Affect-modulated startle reflex and dopamine D4 receptor gene variation.

Area of Science:

• Neuroscience
• Behavioral Genetics
• Psychophysiology

Background:

• The affect-modulated acoustic startle response (ASR) is a potential indicator of emotional reactivity.
• Emotional reactivity is considered an endophenotype, linking genetic predispositions to observable traits.
• The dopamine D4 receptor (DRD4) gene polymorphism is implicated in various behavioral and emotional processes.

Purpose of the Study:

• To investigate the association between the DRD4 polymorphism and affect-modulated ASR in healthy volunteers.
• To determine if the presence of the DRD4 7R allele influences emotional reactivity as measured by ASR.

Main Methods:

• 114 healthy participants were categorized into DRD4 7R allele carriers (7R group) and non-carriers (7R-absent group).
• Affect-modulated ASR was measured, assessing startle potentiation and inhibition across different emotional stimuli.
• Exploratory analysis examined associations with 5-HTT, COMT, and DAT polymorphisms.

Main Results:

• The 7R-absent group exhibited a typical affect-modulated ASR.
• The 7R group displayed a blunted affect-modulated ASR, characterized by reduced startle potentiation to unpleasant stimuli.
• No significant associations were found between affect-modulated ASR and the exploratory polymorphisms (5-HTT, COMT, DAT).

Conclusions:

• The DRD4 polymorphism significantly modulates emotional responses, particularly in the context of startle reactivity.
• Affect-modulated ASR serves as a valuable endophenotype for studying the genetic underpinnings of emotional reactivity.
• Findings highlight the role of DRD4 in emotional processing and its utility in genetic research.