Neurology Central

Recent meta-analysis suggests a neurochemical difference between anxiety disorders in humans

A meta-analysis carried out by researchers from the University of São Paulo (Brazil), Imperial College London (UK), University of Western Australia (Perth, Australia) and the University of Toronto (ON, Canada), that aimed to evaluate the role of serotonin in various anxiety disorders, has indicated that previous disorder groupings may not be accurate based on serotonergic functioning.

Using data pooled from six studies of remitted fear/anxiety patients exposed to syndrome-specific aversive stimulation under acute tryptophan depletion, the team evaluated whether results supported Deakin and Graeff’s previously published theory of the dual role of serotonin in response to varying threats. The results confirmed that the inconsistencies observed in the studies did indeed fit with the hypothesis, with serotonin identified as being critical to prevent fear and panic, but not in the prevention of anxiety.

“The idea of responses to threatening stimuli causing feelings and emotions related to fear and anxiety, as well as a myriad of subgroups within these responses, is not new. However, our study gives an important step towards subclustering of disorders once it is based on one of the most important neurotransmitters involved in these reactions and in the fact that it was tested in actual psychiatric patients” explained lead author, Felipe Corchs (University of São Paulo).

This differential response to reduced serotonin levels is potentially important in the current, ongoing effort to recategorize psychiatric disorders based on etiological variables, and gives support to the dissociation of the disorders traditionally grouped together under anxiety-related disorders. The team also believe that information such as this may help to inform further development of treatments for these psychiatric disorders.

Sources: Sage Publications press release via EurekAlert!; Corchs F, Nutt DJ, Hince DA, Davies SJ, Bernik M, Hood SD. Evidence for serotonin function as a neurochemical difference between fear and anxiety disorders in humans? J. Psychopharmacol. doi:10.1177/0269881115590603 (2015) (Epub ahead of print).