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Serotonergic contribution to boys' behavioral regulation.

Nantel-Vivier A, Pihl RO, Young SN, Parent S, Bélanger SA, Sutton R, Dubois ME, Tremblay RE, Séguin JR - PLoS ONE (2011)

Bottom Line: However, boys in the tryptophan group adjusted their level of responding optimally as a function of the level of provocation, whereas boys in the control group significantly decreased their level of responding towards the end of the competition.Boys in the tryptophan group tended to show greater perspective taking, tended to better distinguish facial expressions of fear and happiness, and tended to provide greater instrumental help to the experimenter.The present study provides initial evidence for the feasibility of acute tryptophan supplementation in children and some effect of tryptophan supplementation on children's behaviors.

View Article: PubMed Central - PubMed

Affiliation: Psychology Department, McGill University, Montreal, Canada.

ABSTRACT

Objectives: Animal and human adult studies reveal a contribution of serotonin to behavior regulation. Whether these findings apply to children is unclear. The present study investigated serotonergic functioning in boys with a history of behavior regulation difficulties through a double-blind, acute tryptophan supplementation procedure.

Method: Participants were 23 boys (age 10 years) with a history of elevated physical aggression, recruited from a community sample. Eleven were given a chocolate milkshake supplemented with 500 mg tryptophan, and 12 received a chocolate milkshake without tryptophan. Boys engaged in a competitive reaction time game against a fictitious opponent, which assessed response to provocation, impulsivity, perspective taking, and sharing. Impulsivity was further assessed through a Go/No-Go paradigm. A computerized emotion recognition task and a staged instrumental help incident were also administered.

Results: Boys, regardless of group, responded similarly to high provocation by the fictitious opponent. However, boys in the tryptophan group adjusted their level of responding optimally as a function of the level of provocation, whereas boys in the control group significantly decreased their level of responding towards the end of the competition. Boys in the tryptophan group tended to show greater perspective taking, tended to better distinguish facial expressions of fear and happiness, and tended to provide greater instrumental help to the experimenter.

Conclusions: The present study provides initial evidence for the feasibility of acute tryptophan supplementation in children and some effect of tryptophan supplementation on children's behaviors. Further studies are warranted to explore the potential impact of increased serotonergic functioning on boys' dominant and affiliative behaviors.

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Related in: MedlinePlus

Points taken away (A) and decision time (B) at each phase of the competitive reaction time game.Values represent change (z score) in points taken away and decision time at each phase of the game, relative to the no provocation baseline.
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pone-0020304-g002: Points taken away (A) and decision time (B) at each phase of the competitive reaction time game.Values represent change (z score) in points taken away and decision time at each phase of the game, relative to the no provocation baseline.

Mentions: Within-subject repeated measures analyses were performed separately for each group to assess patterns of response to varying levels of provocation by the fictitious opponent. The groups did not differ at baseline on points taken away and decision time. As described above, scores on these measures were standardized relative to the no-provocation baseline. As illustrated in Figure 2a, provocation level had a significant effect on points taken away for the control group (F(1.46)  = 7.37, p = 0.01) but to a lesser extent for the tryptophan group (F(3)  = 2.30, p = 0.10). Planned comparisons revealed that boys in the control group tended to take away more points than at baseline during the high provocation phase (z = 0.36, F(1)  = 3.81, p = 0.08, d = 0.45) and significantly decreased the number of points they took away during the last phase of the game (z  =  −0.77, F(1)  = 5.00, p = 0.05, d  =  −0.93). For the tryptophan group, the only significant change in number of points taken away relative to baseline was an increase during the high provocation phase of the game (z = 0.59, F(1)  = 6.31, p = 0.03, d = 0.64). Groups differed in points taken away during the last phase (t(15.43)  =  −2.40, p = 0.03). As shown in Figure 2b, provocation level had a significant effect on decision time for both the control group (F(3)  = 4.06, p = 0.02) and the tryptophan group (F(1.84)  = 4.33, p = 0.03). Boys in the control group significantly decreased their decision time relative to baseline during the high provocation (z  =  −0.62, F(1)  = 4.87, p = 0.05, d  =  −0.72) and low provocation (z  =  −0.86, F(1)  = 10.21, p = 0.01, d  =  −0.95) phases of the game. Boys in the tryptophan group significantly decreased their decision time relative to baseline only during the high provocation phase (z  =  −1.10, F(1)  = 16.36, p<0.01, d  =  −1.26).


Serotonergic contribution to boys' behavioral regulation.

Nantel-Vivier A, Pihl RO, Young SN, Parent S, Bélanger SA, Sutton R, Dubois ME, Tremblay RE, Séguin JR - PLoS ONE (2011)

Points taken away (A) and decision time (B) at each phase of the competitive reaction time game.Values represent change (z score) in points taken away and decision time at each phase of the game, relative to the no provocation baseline.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105989&req=5

pone-0020304-g002: Points taken away (A) and decision time (B) at each phase of the competitive reaction time game.Values represent change (z score) in points taken away and decision time at each phase of the game, relative to the no provocation baseline.
Mentions: Within-subject repeated measures analyses were performed separately for each group to assess patterns of response to varying levels of provocation by the fictitious opponent. The groups did not differ at baseline on points taken away and decision time. As described above, scores on these measures were standardized relative to the no-provocation baseline. As illustrated in Figure 2a, provocation level had a significant effect on points taken away for the control group (F(1.46)  = 7.37, p = 0.01) but to a lesser extent for the tryptophan group (F(3)  = 2.30, p = 0.10). Planned comparisons revealed that boys in the control group tended to take away more points than at baseline during the high provocation phase (z = 0.36, F(1)  = 3.81, p = 0.08, d = 0.45) and significantly decreased the number of points they took away during the last phase of the game (z  =  −0.77, F(1)  = 5.00, p = 0.05, d  =  −0.93). For the tryptophan group, the only significant change in number of points taken away relative to baseline was an increase during the high provocation phase of the game (z = 0.59, F(1)  = 6.31, p = 0.03, d = 0.64). Groups differed in points taken away during the last phase (t(15.43)  =  −2.40, p = 0.03). As shown in Figure 2b, provocation level had a significant effect on decision time for both the control group (F(3)  = 4.06, p = 0.02) and the tryptophan group (F(1.84)  = 4.33, p = 0.03). Boys in the control group significantly decreased their decision time relative to baseline during the high provocation (z  =  −0.62, F(1)  = 4.87, p = 0.05, d  =  −0.72) and low provocation (z  =  −0.86, F(1)  = 10.21, p = 0.01, d  =  −0.95) phases of the game. Boys in the tryptophan group significantly decreased their decision time relative to baseline only during the high provocation phase (z  =  −1.10, F(1)  = 16.36, p<0.01, d  =  −1.26).

Bottom Line: However, boys in the tryptophan group adjusted their level of responding optimally as a function of the level of provocation, whereas boys in the control group significantly decreased their level of responding towards the end of the competition.Boys in the tryptophan group tended to show greater perspective taking, tended to better distinguish facial expressions of fear and happiness, and tended to provide greater instrumental help to the experimenter.The present study provides initial evidence for the feasibility of acute tryptophan supplementation in children and some effect of tryptophan supplementation on children's behaviors.

View Article: PubMed Central - PubMed

Affiliation: Psychology Department, McGill University, Montreal, Canada.

ABSTRACT

Objectives: Animal and human adult studies reveal a contribution of serotonin to behavior regulation. Whether these findings apply to children is unclear. The present study investigated serotonergic functioning in boys with a history of behavior regulation difficulties through a double-blind, acute tryptophan supplementation procedure.

Method: Participants were 23 boys (age 10 years) with a history of elevated physical aggression, recruited from a community sample. Eleven were given a chocolate milkshake supplemented with 500 mg tryptophan, and 12 received a chocolate milkshake without tryptophan. Boys engaged in a competitive reaction time game against a fictitious opponent, which assessed response to provocation, impulsivity, perspective taking, and sharing. Impulsivity was further assessed through a Go/No-Go paradigm. A computerized emotion recognition task and a staged instrumental help incident were also administered.

Results: Boys, regardless of group, responded similarly to high provocation by the fictitious opponent. However, boys in the tryptophan group adjusted their level of responding optimally as a function of the level of provocation, whereas boys in the control group significantly decreased their level of responding towards the end of the competition. Boys in the tryptophan group tended to show greater perspective taking, tended to better distinguish facial expressions of fear and happiness, and tended to provide greater instrumental help to the experimenter.

Conclusions: The present study provides initial evidence for the feasibility of acute tryptophan supplementation in children and some effect of tryptophan supplementation on children's behaviors. Further studies are warranted to explore the potential impact of increased serotonergic functioning on boys' dominant and affiliative behaviors.

Show MeSH
Related in: MedlinePlus