Plasma and cerebrospinal fluid inflammatory markers and human aggression

Area of Science:

• Neuroscience
• Psychiatry
• Immunology

Background:

• Chronic, low-level inflammation, indicated by elevated pro-inflammatory cytokines and acute phase proteins, is linked to aggressive behavior.
• Animal studies show direct brain application of pro-inflammatory proteins increases aggression, but human data on central inflammatory markers and aggression is lacking.

Purpose of the Study:

• To investigate the relationship between plasma and cerebrospinal fluid (CSF) pro-inflammatory markers and aggression in humans.
• To compare inflammatory marker levels in individuals with and without Intermittent Explosive Disorder (IED).

Main Methods:

• Simultaneously measured plasma and CSF levels of C-Reactive Protein (CRP), IL-6, IL-8, and TNF-α in 77 healthy, drug-free individuals.
• Assessed aggression using the Life History of Aggression (LHA) and Buss-Perry Aggression Questionnaire (BPAQ).
• Included 22 individuals diagnosed with DSM-5 Intermittent Explosive Disorder (IED).

Main Results:

• Plasma and CSF levels of CRP, IL-8, and TNF-α correlated significantly, but IL-6 did not.
• Individuals with IED showed elevated plasma, but not CSF, pro-inflammatory markers.
• Composite aggression scores correlated significantly with plasma, but not CSF, pro-inflammatory markers.

Conclusions:

• Aggressive behavior in humans is associated with peripheral (plasma) pro-inflammatory markers, not central (CSF) markers.
• Pro-inflammatory proteins may influence brain-based aggression through mechanisms not reflected in lumbar CSF.
• Findings highlight a dissociation between peripheral inflammation and central inflammatory markers in relation to human aggression.