The Malleability of Body Representation in Anorexia Nervosa: the Sixth Finger Illusion (SESTODITO_AN)

October 3, 2024 updated by: Istituto Auxologico Italiano

Body representation can be explored using behavioural tasks such as motor imagery tasks as well as body illusions.

In both cases, evidence from studies on healthy individuals as well as patients with lesions to the central nervous system show that body representation is not set in stone: how we imagine our bodies is a dynamic and continuously updated process, to reflect changes in our own body as well as the environment.

In anorexia nervosa the representation of the body is very different from that of healthy individuals: the representation is more malleable, and easier to manipulate, while at the same time being more detached from physical constraints. These features of body representation in anorexia nervosa might contribute to the persistence of symptoms and to relapses too. Body representation has clear implications for treatment of anorexia nervosa too.

The study aims at evaluating the presence of differences in the malleability of the body representation, explored through the illusion of the sixth finger, between a group of people with AN and a group of normal weight people, taking into account the biomechanical constraints that characterize the physical and mentally represented body.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The ability to imagine our body in our mind is called body representation. This ability is grounded in sensory and perceptual process and it is crucial to plan action, to interact with the environment and so on. Body representation can be explored using behavioural tasks such as motor imagery tasks as well as body illusions.

Evidence from healthy individuals shows that we depend on physical constraints when we imagine actions we can do with our body: we are faster and more accurate in imagining an action that we can really perform. This phenomenon is called "biomechanical constraints effect" and it is an index that our brain is performing motor imagery. When a lesion occurs to the spinal cord, for example, this effect is not present anymore, supporting the idea that what occurs in our brain is strongly dependent on what we can do in the real word. This dependency from the real word, however, does not mean that the representation of the body in the mind is an exact copy of the physical body. For example, findings from experiments using body illusions show that we have a distorted representation of our body, even in absence of any lesion. Overall, evidence from body illusions in healthy individuals shows that we tend to overestimate features when we imagine our body, width in particular compared to length and height.

In both cases, evidence from studies on healthy individuals as well as patients with lesions to the central nervous system show that body representation is not set in stone: how we imagine our bodies is a dynamic and continuously updated process, to reflect changes in our own body as well as the environment.

Recent studies suggest that body representation is quite different in conditions that affect the body even in absence of central nervous system or brain impairments, such as anorexia nervosa. In patients affected by anorexia nervosa, motor imagery does not occur, and patients treat their body like it is an object. Similarly, when subjected to illusions of ownership, patients with anorexia nervosa experience the illusion more strongly than healthy individuals.

In anorexia nervosa the representation of the body is very different from that of healthy individuals: the representation is more malleable, and easier to manipulate, while at the same time being more detached from physical constraints. These features of body representation in anorexia nervosa might contribute to the persistence of symptoms and to relapses too. Body representation has clear implications for treatment of anorexia nervosa too.

The study aims at evaluating the presence of differences in the malleability of the body representation, explored through the illusion of the sixth finger, between a group of people with AN and a group of normal weight people, taking into account the biomechanical constraints that characterize the physical and mentally represented body.

Study Type

Observational

Enrollment (Actual)

60

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Italy
      • Milan, Italy
        • istituto Auxologico italiano IRCSS

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Female Anorexia Nervosa patients and female healthy controls

Description

Inclusion Criteria:

  • female
  • 18-55 years
  • bmi ≤ 17.5 Kg/m2 for AN and BMI between 18.5 Kg/m2 e 25 Kg/m2 for healthy controls

Exclusion Criteria:

  • psychopathologies related to psychosis or brain injury lesions

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Anorexia Nervosa (AN)
People affected by AN (DSM5); female, age 18-55, BMI ≤ 17.5 Kg/m2
Behavioral: sixth finger illusion
Participants will undertake the sixth finger illusion that is a body illusion which elicits the presence of an extra numerary finger due to visuo-tactile stimulation.
Healthy controls (HC)
female, age 18-55, BMI between 18.5 Kg/m2 and 25 Kg/m2
Behavioral: sixth finger illusion
Participants will undertake the sixth finger illusion that is a body illusion which elicits the presence of an extra numerary finger due to visuo-tactile stimulation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Sixth finger illusion questionnaire
Time Frame: Through study completion, an average of 1 year
Participants are asked to answer to a 6 questions questionnaire based on a likert scale
Through study completion, an average of 1 year

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Istituto Auxologico Italiano

Collaborators

Catholic University of the Sacred Heart
Birkbeck, University of London
Heriot-Watt University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 1, 2023

Primary Completion (Actual)

April 30, 2024

Study Completion (Actual)

April 30, 2024

Study Registration Dates

First Submitted

February 28, 2024

First Submitted That Met QC Criteria

March 14, 2024

First Posted (Actual)

March 18, 2024

Study Record Updates

Last Update Posted (Actual)

October 8, 2024

Last Update Submitted That Met QC Criteria

October 3, 2024

Last Verified

October 1, 2024

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 03C304

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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