difficulties in visual and tactile sensory processing instead of deficits in multisensory integration | AN (Subtype restrictive) = 19; age (years) = 26.12, SD = 9.34; BMI (kg/m2) = 15.15, SD = 2.64; illness duration NR; diagnostic criteria DSM-5 BCHC = 9; age (years) = 25.67, SD = 2.18; BMI (kg/m2) = 20.49, SD = 1.43 HCs = 19; age (years) = 24.47, SD = 1.26; BMI (kg/m2) = 19.86, SD = 1.94 | F |
Beckmann et al. (2020) | Visual-Proprioceptive- Vestibular | Aperture task from egocentric (1st person) perspective [49] | Patients with AN reported a higher critical aperture/ shoulder ratio than HCs, meaning that patients rotate their shoulders for relatively larger door widths compared to controls | Individuals with AN tend to rely on an incoherent body schema to plan and perform actions; specifically, they tend to unconsciously estimate their body size to be larger than in reality | AN (Subtype restrictive) = 18; AN (Subtype binge/purge) = 5; age (years) = 24.67, SD = 5.61; BMI (kg/m2) = 14.60, SD = 1.88; illness duration (years) = 5.81 SD = 4.83; diagnostic criteria ICD-10 HCs = 21; age (years) = 24.19, SD = 3.12; BMI (kg/m2) = 21.95, SD = 1.30 | F |
Chirico et al. (2019) | Auditory-visual | Sound-Induced Flash Illusion [55] | Patients with AN were less accurate compared to HCs for each SOA and sensory modality No significant differences were observed between groups in the visual condition for SOA from 70 to 110 ms; however, individuals with AN showed difficulties in visual trials with longer SOAs (i.e.,150 ms, 230 ms) Participants with AN were never able to detect the double sound in the auditory condition In the visual condition, the clinical group reported a higher number of correct responses compared to the other two modalities; difficulties emerged for longer visual SOA, as well as for the bimodal condition across all SOA | AN showed an impaired ability to integrate auditory and visual stimuli | AN (Sybtype NR) = 9; age (years) = 30, SD = 10.46; BMI (kg/m2) = 15.59, SD = 1.96; illness duration NR; diagnostic criteria DSM-5 HCs = 9; age (years) = 24.56, SD = 1.67; BMI (kg/m2) = 22.69, SD = 2.14 | F |
Eshkevcari et al. (2012) | Visual—Tactile—Proprioceptive | Rubber Hand Illusion from egocentric (1st person) perspective Embodiment measures: Embodiment Questionnaire, Proprioceptive drift Finger localization task | Embodiment Questionnaire Clinical groups composed of patients with AN and BN reported higher levels of embodiment than HCs However, these differences were not significant when controlling for mood Proprioceptive drift Patients with AN showed higher proprioceptive drift compared to HCs, whereas participants with BN did not differ from controls Finger localization task Individuals with AN showed more biased finger location estimation compared to controls, whereas patients with BN did not differ from HCs | People with eating disorders show a plastic bodily self compared to healthy controls. This malleability may stem from alterations and deficits in processing body-related information | AN (Sybtype restrictive) = 24; AN (Subtype binge/purge) = 12; age (years) = 23, SD = 18; BMI (kg/m2) = 16.1, SD = 2.71; illness duration (years) = 6, SD = 11; diagnostic criteria DSM-IV-TR BN = 22; age (years) = 22.5, SD = 10; BMI (kg/m2) = 20.9, SD = 4.28; illness duration (years) = 7, SD = 4; diagnostic criteria DSM-IV-TR ENDOS = 20; age (years) = 27.5, SD = 16; BMI (kg/m2) = 19.7, SD = 5.54; illness duration (years) = 11.5, SD = 12; diagnostic criteria DSM-IV-TR HCs = 61; age (years) = 24.7, SD = 7; BMI (kg/m2) = 21.5, SD = 2.80 | F |
Keizer et al. 2016 | Visual–Tactile–Proprioceptive | Full Body Illusion in Virtual Reality from egocentric (1st person) perspective Embodiment measures: Embodiment Questionnaire Body Size Estimation Task | Embodiment Questionnaire No significant differences were observed between groups concerning illusion strength as reflected by Embodiment Questionnaire Body Size Estimation Task Patients with AN tended to misestimate their body width and circumferences more than controls | Participants with AN may base their body size on the most recent visual information available to them. The tendency of people with AN to overestimate their body size is not the result of a general bias to perceive their own body as larger than reality, but it is specifically limited to perceiving the body as wider and rounder | AN (Subtype NR) = 30; age (years) = 22.03, SD = 3.67; BMI (kg/m2) = 18.11, SD = 1.68; illness duration (months) = 110.61, SD = 11.62; diagnostic criteria DSM-IV HCs = 29; age (years) = 21.07, SD = 2.34; BMI (kg/m2) = 20.77, SD = 1.48 | F |
Keizer et al. 2019 | Visual-Proprioceptive- Vestibular | Hoop Task from egocentric (1st person) perspective | At the baseline, participants affected by AN tended to misestimate the smallest hoop that would allow them to fit through compared to controls | Patients with AN seem to present a suboptimal ability to derive body size estimates from multisensory information processing of bodily information | AN (subtype NR) = 12; age (years) = 23.17, SD = 5.67; BMI (kg/m2) = 20.11, SD = 1.17; illness duration (months) = 12.29, SD = 10.32; diagnostic criteria DSM-5 AN (subtype NR) = 14; age (years) = 22.87, SD = 2.90; BMI (kg/m2) = 19.53, SD = 1.04; illness duration (months) = 7, SD = 3.93; diagnostic criteria DSM-5 HCs = 20 age (years) = 21.21, SD = 1.44; BMI (kg/m2) = 20.80, SD = 1.61 | F |
Metral et al. 2014 | Visual-Proprioceptive- Vestibular | Aperture Task from egocentric (1st person) perspective asking both to image and pass through doorway-like apertures | Individuals with AN showed a higher passability ratio (i.e. the ratio between the critical aperture size and shoulder width) relative to HCs, both in motor imagery and real action aperture tasks | Patients with AN show body schema alterations that influence action planning. Moreover, such alteration seems to resist corrections stemming from sensorimotor information generated when performing motor tasks. These results suggest that the central nervous system in individuals affected by this condition might be locked to a false representation of the body that cannot be updated | AN (2 subtype binge/purge, 12 rescriting) = 14 age (years) = 24.14, SD = 0.65; BMI (kg/m2) = 14.70, SD = 1.50; illness duration (years) = 5.71, SD = 9.67; diagnostic criteria DSM-IV-R HCs = 14; age (years) = 25.21, SD = 7.77; BMI (kg/m2) = 21.62, SD = 1.82 | F |
Guardia et al. 2010 | Visual- Proprioceptive- Vestibular | Aperture Task from egocentric (1st person) perspective | The group composed of individuals with AN showed an abnormally higher critical aperture size to shoulder width ratio compared to controls. Additionally, this misestimation correlated with the duration of illness and the degree of body concerns | Body size overestimation consistently observed in individuals with AN might not merely be due to psychological and affective factors; specifically perceptual processing of the body at a neural level might be impaired (i.e., alterations at the level of the parietal network) | AN (subtype NR) = 25; age (years) = 24.32, SD = 6.54 BMI (kg/m2) = 15.14, SD = 1.55; illness duration (years) = 5.3, SD = 4.8; diagnostic crtieria DSM IV HCs = 25; age (years) = 23.04, SD = 5.98; BMI (kg/m2) = 21, SD = 1.99 | F |
Guardia et al. 2012 | Visual-Proprioceptive- Vestibular | Aperture Task from both egocentric (1st person) and allocentric (3rd person) perspectives | Individuals with AN showed a higher passability ratio compared to HCs when the task was proposed from egocentric but not from allocentric spatial reference frame | The body overestimation and the alteration in body schema reliably observed in individuals with AN might reflect a deeper deficit in the crossmodal integration ability of bodily information | AN (12 subtype restricting, 13 binge/purge subtype = 25; age (years) = 28.84, SD = 7.75; BMI (kg/m2) = 15.65, SD = 1.24; illness duration NR; diagnostic criteria DSM-IV-R HCs = 25; age (years) = 24.48, SD = 6.7; BMI (kg/m2) = 22.06, SD = 2.37 | F |