Peter Hartmann

COMT Genetic Variation Affects Fear Processing: Psychophysiological Evidence

Emotional dysregulation is a core characteristic of many psychiatric diseases, including the anxiety disorders. Although heritable influences account for a significant degree of variation in risk for such disorders, relatively few candidate susceptibility factors have been identified. A coding variant in one such gene, encoding the dopamine catabolic enzyme catechol-O-methyltransferase (COMT Val158Met), has previously been associated with anxiety and with anxiety-related temperament and altered neural responses to affective stimuli in healthy individuals. In 96 healthy women recruited from a sample of 800 participants according to genotype, the authors tested for an association between the DRD2/ANKK1 Taq Ia, the COMT Val158Met, and a psychophysiological measure of emotion processing, the acoustic affective startle reflex modulation (ASRM) paradigm, and found that COMT genotype significantly affected startle reflex modulation by aversive stimuli, with Met158 homozygotes exhibiting a markedly potentiated startle reflex compared with Val158 carriers. A trait measure of anxiety (Grays Behavioral Inhibition System; J. A. Gray & N. McNaughton, 2000) was also associated with ASRM. The functional polymorphism in the dopamine D2 receptor (DRD2/ANKK1 Taq Ia) had no effect on startle modulation. The findings support prior genetic and neuroimaging associations of the COMT 158Met allele to affective psychopathology and alterations in neural systems for emotional arousal and regulation.

The reliability and validity of the Danish Draft Board Cognitive Ability Test: Børge Prien's Prøve.

The Danish Draft Board has used the same test for assessing general cognitive ability, the Børge Priens Prøve (BPP), for over 50 years during which time all men on reaching the age of 18 become liable for conscription. Data from the test has, over the decades, been used in numerous and wide-ranging research studies. Nonetheless, owing to the special circumstances of its administration, some psychometric properties, which are generally assessed for psychological tests, have not previously been investigated for the BPP. First, since the test is only used at the assessment phase, retesting with the BPP occurs only rarely and under exceptional circumstances. Therefore, its Test-Retest reliability has hitherto not been documented. Second, questions have often been raised as to whether the validity of the BPP is undermined by either a lack of motivation and under-performing among some of the men taking the test, being, as they are, compelled to do so, and/or by gradual obsolescence of the test over the decades of its use. We here present findings from three new studies to show that (a) the BPP has a satisfactory Test-Retest reliability, r=0.77, (b) BPP test scores are not positively associated with expressed attitude to being called upon to serve conscription and (c) the correlation between the BPP and a measure of educational level has remained stable (at about 0.5) through the last two decades. Taken together these three findings further support the continuing value of the BPP in research relating to cognitive ability.

D2 receptor density and prepulse inhibition in humans: Negative findings from a molecular genetic approach

There is plenty of evidence from schizophrenia research and psychopharmacological experiments showing the influence of the dopaminergic neurotransmission on the prepulse inhibition (PPI). A lot of insights into the underlying neural mechanisms of the PPI have been gained from animal models, which are in need to be validated in humans. Due to new technological advances, findings from psychopharmacological challenge tests can now be verified with techniques from molecular genetics which provide an elegant non-invasive approach. To close the gap between animal research and research in humans in this field a molecular genetic approach was applied to investigate the neural mechanisms of the PPI in healthy subjects. In N=96 female participants recruited out of a sample of N=800 subjects according to their genotypes we tested the association between the DRD2 Taq Ia and the COMT Val158Met polymorphisms, and the magnitude of the eye-blink reflex in an acoustic PPI paradigm. Neither significant influences of both dopaminergic single nucleotide polymorphisms nor an epistasis effect could be detected. Although findings do not support the hypothesis that two of the most prominent dopaminergic candidate loci (DRD2 Taq Ia and COMT Val158Met) effect PPI the study does not exclude the relevance of the dopaminergic system in general. Further molecular genetic studies investigating other variants on dopaminergic genes have to be conducted.

Personality as Predictor of Achievement

General intelligence, g, is a powerful predictor of education, job status and income, but the predictive power of personality is less clear. The objective of the present paper was to investigate the predictive power of personality (and g) with respect to education, job status, and income. We derived Eysenckian personality factors (P, E, N, L) from MMPI data; g was distilled from a large number of highly diverse cognitive variables. Linear, nonlinear, and interaction power in predicting socioeconomic achievement in 4200+ middle-aged American males was tested. In the present study, broad personality factors provided little incremental validity to g, in predicting socioeconomic achievement across type of education and job categories. This is at odds with previous studies, and does not exclude the possibility that certain personality factors (higher or lower order) have more predictive validity within certain job categories and education types.

Et århundrede efter Spearmans g

Hartman, P. (2004). A Century after Spearmans g. Nordisk Psykologi, 56 (1) 3–18. 100 years ago Spearman discovered that all cognitive ability tests had one common factor that could account for the majority of the common variance among all these cognitive ability tests. He labelled this general factor the g factor. The g factor is found across sex, age, nationality and culture which points to the robustness of g as a statistical construct. The g factor can be measured and estimated adequately through the use of several cognitive ability tests followed by a factor analysis. The g factor is more than advanced statistics it is also a biological phenomenon. The heritability of g factor scores amount to 40–80% depending on the age of the subjects. Furthermore, several correlations between g factor scores and physiological processes have been found, all pointing to the fact that the g factor is rooted in biology. The g factor also has major implications for social life, which is seen by the fact that g factor scores correlate with a host of social behaviour like obtained education, learning ability and job performance. This is not to say that a persons g factor score controls the destiny of that person. Other factors like personality, luck and such, also influence the social behaviour of that person. In conclusion, although the g factor is not the only relevant factor in regards to the understanding of cognitive abilities and its structure, it is certainly the most important one.