Academic textbooks on ADHD genetics: balanced or biased?

Figures & data

Table I. Criteria for classifying ES in textbooks.

		Molecular genetic studies
		Omitted: No involved genes mentioned, or only involved genes mentioned, but no ES specified, verbally or numerically	Mentioned: ES mentioned verbally and/or numerically
Quantitative genetic studies	Omitted: No ES mentioned verbally or numerically	(A) Superficial: no reference to explained variance of individual or aggregated genes, and no estimate of heritability of family/twin or adoption studies.	(B) Molecular genetics only: reference to explained variance of individual or aggregated genes, but not to heritability according to family/twin or adoption studies.
	Mentioned: ES as range (60–90), exact number (0.76), or verbally qualified (high/low, etc.)	(C) Quantitative studies only: reference to heritability according to family/twin or adoption studies, but no reference to explained variance of individual or aggregated genes.	(D) Elaborate: reference to explained variance of individual or aggregated genes, and reference to heritability according to family/twin or adoption studies.

Table II. Specificity of ES (quantitative/molecular genetics) in textbooks.

		Molecular genetics studies
		Omitted: No involved genes mentioned, or only involved genes mentioned, but no ES specified, verbally or numerically	Mentioned: ES mentioned verbally and/or numerically
Twin studies	Omitted: No ES mentioned verbally or numerically	A: superficial	B: molecular genetics only
		n = 10 (23%)^a	n = 3 (7%)
		Average: 5 pages^b	Average: 15 pages
		Specific genes: n = 1^C	Specific genes: n = 2
		(10% of category)	(100% of category)
	Mentioned: ES as range (60–90), exact number (0.76), or verbally qualified (high/low, etc.)	C: quantitative studies only	D: elaborate
		n = 20 (47%)	n = 10 (23%)
		Average: 7 pages	Average: 16 pages
		Specific genes: n = 8	Specific genes n = 10
		(38% of category)	(100% of category)
			Contrast: n = 9^d

^aPercentage of total.

^bAverage number of pages of books in category.

^cSpecific gene(s) mentioned by authors (by name, e.g., DRD4) or by function (e.g., dopamine related).

^dContrast between ES of quantitative vs. molecular genetic studies explicated.

Table A1. Textbooks and their mentioning of ES.

Superficial books (n = 10)	Anderson, V., Northam, E., Hendy, J., & Wrennall, J. (2001). Developmental neuropsychology: A clinical approach (1st ed.). Philadelphia, PA: Taylor & Francis. Belsky, J. (2013). Experiencing the lifespan (3rd ed.). New York, NY: Worth Publishers.
	Bernstein, D., Penner, L.A., Clarke-Stewart, A., & Roy, E. (2012). Psychology (9th international ed.). Boston, MA: Cengage Learning.
	Comer, R. J. (2013). Fundamentals of abnormal psychology (7th ed.). New York, NY: Worth Publishers.
	Farrell, M. (2012). Educating special children: An introduction to provision for pupils with disabilities and disorders (2nd ed.). New York, NY: Routledge.
	Gray, P., & Bjorklund, D. F. (2014). Psychology (7th ed.). New York, NY: Worth Publishers.
	Kolb, B., & Whishaw, I. Q. (2015). Fundamentals of human neuropsychology (7th ed.). New York, NY: Worth Publishers.
	Ruijssenaars, A. J. J. M., & Ghesquière, P. (1999). Neuropsychologische aspecten van problemen op school (1st ed.). Belgium: Acco, Leuven.
	Tak, J. A., Bosch, J. D., Begeer, S., & Albrecht, G. (2014). Handboek psychodiagnostiek voor de hulpverlening aan kinderen (8th ed.). Utrecht: De Tijdstroom.
	Van der Wolf, K., & Van Beukering, T. (2009). Gedragsproblemen in scholen: Het denken en handelen van leraren (1st ed.). Leuven: Acco.
Molecular genetics only (n = 3)	Barlow, D., & Durand, V. (2015). Abnormal psychology: An integrative approach (7th ed.). Stamford, CT: Cengage Learning.
	Durand, V., & Barlow, D. (2013). Essentials of abnormal psychology (6th ed.). Stamford, CT: Cengage Learning.
	Stahl, S. M. (2013). Stahl’s essential psychopharmacology: Neuroscientific basis and practical applications (4th ed.). New York, NY: Cambridge University Press.
TF studies only (n = 20)	Bear, M. F., Connors, B. W., & Paradiso, M. A. (2016). Neuroscience: Exploring the brain (4th ed.). Baltimore, MD: Lippincott Williams & Wilkins.
	Berk, L. E. (2013). Child development (9th international ed.). New Jersey, NJ: Pearson Education.
	Braet, C., & Bögels, S. M. (2014). Protocollaire behandelingen voor kinderen en adolescenten met psychische klachten (2nd ed.). Amsterdam: Uitgeverij Boom.
	Bukatko, D., & Daehler, M. W. (2012). Child development: A thematic approach (6th international ed.). Belmont, CA: Wadsworth.
	Carter, R. (2014). The brain book (2nd ed.). London: Dorling Kindersley.
	Delfos, M. F. (2009). Ontwikkelingspsychopathologie (7th ed.). Amsterdam: Pearson.
	Gazzaniga, M., Heatherton, T., & Halpern, D. (2016). Psychological Science (5th international student ed.). New York, NY: W. W. Norton, Inc.
	Gleitman, H., & Gross, J. (2011). Psychology (8th international student ed.). New York, NY: W. W. Norton & Company.
	Hengeveld, M. W., & Van Balkom, A. J. L. M. (2009). Leerboek psychiatrie (2nd ed.). Utrecht: De Tijdstroom.
	Nevid, J. S., Rathus, S. A., & Greene, B. (2016). Psychiatrie: Een inleiding (8th ed.). Amsterdam: Pearson.
	Swaab, H., Bouma, A., & Hendriksen, J. (eds) (2011). Klinische kinderneuropsychologie (1st ed.). Amsterdam: Boom.
	Kerig, P., Ludlow, A., & Wenar, C. (2012). Developmental psychopathology (6th ed.). New York, NY: McGraw-Hill Education.
	Kolb, B., & Whishaw, I. Q. (2014). An introduction to brain and behavior (4th ed.). New York, NY: Worth Publishers.
	Nolen-Hoeksema, S. (2014). Abnormal psychology (6th international student ed.). New York, NY: McGraw-Hill Education.
	Siegler, R. S., DeLoache, J. S., Eisenberg, N., & Saffron, J. (2014). How children develop. New York, NY: Worth Publishers.
	Smeets, G., Bos, E. R., van der Molen, H. T., & Murris, P. (2009). Klinische psychologie: Diagnostiek en therapie (2nd ed.). Groningen, the Netherlands: Wolters-Noordhoff.
	Van Lieshout, T. (2009). Pedagogische adviezen voor speciale kinderen (2nd ed.). Houten, the Netherlands: Bohn Stafleu Van Loghum.
	Vandereycken, W., Hoogduin, C. A. L., & Emmelkamp, P. M. G. (2008). Handboek psychopathologie: Deel 1 basisbegrippen. Houten, the Netherlands: Bohn Stafleu van Loghum.
	Verschueren, K., & Koomen, H. (2008). Handboek diagnostiek in de leerlingenbegeleiding (1st ed.). Antwerpen: Garant.
	Yeates, K. O., Ris, M. D., Taylor, H. G., & Pennington, B. F. (2010). Pediatric neuropsychology: research, theory, and practice. (2nd ed.). New York, NY: Guilford Publications.
Elaborate (n = 10)	Carlson, N. R. (2013). Physiology of behavior (11th international ed.). New Jersey, NJ: Pearson Education.
	Carr, A. (2016). The handbook of child and adolescent clinical psychology: A contextual approach (3rd ed.). New York, NY: Taylor & Francis.
	Doreleijers, T. A. H., Boer, F., Huisman, J., & Haan, E. H. F. (eds) (2013). Leerboek psychiatrie kinderen en adolescenten (2nd ed.). Utrecht: De Tijdstroom.
	Farah, M. J., & Feinberg, T. E. (2006). Patient-based approaches to cognitive neuroscience (2nd ed.). Cambridge, MA: MIT Press.
	Higgins, E. S., & George, M. S. (2013). Neuroscience of clinical psychiatry: The pathophysiology of behavior and mental illness (2nd ed.). Philadelphia, PA: Wolters Kluwer Health.
	Prins, P. J. M., & Braet, C. (2014). Handboek klinische ontwikkelingspsychologie (2nd ed.). Houten: Bohn Stafleu van Loghum.
	Thapar, A., Pine, D. S., Leckman, J. F., Scott, S., Snowling, M. J., & Taylor, E. A. (2015). Rutter’s child and adolescent psychiatry (6th ed.). Chichester: John Wiley & Sons.
	Verhulst, F. C. (2015). Leerboek kinder—En jeugdpsychiatrie (4th ed.). Assen: Koninklijke Van Gorcum.
	Verhulst, F. C., Verheij, F., & Danckaerts, M. (2014). Kinder—En jeugdpsychiatrie (1st ed.). Assen: Koninklijke Van Gorcum.
	Wicks-Nelson, R. (2015). Abnormal child and adolescent psychology with DSM-5 update (8th ed.). New York, NY: Taylor & Francis.