Are Mental Disorders Brain Diseases, and What Does This Mean? A Clinical-Neuropsychological Perspective

Abstract

Neuroscientific research has substantially increased our knowledge about mental disorders in recent years. Along with these benefits, radical postulates have been articulated according to which understanding and treatment of mental disorders should generally be based on biological terms, such as neurons/brain areas, transmitters, genes etc. Proponents of such a ‘biological psychiatry' claim that mental disorders are analogous to neurological disorders and refer to neurology and neuropsychology to corroborate their claims. The present article argues that, from a clinical-neuropsychological perspective, ‘biological psychiatry' is based on a mechanistic, ‘cerebrocentric' framework of brain (dys-)function which has its roots in experimental neuroscience but runs up against narrow limits in clinical neurology and neuropsychology. In fact, understanding and treating neurological disorders generally demands a systems perspective including brain, organism and environment as intrinsically entangled. In this way, ‘biological' characterizes a ‘holistic', nonreductionist level of explanation, according to which the significance of particular mechanisms can only be estimated in the context of the organism (or person). This is evident in the common observation that local brain damage does not just lead to an isolated loss of function, but to multiple attempts of reorganization and readaptation; it initiates new developments. Furthermore, treating brain disorders necessarily includes aspects of individuality and subjectivity, a conclusion that contradicts the purely ‘objectivist', third-person stance put forward by some proponents of biological psychiatry. In sum, understanding and treating brain damage sequelae in the clinical neurosciences demands a biopsychosocial perspective, for both conceptual and historical reasons. The same may hold for psychiatry when adopting a brain-based view on mental disorders. In such a perspective, biological psychiatry seems an interesting project but falls short of its original claims.

To Overcome Psychiatric Patients’ Mind–Brain Dualism, Reifying the Mind Won’t Help

“…Reductionism does not seem to be a successful paradigm in psychiatry, with clinical researchers looking for a brain-based nosology since more than 170 years (24), when psychiatric disorders are not generally classified on the neuroscientific level, cannot be diagnosed on that level in individual cases, and a patient's treatment response cannot be assessed there alone. It has been discussed elsewhere that this can be partially explained by the limitations of present methodology (22,25) or the normativity of psychiatric disorders (26,27).…”

“…As Glannon described, Biological Psychiatry found neuroscientific patterns statistically correlated with such instances of MDD and many other disorders. But not a single one of the hundreds of disorders classified in the DSM can generally be described, let alone individually diagnosed, on the neuroscientific level alone (22,23). Reductionism does not seem to be a successful paradigm in psychiatry, with clinical researchers looking for a brain-based nosology since more than 170 years (24), when psychiatric disorders are not generally classified on the neuroscientific level, cannot be diagnosed on that level in individual cases, and a patient's treatment response cannot be assessed there alone.…”

How Realistic Are the Scientific Assumptions of the Neuroenhancement Debate? Assessing the Pharmacological Optimism and Neuroenhancement Prevalence Hypotheses

“…Similarly, a major aim of the fifth edition of the Diagnostic and Statistics Manual (DSM-5) of the American Psychiatric Association published in 2013 was the discovery of neuroscientific biomarkers that are reliable targets particularly in the brain or genome for diagnosis and treatment of psychiatric disorders ( Kupfer et al, 2002 ; Hyman, 2007 ). In spite of these efforts and an unprecedented increase in scientific publications and knowledge, the high expectations in terms of translations to clinical applications were not met yet ( Schleim and Roiser, 2009 ; Schleim, 2014a ; Frisch, 2016 ). The failure to discover even a single reliable biomarker for any of the hundreds of DSM-5 classifications lead to the introduction of a new research paradigm, the Research Domain Criteria (RDoC), whose scientific superiority remains unclear at the present moment ( Kirmayer and Crafa, 2014 ).…”

Subjective Experience, Heterophenomenology, or Neuroimaging? A Perspective on the Meaning and Application of Mental Disorder Terms, in Particular Major Depressive Disorder

“…The many challenges of defining mental disorder constructs have been discussed elsewhere ( Kendler et al, 2011 ; Frances, 2013 ; Stier, 2013 ; Frisch, 2016 ). Given the normative, institutional, and even financial interests involved ( Barbui, 2015 ), it is understandable that many psychiatrists hoped that genetic and neuroimaging research might yield biomarkers ( Figure 1 ).…”

“…However, already the conceptual complexity of MDD that we just addressed makes it theoretically very unlikely to find biomarkers which reliably co-occur with instantiations of that condition. And this is indeed the empirical situation for all mental disorders so far: Out of the 150–600 disorders of the DSM-5, depending on how one counts, and in spite of great research efforts of the last decades, not a single one can be diagnosed reliably with a biomarker ( American Psychiatric Association [APA], 2013 ; Frisch, 2016 ). There remains of course a theoretical possibility that research methods of the future or a breakthrough in data analysis will change that situation ( Schleim, 2015 ).…”