Negative mood is associated with decreased prefrontal cortex functioning during working memory in young adults

The prefrontal‐subcortical model of emotion regulation postulates that decreased prefrontal cortex (PFC) functioning may underlie the emergence of clinical affective disorders. In addition, accumulated evidence suggests that there is considerable variability in negative affect in the nonclinical population. This study examined whether negative affective symptoms were associated with decreased PFC functioning in nonclinical young adults. Forty college students aged 18–24 years (ten males) underwent an n‐back paradigm (i.e., a frontal executive task) with a working memory (WM) load (i.e., 3‐back) and a vigilance control condition (i.e., 0‐back) while their hemodynamics changes in the lateral and medial PFC on both sides were monitored using a 16‐channel functional near‐infrared spectroscopy (fNIRS) system. They also filled out the Depression Anxiety Stress Scales (DASS) to estimate the levels of their negative emotions in the preceding week. Young adults exhibited an increased concentration of oxyhemoglobin and a decreased concentration of deoxyhemoglobin (i.e., activation), primarily in the lateral PFC, in response to the WM load (i.e., 3‐back > 0‐back). Importantly, higher DASS scores indicating higher levels of recent negative mood, especially depression and stress rather than anxiety symptoms, correlated with lower WM‐related activation in the lateral PFC. Thus, recent negative mood is associated with decreased lateral PFC functioning during the executive control of WM in healthy young adults. Our findings suggest that decreased PFC functioning is also present in the nonclinical population with increased levels of negative mood and that fNIRS is a promising tool for elucidating individual differences in negative affective symptoms. This work extends previous neuroimaging work in affective disorders by using functional near‐infrared spectroscopy (fNIRS) to show that decreased prefrontal cortex functioning relates to recent negative mood in a nonclinical population. It thus promotes the application of fNIRS for the neuroscientific study of individual differences in negative affective symptoms. Our findings of monotonic relationships between negative mood and decreased prefrontal cortex functioning are consistent with the dimensional constructs of depression and stress symptoms.