SUMMARY OF THE PAPER OF THE ROLE OF
PARENTING AND DOPAMINE D4 RECEPTOR
GENE POLYMORPHISMS IN CHILDRENS’S
INHIBITORY CONTROL
PAPER WRITTEN BY: HEATHER J. SMITH, KATIE R.
KRYSKI, HAROON I. SHEIKH, SHIVA M. SINGH AND
ELIZABETH P. HAYDEN
SUMMARY MADE BY
KENAN CETINEL
TERMINOLOGY
• Polymorphism: The presence of two or more allelic forms in a species, the
variation is correctly referred to as polymorphism (“many morphs”) when
the alternative forms are common. Retrieved from
http://www.stats.ox.ac.uk/~harding/files/Prelims/RHarding_HTLect2_Poly
morphism_2007.pdf
•
Dopamine: In the brain, dopamine functions as a neurotransmitter—a
chemical released by nerve cells to send signals to other nerve cells. The
brain includes several distinct dopamine systems, one of which plays a
major role in reward-motivated behavior. Retrieved from
https://en.wikipedia.org/wiki/Dopamine
• Allele: One of a number of alternative forms of the same gene. Retrieved
from https://en.wikipedia.org/wiki/Allele
• Tandem Repeat: Occur in DNA when a pattern of one or more nucleotides
is repeated and the repetitions are directly adjacent to each other. Retrieved
from https://en.wikipedia.org/wiki/Tandem_repeat
• Variable Number Tandem Repeat (VNTR): A location in a genome where a
short nucleotide sequence is organized as a tandem repeat. These can be
found on many chromosomes, and often show variations in length between
individuals. Retrieved from
https://en.wikipedia.org/wiki/Variable_number_tandem_repeat
• Ribonucleic acid (RNA): A polymeric molecule implicated in various
biological roles in coding, decoding, regulation, and expression of genes.
Retrieved from https://en.wikipedia.org/wiki/RNA
INTRODUCTION
•
EFFORTFUL CONTROL: Ability to inhibit a dominant response in order
to engage in a subdominant response (Rothbart, Ellis, Rueda & Posner,
2003, p. 1114).
– Deliberative and Strategic (Carver, Johnson & Joormann, 2008)
– Plays an important role in
• Facilitating attentional focusing and shifting
• Error detection
• The suppression of inappropriate responses
• Foresight (Rothbart, 2007).
– Start to appear around 12 month of age
– Develops rapidly in early preschool years
– Continues to mature into early adulthood (Kochanska, Murray &
Harlan, 2000).
THE IMPORTANCE OF DOPAMINE D4 RECEPTOR
Origins of Effortful Control
•
•
•
•
•
Twin studies implicates a powerful genetic influence on effortful control, with
heritability as high as 79% (Goldsmith, Buss & Lemery, 1997).
Posner and Fan (2005) and Rothbart et al. (1994b) defined individual differences in
effortful control as variations in the productivity of a network of brain locations
named as EXECUTIVE ATTENTION NETWORK.
Primary neurotransmitter of this executive attention network is DOPAMINE
(Posner & Fan, 2005).
This executive attention network receives projections from ventral tegmental
area(VTA) which is the origin of dopaminergic cell bodies.
Also cingulate cortex (limbic cortex) is particularly rich in dopamine supplies.
–
•
Especially DOPAMINE D4 (DRD4) receptors are found in large numbers in this area (Boy et al.,
1998).
Thus we can say that dopamine is an important factor in executive attention and
effortful control
EFFECT OF 7-REPEAT ALLELE
• The dopamine D4 gene (DRD4) is higly polymorpic (Wang,
Ding, Flodman, Kidd, Kidd, Grady, Ryder, Spence, Swanson
& Moyzis, 2004).
• Among those polymorpisms, one of them, a variable number
tandem repeat(VNRT) receives much more attention than
others because of its influence on effort control.
• Compared to other VNRT’s, 7-repeat allele decreases (Asgari
et al., 1995 and Schoots & Van Tol, 2003 and van
Craenenbroeck et al., 2005)
– Signal transduction productivity
– RNA stability
– Protein folding efficiancy
• To sum up, these factors have results, such as;
– A substantial decrease in signaling
– Impairment in functioning of neural circuts:
which are have an effect on EFFORTFUL CONTROL .
• For example many studies regularly mentioned the relationship
between 7-repeat allele and attention deficit hyperactivity
disorder(ADHD) (e.g. Faraone, Doyle, Mick & Biederman,
2001; Li, Sham, Owen & He, 2006; Maher, Marazita, Ferrell
& Vanyukov, 2002)
EFFECT OF PARENTING IN EFFORTFUL
CONTROL
• An addition to genetics, effortful control is also influenced by social
experiences, such as; parenting styles (Campos, Campos & Barrett, 1989;
Gottman, Katz & Hooven, 1997; Karreman, van Tuijl, van Aken &
Dekovic, 2006).
• For instance Hoffman in 2000 suggested that,
– Hostile parenting
• Positive emotions
children’s level of negative emotionality
cognitive flexibility
– Thus parenting styles that elicit positive emotions in children may result in an improved
effortful control (Ashby, Isen & Turken, 1999).
• In addition (Zhou et al., 2004) proposed that parents who
– Encourage children autonomy
– Provide a good structure
Necessary for children to improve their effortful conrtol strength.
ASSOCIATION BETWEEN DRD4 AND
PARENTING
• Although parenting plays a key role in children’s effortful
control, the effect of it differs depending on whether they have
7-repeated allele or not.
• For example, maternal loss or trauma is associated with
disorganized attechment but only in infants with a 7-repeat
allele (Van Ijzendoorn & Bakermans-Kranenburg, 2006).
• Furthermore, a research that examined the link between DRD4
exon III VNTR polymorphisms and parenting and if the link
predicts an effortful control.
– Results implicated that
positive parenting leads to a greater
senseations seeking in children with the 7-repeat allele than those
without (Sheese et al., 2007).
CURRENT STUDY
• Current study examines the role of DRD4 exon III VNTR and parenting in
children’s effortful control.
• In detail this paper emphasis on an aspect of efforful control which is
Inhibitory Control(IC) that defines as
– Ability to inhibit (prevent) impulsive behaviour depending on social or
contextual motivation (Rothbart, Ahadi & Hershey, 1994a).
• Inhibitory Control(IC) is important for variety of issues. Such as;
– Development of Conscience
– Development of Theory of Mind
– Relationship to attention-deficit/hyperactivity disorder(ADHD)
(Carlson & Moses, 2001; Kochanska & Aksan, 2006; Schachar, Mota,
Logan, Tannock & Klim, 2000).
• This study expects factors such as;
– Parent sensitivity
– Supportive presence
– Positive affectivity
– Confidence
would result in greater level of child’s IC.
• Also with negative parenting indicators such as;
– Intrusiveness
– Hostility
– Negative affectivity
– Detachment
would result in lower level of child’s IC.
• Finally, with the litareture research saying DRD4 7-repeat allele sensitisize
children more to parenting influences,;
– This paper predicts that parenting influences would be more significant
in children with DRD4 7-repeat allele
METHODOLOGY
• Participants
– 409 children between the ages of 36-47 months
old were randomly selected
– Primary caregivers were mostly mothers
– 90% of children were Cauacasian
– Children were with avarage cognitive ability. These
abilities were tested by Peabody Picture TestFourth Edition
• Labrotary Assessment of IC(Inhibitory Control)
– Children participated in IC tests to
• Elicit behaviour
• Evoke emotion
• Asess multiple facets of child temperament
– Children’s primary caregivers were present but
instructed to remain uninvolved
– Tower of Patience
– Snack Delay
RESULTS
• No direct relationship found between IC(Inhibitory Control)
and presence/absence of a 7-repeat allele
• Children whose parents behaved in levels of positive
parenting showed IC, at the same time opposite situation
happened.
• For children with a copy of a 7-repeat allele, higher levels of
positive parenting were substiantially linked with greater IC;
on the contrary without a copy of a 7-repeat allele, positive
parenting was not significantly linked with IC.
DISCUSSION
• The impact of children’s DRD4 7-repeat condition on
emerging effortful control is moderating by parenting which is
consistent with previous study (Smith et al., in press)
• Consistently with the litareture this study proposes when
positive parenting is meaningfully low with children with a 7repeat, their IC is low as well. This situation didn’t happen for
those without a 7-repeat allele.
• This overall pattern suggests that parent supportion presence
and parental engagement may be especially associated to
children’s early-emerging IC, at least for children with
spesific genetic variants!!!!
CONTINUES IN DISCUSSION
• The dynamics of which positive parenting balances the effect
of the DRD4 on children’s are unknown!!!
• But this study reccomends that dopamine plays a key role in
reward and punishment and may have an impact on cognitive
flexibilty which this has been said that is required for IC
• Knowing that 7-repeat allele leads to a decreased
dopaminergic signalling, that the effect of the 7-repeat on
cognitive flexibility is more easily prevented in the absence of
reward.
• Therefore, it can be said that positive parenting behaviors
may provide a key context of reward that mitigates children’s
genetic heredities!!!
LIMITATIONS
• Effortful control is defined as multidimensional construct
(Rothbart, Ahadi, Hershey & Fisher, 2001), but this research’s
focus just on one dimension of efforful control that is
IC(Inhibitory Control)
• Secondly while there are other genetic variants that influence,
we put emphasis on just one.
• Thirdly and finally, the current study examined IC independent
of additional temperament traits; however, as previously
discussed by Derryberry and Rothbart (1997), behavioral
outcomes are likely a function of both effortful control and
other reactive temperament traits, such as surgency, negative
affect and impulsivity.