EEG-responses to mood induction interact with seasonality and age

Abstract

The EEG is suggested as a potential diagnostic and prognostic biomarker for seasonal affective disorder (SAD). As a pre-clinical form of SAD, seasonality is operationalized as seasonal variation in mood, appetite, weight, sleep, energy, and socializing. Importantly, both EEG biomarkers and seasonality interact with age. Inducing sad mood to assess cognitive vulnerability was suggested to improve the predictive value of summer assessments for winter depression. However, no EEG studies have been conducted on induced sad mood in relation to seasonality, and no studies so far have controlled for age. We recorded EEG and calculated bandpower in 114 participants during rest and during induced sad mood in summer. Participants were grouped by age and based on a seasonality score as obtained with the seasonal pattern assessment questionnaire (SPAQ). Participants with high seasonality scores showed significantly larger changes in EEG power from rest to sad mood induction, specifically in the alpha frequency range (p = 0.027), compared to participants with low seasonality scores. Furthermore, seasonality interacted significantly with age (p < 0.001), with lower activity in individuals with high seasonality scores that were older than 50 years but the opposite pattern in individuals up to 50 years. Effects of sad mood induction on brain activity are related to seasonality and can therefore be consider as potential predicting biomarkers for SAD. Future studies should control for age as a confounding factor, and more studies are needed to elaborate on the characteristics of EEG biomarkers in participants above 50 years.

Emotional Bias among Individuals at Risk for Seasonal Affective Disorder—An EEG Study during Remission in Summer

“…To this end, we first grouped individuals into a younger group of up to 50 years and an older group of 50 years and older. This grouping is in line with a previous publication that showed that EEG responses in relation to seasonality interact with age [60]. According to this grouping, only three participants ended up in the group that scored high on seasonality and was older than 50 years.…”

“…Young people and evening chronotypes are especially susceptible to experiencing winter depression [98], and there is evidence for differential effects of seasonality on EEG responses to mood induction [60]. In our sample, individuals with increased levels of seasonality were significantly younger than individuals with lower levels of seasonality.…”

“…The EEG is also a commonly used biomarker in research on depression [59]. EEG research is much less established in SAD, but EEG biomarkers were successfully used in research on seasonality [60,61]. Lower power in most frequency bands as well as frontal asymmetrical activity was reported for participants with seasonality [48].…”

Seasonal Affective Disorder: A Narrative Review

“…In a study entitled "EEG responses to mood induction interact with seasonality and age", EEG was recorded during rest and during induced mood in the summertime (N=114) [34]. Seasonality in this study was defined as a pre-clinical form of SAD including seasonal variation in mood, appetite, weight, sleep, energy, and socializing.…”

“…In a different paper published by the same research group entitled "Predictability of seasonal mood fluctuations based on self-report questionnaires and EEG biomarkers in a nonclinical sample", several questionnaires were given [34]. The questionnaire data had 82% accuracy of predicting seasonality as did the EEG alone data.…”