The late positive potential (LPP): A neural marker of internalizing problems in early childhood

Background
One potentially relevant neurophysiological marker of internalizing problems (anxiety/depressive symptoms) is the late positive potential (LPP), as it is related to processing of emotional stimuli. For the first time, to our knowledge, we investigated the value of the LPP as a neurophysiological marker for internalizing problems and specific anxiety and depressive symptoms, at preschool age.

Method
At age 4 years, children (N = 84) passively viewed a series of neutral, pleasant, and unpleasant pictures selected from the International Affective Pictures System. Affective picture processing was measured via the LPP (EEG recorded) and mothers reported on child behavior via the Child Behavior Checklist 1 ½ - 5 (internalizing, DSM-anxiety, DSM-affective/depression subscales). Difference scores between the neutral and affective pictures (i.e., neutral-pleasant and neutral-unpleasant) were computed for posterior, central and anterior brain locations for early (300-700 ms), middle (700-1200 ms) and late (1200-2000 ms) time windows.

Results
Greater LPP difference scores for pleasant images in the anterior recording site, in the middle time window, were associated with greater internalizing behaviors. Greater DSM-anxiety symptoms were associated with greater LPP difference scores for unpleasant and pleasant images. After correcting for multiple testing, only the association between greater DSM-affective/depression symptoms and greater LPP difference scores for unpleasant images in the anterior recording site (early time window) remained significant.

Discussion
Our study has identified a potential neural marker of preschool internalizing problems. Children with larger LPPs to unpleasant images may be at greater risk of internalizing problems, potentially due to an increased emotional reactivity.