Does Early Trauma Affect Nervous System Function?
Levels of brain-derived neurotrophic factor (BDNF), a neural biomarker involved in neurogenesis and long-term memory formation, do not appear to be altered by exposure to an adverse childhood experience (ACE).
ACEs, which can include physical, sexual, or emotional abuse, or physical and emotional neglect, have been linked to early mortality and risks for chronic diseases and psychiatric diagnoses.
Prior research focused mainly on the impact of ACEs on cortisol levels and inflammatory biomarkers, and less is known about the impact of ACEs on the developing nervous system.
After a literature search, 22 studies were included in the systematic review, 10 of which were included in the meta-analysis.
BDNF protein levels were primarily measured in serum, plasma, and whole blood.
The random-effects meta-analysis showed those with ACE did not have significantly different levels of BDNF protein compared with unexposed individuals (ratio of means [ROM], 1.08; 95% CI, 0.93 – 1.26).
However, BDNF levels were generally elevated in ACE-exposed people in studies investigating childhood maltreatment and in those that measured sera levels.
There was a trend towards higher BDNF protein levels measured in the ACE-exposed group prior to age 20 years.
Individual studies show ACE-dependent changes in BDNF levels, but limited sample sizes and heterogeneous study designs limit reaching a consensus on the strength of the possible relationship, the researchers note.
The review was conducted by Neha Vyas, Duke University, Trinity College of Arts and Sciences, Durham, North Carolina, and colleagues. It was published in Psychoneuroendocrinology.
Several publications that did not provide true mean BDNF values were not included. Study sample sizes were small and there was substantial between-study heterogeneity. Studies used varied definitions of ACE exposure.
The work was supported by the National Institute on Aging of the National Institutes of Health. The authors have reported no relevant financial relationships.
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