Lecture 9 - Re-thinking neurodiversity

The Social Brain: Critical Perspectives on Science, Society and Neurodiversity

Richard Ramsey

Today


Part 1

  • Re-thinking neurodiversity


Part 2

  • Read articles and discuss



Overview

  • Systems (not syndromes)
  • Complex systems
  • Dimensional framewroks
    • HiTOP
    • RDoC

Systems (not syndromes)

Nosology

  • The branch of medical science dealing with the classification of diseases.

Systems (not syndromes)


(Fried, 2022)

Natural kinds


(Fried, 2022)

Natural kinds of disease unit?


(Fried, 2022)

Historical forces, not empirical evidence

  • E.g., depression DSM-5 criteria:

  • 1 of the first 2 symptoms

  • at least 5/9 symptoms

  • for at least 14 days

How were these thresholds determined?

(Fried, 2022)

Diagnostic literalism

  • We take diagnostic categories for more than they are, which impedes progress.

e.g., case-control studies for depression, for example, assume that depression is a neat category. Two groups: depressed vs. otherwise healthy (or at least, not depressed).

  • “what are genes for depression?”

  • “what are the risk factors for depression?”

(Fried, 2022)

Evidence does not support neat categories

  • Inter-rater reliability
  • Disagreement about construct definitons
  • Heterogeneity
  • Comorbidity of diagnostic categories
  • Transdiagnostic risk factors
  • Dimensions, not catgeories

(Fried, 2022)

Why have categories at all?


  • They can be of clinical use

  • Semantic efficiency

  • Public health and organisation of treatment…

(Fried, 2022)

Reductionism


  • Reduce things into their parts to understand the whole

  • This is very useful and helpful in many different settings e.g., a car engine.

  • But for complex systems, such as the stock market or weather patterns, reductionism doesn’t work as well.

(Fried, 2022)

Reductionism in mental health

  • Study depression using a DSM-5 category (which has limited validity) and only study that one category

  • And focus on one level of description (i.e., a biological level)

  • Primarily study one-to-one relations

(Fried, 2022)

Complex systems

A complex systems perspective

A complex systems perspective


A complex systems perspective


Lake conditions oxygen, sunlight, fish, pollution, etc.

Mood personality, caffeine, sleep, email, etc.

Mental disorders as complex systems

Interactions between:

  • biological, psychological, and social features…

e.g., risk and protective factors, moods, thoughts, behaviours, predispositions, social environments.

  • One-to-many or many-to-many relations

Emergence

Dimensional frameworks

Existing dimensional frameworks


  • RDoC (NIMH, USA) e.g., Insel et al., 2010, The American Journal of Psychiatry

  • HiTOP initiative (Worldwide consortium) e.g., Conway et al., 2019, Perspectives on Psychological Science

(Conway et al., 2019; Insel et al., 2010)

HiTOP


(Conway et al., 2019)

Dimensions (not categories)

  • Rather than mental health categories, we have something else…

Grounded in decades of research, an alternate framework has emerged that characterizes psychopathology using empirically derived dimensions that cut across the boundaries of traditional diagnoses.

  • Primary focus on evidence-based dimensions
  • Dimensions evolve over time (i.e., dimensions can change if sufficient evidence is gathered)

(Conway et al., 2019)

HiTOP Figure 1


(Conway et al., 2019)

HiTOP Figure 2

(Conway et al., 2019)

HiTOP Figure 3


(Conway et al., 2019)

HiTOP summary

Adopting a hierarchical and dimensional approach, makes it possible to:

  • Dissect brain structure and function quantitatviely and thus highlight features that ….
    • are common to many (or all) mental disorders
    • are specific to spectra or syndromes
    • underlie key transdiagnostic symptoms

(Conway et al., 2019)

Take a break

Part 2 - Read and discuss

Discussion material


References

Conway, C. C., Forbes, M. K., Forbush, K. T., Fried, E. I., Hallquist, M. N., Kotov, R., Mullins-Sweatt, S. N., Shackman, A. J., Skodol, A. E., South, S. C., Sunderland, M., Waszczuk, M. A., Zald, D. H., Afzali, M. H., Bornovalova, M. A., Carragher, N., Docherty, A. R., Jonas, K. G., Krueger, R. F., … Eaton, N. R. (2019). A Hierarchical Taxonomy of Psychopathology Can Transform Mental Health Research. Perspectives on Psychological Science, 14(3), 419–436. https://doi.org/10.1177/1745691618810696
Fried, E. I. (2022). Studying Mental Health Problems as Systems, Not Syndromes. Current Directions in Psychological Science, 09637214221114089. https://doi.org/10.1177/09637214221114089
Insel, T., Cuthbert, B., Garvey, M., Heinssen, R., Pine, D. S., Quinn, K., Sanislow, C., & Wang, P. (2010). Research Domain Criteria (RDoC): Toward a New Classification Framework for Research on Mental Disorders. American Journal of Psychiatry, 167(7), 748–751. https://doi.org/10.1176/appi.ajp.2010.09091379

Acknowledgements