Anterior limb of internal capsule stimulation in obsessive-compulsive disorder
: how it affects decision-making under risk and ambiguity

  • Maria Silva Graça Monteiro (Student)

Student thesis: Master's Thesis


Purpose: Decision-making processes are a basis of human condition, every day we areconfronted with situations where we have to make a decision, and sometimes, theoutcomes of these situations are unpredictable and involve some risk. Unbalances in thedecision-making process may lead to psychiatric disorders. It is known that a mainsymptom of obsessive-compulsive disorder (OCD) is the presence of doubt, and therefore,an aversion to risky behaviors and situations; some authors even consider OCD as adisorder of decision-making. This study aims to understand the impact the chronicstimulation of the anterior limb of the internal capsule (ALIC) on the decision-makingprofile towards ambiguity and risk of OCD patients.Participants and method: Three OCD patients with DBS were matched with OCD onlypatients and healthy controls. Two behavioral tasks, the Risky Choice or Sure Amount ofMoney and the Iowa Gambling Task were performed in the ON and OFF condition bythe DBS patients. The patients performed the Raven’s Progressive Matrices and answeredto the Everyday Risk Inventory on the washout period. Before the first and second timethat the DBS subjects performed the behavioral tasks, the Subjective Units of DisturbanceScale was applied. OCD and healthy controls also repeated the behavioral task. Allsubjects also completed the Yale-Brown Obsessive-Compulsive Scale.Results: DBS subjects showed a lesser risk averse profile towards ambiguity when theDBS was ON (IGTON < IGTOFF). Also, patients with DBS had a lesser risk averseprofile towards risk, than their matched OCD controls (RCSAMDBS > RCSAMOCD).Lastly, DBS treated patients show the same decision-making profile towards risky thantheir matched healthy controls (RCSAMDBS = RCSAMDBS).Conclusion: The stimulation of the ALIC, in OCD patients, makes them less aversetowards ambiguity. Also, the stimulation of this target makes patients less averse to risk,when compared with obsessive-compulsive patients. Finally, DBS patients seem to ableto take the same risk than their matched healthy controls.
Date of Award20 Jul 2020
Original languageEnglish
Awarding Institution
  • Universidade Católica Portuguesa
SupervisorFilipa Ribeiro (Supervisor) & Frederico Simões do Couto (Co-Supervisor)


  • Decision making towards risk
  • Decision-making towards ambiguity
  • Obsessive-compulsive disorder
  • Deep brain stimulation


  • Mestrado em Neuropsicologia

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