{
  "abstract": "Background Apathy, depression and anhedonia are clinically overlapping constructs, which hinders diagnostic clarity and treatment development. This study aimed to comprehensively characterise these syndromes to identify a core set of non-redundant symptoms that maximally dissociate them and to investigate the psychological nature of key distinguishing features.Methods Data from seven datasets (N=4578) of healthy individuals and patients with major depressive disorder were analysed using the Apathy Motivation Index, Beck Depression Inventory and Snaith-Hamilton Pleasure Scale. A machine-learning algorithm identified the most informative, non-redundant items for dissociating ‘pure’ apathy, depression and anhedonia. The nature of emotional apathy was further investigated with follow-up studies.Results Although substantial symptom overlap existed, ‘pure’ syndromes were present. Factor analysis revealed a robust five-factor structure, separating depression, anhedonia and three distinct apathy domains (behavioural, social and emotional). Machine learning identified 10 core symptoms that differentiated the pure syndromes with high accuracy (area under the curve >0.90) and could also identify well the presence of each syndrome in individuals suffering from two or more syndromes. Emotional apathy negatively correlated with depression and was specifically associated with reduced affective empathy and a diminished sensitivity to the intensity of negative facial emotions, rather than with alexithymia or antidepressant-induced emotional blunting.Conclusions Apathy, depression and anhedonia are dissociable constructs with distinct symptom signatures. Emotional apathy is a unique dimension which provides a novel target for research. A 10-item Apathy-Depression-Anhedonia Measure developed here provides a pragmatic tool for rapid, precise phenotyping to guide more personalised therapeutic strategies.",
  "authors": [
    {
      "affiliations": [
        "Department of Experimental Psychology, University of Oxford, Oxford, UK"
      ],
      "name": "Sijia Zhao"
    },
    {
      "affiliations": [
        "School of Mental Health and Psychological Sciences, Anhui Medical University, Hefei, Anhui, People's Republic of China",
        "Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, People's Republic of China",
        "Anhui Province Key Laboratory of Cognition and Neuropsychiatric Disorders, Hefei, People's Republic of China",
        "Collaborative Innovation Center of Neuropsychiatric Disorders and Mental Health, Hefei, People's Republic of China"
      ],
      "name": "Rong Ye"
    },
    {
      "affiliations": [
        "Division of Clinical Neurology, John Radcliffe Hospital, Oxford, UK"
      ],
      "name": "Aayushi Sen"
    },
    {
      "affiliations": [
        "Lyon Neuroscience Research Centre, Bron, France"
      ],
      "name": "Jacqueline Scholl"
    },
    {
      "affiliations": [
        "Centre for Developmental Sciences, School of Psychology, University of Birmingham, Birmingham, UK",
        "Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK",
        "Institute for Mental Health, School of Psychology, University of Birmingham, Birmingham, UK"
      ],
      "name": "Patricia Lockwood"
    },
    {
      "affiliations": [
        "Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK",
        "Institute for Mental Health, School of Psychology, University of Birmingham, Birmingham, UK"
      ],
      "name": "Meijia Li"
    },
    {
      "affiliations": [
        "Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK",
        "Institute for Mental Health, School of Psychology, University of Birmingham, Birmingham, UK"
      ],
      "name": "Kübra Fethiye Karataş"
    },
    {
      "affiliations": [
        "Social and Cognitive Computing Department, Institute of High Performance Computing, Agency for Science, Technology and Research (A*STAR), Singapore"
      ],
      "name": "Yuen-Siang Ang"
    },
    {
      "affiliations": [
        "Department of Neurology, University of California San Francisco, San Francisco, California, USA"
      ],
      "name": "Simon J Little"
    },
    {
      "affiliations": [
        "Department of Psychiatry, University of Oxford, Oxford, UK"
      ],
      "name": "Catherine J Harmer"
    },
    {
      "affiliations": [
        "Anhui Mental Health Center, Hefei, Anhui, People's Republic of China",
        "Affiliated Psychological Hospital of Anhui Medical University, Hefei, People's Republic of China"
      ],
      "name": "Kongliang He"
    },
    {
      "affiliations": [
        "Department of Psychology and Sleep Medicine, The Second Affiliated Hospital of Anhui Medical University, Hefei, People's Republic of China"
      ],
      "name": "Qianqian Li"
    },
    {
      "affiliations": [
        "School of Mental Health and Psychological Sciences, Anhui Medical University, Hefei, Anhui, People's Republic of China",
        "Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, People's Republic of China",
        "Anhui Province Key Laboratory of Cognition and Neuropsychiatric Disorders, Hefei, People's Republic of China",
        "Collaborative Innovation Center of Neuropsychiatric Disorders and Mental Health, Hefei, People's Republic of China",
        "Anhui Provincial Institute of Translational Medicine, Hefei, People's Republic of China"
      ],
      "name": "Kai Wang"
    },
    {
      "affiliations": [
        "Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK",
        "Institute for Mental Health, School of Psychology, University of Birmingham, Birmingham, UK"
      ],
      "name": "Matthew A J Apps"
    },
    {
      "affiliations": [
        "Department of Experimental Psychology, University of Oxford, Oxford, UK",
        "Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK"
      ],
      "name": "Sanjay Manohar"
    },
    {
      "affiliations": [
        "Department of Experimental Psychology, University of Oxford, Oxford, UK",
        "Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK"
      ],
      "name": "Masud Husain"
    }
  ],
  "title": "On the relationships between apathy, depression and anhedonia",
  "uid": "3ee8b799-e95d-5311-a8be-6c721541e02f"
}