Psychobiological correlates of allostatic overload in a healthy population.

The concept of allostatic load (AL) represents the cost of the continual adjustment of the internal milieu required by an organism to adapt to different challenges. The majority of studies concerning AL have focused mainly on identifying its biological components. Recently, new criteria for a clinimetric evaluation of AL have been introduced, adding a new definition of allostatic overload (AO). This study aims to identify psychological and biological correlates of AO in a population of blood donors, according to this new definition of AO. Participants included 240 blood donors recruited from May 2007 to December 2009 in 4 different blood Centers. Blood samples from each participant were collected for laboratory analysis and self-rating instruments were administered on the same day. Biological parameters included those usually assessed during blood donation. Individuals were selected based on the criteria for the clinimetric evaluation of AO. Differences in biomarkers between subjects with and without allostatic overload were performed using the GLM with biological measures as dependent variables, AO groups as the fixed factor and specific confounders as covariates. Based on the selection criteria for allostatic overload, 98 subjects have been identified as presenting with AO. Results showed that individuals with allostatic overload presented lower levels of serum proteins, erythrocytes and immune differential count than donors without allostatic overload. Further, greater mean corpuscular volume has been found in persons included in the AO group. The evaluation of the AO correlates, along with a biomarker profile, may help to identify those conditions that, by exceeding individual resources, may constitute a danger to health.