Searching for Biological Markers of Personality: Are There Neuroendocrine Markers of Anxiety?

The existence of stable individual differences in cognitive and emotional capabilities both in animals and humans is well-accepted. The theories of personality assume that such individ‐ ual differences can be categorized and that the richness of individual differences in humans would be the result of the combination of differences in a few underlying personality fac‐ tors. The most accepted contemporary theory is that of “Big Five” [1] that consider five high‐ est order factors: neuroticism, extraversion, openness, agreeableness and conscientiousness. However, the nature of some of the putative factors is still a matter of dispute in the differ‐ ent theories. Within this framework, the factors extraversion and neuroticism have been as‐ sociated to the response to positive and negative emotions, respectively. Moreover, it is typically distinguished between personality and temperament, the latter term referring to biological predisposition that is noted early in life and will eventually lead to adult person‐ ality [2]. Emotionality may be considered as relatively stable individual characteristic so that subjects labeled as highly emotional will strongly react to emotional stimuli, particularly negative ones. It is of interest to know how high neuroticism subjects react to stressful situa‐ tions and which are the consequences of such exposure. It has been reported that in re‐ sponse to an adverse event high neuroticism soldiers showed larger increases in psychiatric symptoms than low neuroticism subjects [3], but no differences in the response were ob‐ served after controlling for pre-trauma symptoms. These data question the existence of high stress responsiveness in high neuroticism subjects.