Delineating physiologic defensive reactivity in the domain of self-report: phenotypic and etiologic structure of dispositional fear.
BACKGROUND
Individual differences in fear and fearlessness have been investigated at their extremes in relation to markedly different forms of psychopathology--anxiety disorders and psychopathy, respectively. A documented neural substrate of fear-related traits and disorders is defensive reactivity as reflected in aversive startle potentiation (ASP).


METHODS
The current study extended prior work by characterizing, in a sample of adult twins from the community (n = 2511), the phenotypic and etiologic structure of self-report measures of fear and fearlessness known to be associated with ASP.


RESULTS
Analyses revealed a hierarchical structure to the trait fear domain, with an overarching, bipolar fear/fearlessness dimension saturating each measure in this domain, and subfactors labeled 'distress,' 'stimulation seeking' and 'sociability' accounting for additional variance in particular measures. The structure of genetic and non-shared environmental associations among the measures closely mirrored the phenotypic structure of the domain.


CONCLUSIONS
The findings have implications for proposals to reconceptualize psychopathology in neurobiological terms.
University of Minnesota - Twin Cities, Minneapolis, MN 32306-4301, USA.
M D
MD
Kramer
C J
CJ
Patrick
R F
RF
Krueger
M
M
Gasperi
D000293:Adolescent; D000328:Adult; D000987:Antisocial Personality Disorder / Q000453:epidemiology / Q000235:genetics / Q000523:psychology; D001699:Biometry / Q000379:methods; D005163:Factor Analysis, Statistical; D005239:Fear / Q000502:physiology*; D005260:Female; D006801:Humans; D007206:Individuality; D008297:Male; D015233:Models, Statistical; D010551:Personality / Q000235:genetics / Q000502:physiology*; D010555:Personality Inventory; D010641:Phenotype; D013216:Reflex, Startle / Q000235:genetics / Q000502:physiology*; D057566:Self Report; D012931:Social Environment; D055815:Young Adult