INHIBITION AND EXECUTIVE FUNCTIONING IN TRICHOTILLOMANIA A Comparison With an Obsessive-Compulsive Disorder Group and a Healthy Control Group Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften (Dr. rer. nat.) dem Fachbereich Psychologie der Philipps-Universität Marburg vorgelegt von Antje Bohne aus Gütersloh Marburg/Lahn 2003 1 Table of Contents List of Tables and Figures .............................................................................................................5 Acknowledgments.........................................................................................................................6 Zusammenfassung.........................................................................................................................7 Abstract .......................................................................................................................................15 1 General Introduction...............................................................................................................22 1.1 Trichotillomania: Clinical Picture, Etiology, and Treatment........................................22 1.2 Impulse-Control Disorder or Obsessive-Compulsive Spectrum Disorder? ..................25 1.3 Rationale for the Current Investigation.........................................................................27 2 General Methods.....................................................................................................................30 2.1 Participants....................................................................................................................30 2.2 Measures .......................................................................................................................31 2.3 Materials........................................................................................................................34 2.4 Procedures.....................................................................................................................34 3 Study 1: Motor Inhibition in Trichotillomania and Obsessive-Compulsive Disorder ...........37 3.1 Abstract .........................................................................................................................38 3.2 Introduction...................................................................................................................39 3.3 Methods.........................................................................................................................43 3.3.1 Participants........................................................................................................43 3.3.2 Measures............................................................................................................45 3.3.3 Procedure...........................................................................................................46 3.3.4 Statistics ............................................................................................................47 3.4 Results...........................................................................................................................48 2 3.4.1 Symptom Severity, Verbal Intellectual Abilities, and Attention Span..............48 3.4.2 Motor Inhibition ................................................................................................49 3.5 Discussion .....................................................................................................................52 4 Study 2: Cognitive Inhibition in Trichotillomania and Obsessive-Compulsive Disorder......62 4.1 Abstract .........................................................................................................................63 4.2 Introduction...................................................................................................................64 4.3 Methods.........................................................................................................................70 4.3.1 Participants........................................................................................................70 4.3.2 Measures............................................................................................................72 4.3.3 Procedure...........................................................................................................72 4.3.4 Statistics ............................................................................................................74 4.4 Results...........................................................................................................................74 4.4.1 Symptom Severity, Verbal Intellectual Abilities, and Attention Span..............74 4.4.2 Free Recall.........................................................................................................75 4.4.3 Recognition .......................................................................................................77 4.4.4 Emotionality Rating..........................................................................................79 4.5 Discussion .....................................................................................................................81 5 Study 3: Executive Functioning in Trichotillomania and Obsessive-Compulsive Disorder..93 5.1 Abstract .........................................................................................................................94 5.2 Introduction...................................................................................................................95 5.3 Methods.........................................................................................................................98 5.3.1 Participants........................................................................................................98 5.3.2 Measures..........................................................................................................100 5.3.3 Neuropsychological Test Battery ....................................................................101 5.3.4 Procedure.........................................................................................................103 3 5.3.5 Statistics ..........................................................................................................104 5.4 Results.........................................................................................................................104 5.4.1 Symptom Severity, Verbal Intellectual Abilities, and Attention Span............104 5.4.2 Visuospatial Ability and Memory ...................................................................105 5.4.3 Executive Functioning.....................................................................................106 5.4.4 Post Hoc Analyses in OCD .............................................................................108 5.5 Discussion ...................................................................................................................109 6 General Discussion...............................................................................................................119 6.1 Etiology and Maintenance of TTM.............................................................................120 6.2 Classification of TTM.................................................................................................122 6.3 Conclusions on Treatment ..........................................................................................124 6.4 Limitations ..................................................................................................................126 6.5 Concluding Remarks...................................................................................................126 7 References ............................................................................................................................128 8 Appendix ..............................................................................................................................146 8.1 Appendix A: Recruitment Information Used..............................................................147 8.2 Appendix B: The Massachusetts General Hospital Hairpulling Scale (MGH-HS) ....148 8.3 Appendix C: Test Sequences Used .............................................................................150 8.4 Appendix D: Instruction Used in the GoNogo Experiment........................................151 8.5 Appendix E: Word Lists Used in the Directed Forgetting Experiment ......................152 8.6 Appendix F: Instruction Used in the Directed Forgetting Experiment .......................153 9 Curriculum Vitae..................................................................................................................155 4 List of Tables and Figures Tables 2.1 Overview of the Potential Course of a Test Session ............................................................36 3.1 GoNogo Errors as a Function of Group and Error Type......................................................59 3.2 GoNogo Errors and Demographic Variables as a Function of Trichotillomania Subtype...60 4.1 Correct Free Recall of Words as a Function of Group, Instruction and Word Type............89 4.2 Correct Recognition of Words as a Function of Group, Instruction and Word Type ..........90 4.3 Emotionality Rating of Words as a Function of Group, Instruction and Word Type ..........91 5.1 Group Means and Standard Deviations in Visuospatial and Memory Tasks.....................116