DRD4 related to infant attention and information processing: a developmental link to ADHD?

The dopamine D4 receptor (DRD4) exon III polymorphism has generated interest because of its association with attention deficit hyperactivity disorder (ADHD), with an increased frequency of the seven-repeat allele being reported in children with ADHD. Deficits in sustained attention and information processing characterize ADHD, and individual differences in these functions are apparent from infancy. We found that in a structured play situation and on an information-processing task, 1-year-old infants with the 7-DRD4 allele showed less sustained attention and novelty preference than do infants without the 7-DRD4 allele. There was also a significant interaction between DRD4 and the serotonin transporter promoter (5-HTTLPR) gene on a measure of sustained attention. Our results provide evidence for a possible developmental link between DRD4 and ADHD via early sustained attention and information processing. It also points to the importance of considering the influence of more than one gene in studies of behavior.

Olanzapine treatment of clozapine-induced NMS

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Dopamine D4 receptor (D4DR) and serotonin transporter promoter (5-HTTLPR) polymorphisms in the determination of temperament in 2-month-old infants

We and others have previously shown that the dopamine D4 exon III repeat (D4DR) and the serotonin-transporter promoter region (5-HTTLPR) polymorphisms are not only associated with adult personality traits1-7 but also with temperament in 2-week-old neonates.8 We now report the results of a second study of these infants and their temperament at 2 months using Rothbart's Infant Behavior Questionnaire (IBQ).9 There were significant negative correlations between neonatal orientation and motor organization as measured by the Neonatal Behavioral Assessment Scale (NBAS)10 at 2 weeks and negative emotionality, especially distress in daily situations, at 2 months of age. There were significant main effects for negative emotionality and distress when the infants were grouped by the D4DR and the 5-HTTLPR polymorphisms. Infants with long D4DR alleles had significantly lower scores on Negative Emotionality (F[1, 72] = 8.50, P = 0.005) and Distress to Limitations (F[1,72] = 4.93, P = 0.03) than infants with short D4DR alleles. In contrast, infants with the short homozygous (s/s) 5-HTTLPR genotype had higher scores on Negative Emotionality (F[1,72] = 3.88, P = 0.053) and Distress to Limitations (F[1,72] = 4.94, P = 0.029) than infants with the I/s or I/I genotypes. The strongest effects occurred in those infants with the s/s 5-HTTLPR polymorphism who also were lacking long D4DR alleles which in some studies has been linked to adult novelty seeking.1,6 These infants showed most negative emotionality and most distress to daily situations, temperament traits that are perhaps the underpinning of adult neuroticism.

Dopamine D4 receptor and serotonin transporter promoter in the determination of neonatal temperament

Genetic effects on behavior were evaluated at a time in early development when we hypothesized that environmental influences are minimal and least likely to confound associations between temperament and genes. The behavioral effects of two common polymorphisms linked respectively in some, but not all, studies to novelty seeking (dopamine D4 receptor-D4DR) and neuroticism and harm avoidance (serotonin transporter promoter region-STPR) were examined in a group of 81 two-week-old neonates. Neonate temperament was evaluated using the Brazelton neonatal assessment scale (NBAS). Multivariate tests of significance showed a significant association of D4DR across four behavioral clusters pertinent to temperament including orientation, motor organization, range of state and regulation of state. A significant multivariate interaction was also observed between D4DR and STPR. The effect of the homozygous short STPR genotype (s/s) was to lower the orientation score for the group of neonates lacking the long form (L) of D4DR. When adult subjects were grouped by the STPR polymorphism there is no significant effect of L-D4DR in those subjects homozygous for the STPR short form (s/s) whereas in the group without the homozygous genotype the effect of L-D4DR is significant and accounts for 13% of the variance in novelty seeking scores between groups.

Slow magnetic stimulation of prefrontal cortex in depression and schizophrenia

1. The authors used transcranial magnetic stimulation (TMS) of pre-frontal cortex to study mood changes in 10 depressed patients and 10 schizophrenic patients. 2. A slow rate of stimuli was used, one per 30 seconds; maximal intensity of about 2 Tesla was given for 30 stimuli, 15 on each side of the brain. 3. No side effects were seen and at least three depressed patients and two schizophrenic patients appeared to improve, at least transiently. 4. These results suggest that rapid rate TMS may not be necessary to elicit mood effects.

Pitch changes during attempted deception

Two studies on speech samples from 32 male college students are reported. In the first, it was shown that the average voice fundamental frequency of the subjects was higher when lying than when telling the truth. In the second, judges rated the truthfulness of 64 true and false utterances either from an audiotape that had been electronically filtered to render the semantic content unintelligible or from an unfiltered tape. The truthfulness ratings of the judges who heard the content-filtered tape were negatively correlated with fundamental frequency, whereas for the unfiltered condition, truthfulness ratings were uncorrelated with pitch. Although raings made under the two conditions did not differ in overalll accuracy, accuracy differences were found that depended on how an utterance had been elicited originally.

Pitch changes during attempted deception

Two studies on speech samples from 32 male college students are reported. In the first, it was shown that the average voice fundamental frequency of the subjects was higher when lying than when telling the truth. In the second, judges rated the truthfulness of 64 true and false utterances either from an audiotape that had been electronically filtered to render the semantic content unintelligible or from an unfiltered tape. The truthfulness ratings of the judges who heard the content-filtered tape were negatively correlated with fundamental frequency, whereas for the unfiltered condition, truthfulness ratings were uncorrelated with pitch. Although raings made under the two conditions did not differ in overalll accuracy, accuracy differences were found that depended on how an utterance had been elicited originally.