Sexually dimorphic reactions to fear

The burden of an anxiety disorder on a sufferers life can be dramatic and sustained, often contributing to a considerable  drop in an individual’s quality of life. It is therefore crucial that the cause of this set of disorders can be identified, in order  to help to develop an effective treatment.

The brain circuitry and neurobiology of the fear response may be linked to anxiety, as it has been suggested that  dysregulations in the associated brain regions may be related to the pathology of anxiety related disorders. Major regions  implicated in fear conditioning and anxiety are the amygdala, hippocampus, hypothalamus, medial prefrontal cortex  (mPFC) and brain-stem nuclei, and interestingly, these regions have also been suggested to be sexually dimorphic.  Therefore, the physiological response of males and females to fear may be different; this could imply that there are  differences in pathology of anxiety disorders in males and females.

In a study published in Biology of Mood & Anxiety Disorders this week, fMRI and a fear conditioning and extinction  paradigm was used to investigate sex differences in the fear circuitry of men and women. Lebron-Milad et al. found a  significant difference in brain activation, yet corresponding levels of peripheral autonomic response remained similar in men and women. The authors have suggested that this may indicate that men and women use different neural strategies to produce homeostasis in the brain and in response to fear.This has broader implications in inferring the biological basis of anxiety disorders, and leading on from this, the differential treatment of men and women suffering from anxiety disorders.

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