Background Oxidative stress is implicated in both depression and anxiety, but it is currently unclear whether this relates to syndromal diagnoses or trans-diagnostic dimensional symptoms. We examined the relationship between oxidative stress and severity of depression and anxiety symptoms in individuals with Major Depressive Disorder (MDD). Methods Plasma oxidative stress markers F2-isoprostanes and oxidized glutathione (GSSG), and the antioxidant reduced glutathione (GSH), were assessed in 69 physically healthy, medication-free MDD subjects. Symptoms of anxiety and depression were assessed using the Hamilton Anxiety (HAM-A) and Hamilton Depression (HAM-D) Rating Scales. Total HAM-A and HAM-D scores, along with “core” anxiety and depression subscales, and individual HAM-D items “psychic anxiety” and “depressed mood,” were related to oxidative stress markers. Analyses controlled for age, sex, BMI, and smoking. Results Total HAM-A ratings were positively associated with F2-isoprostanes (β=.26, p=0.042) and GSSG (β=.25, p=0.049), but not GSH (β=.05, p=0.711). Core anxiety severity was positively associated with F2-isoprostanes (β=.34, p=0.012) and GSSG, although this did not reach significance (β=.24, p=0.074). None of the biological markers were significantly associated with total HAM-D or core depression ratings (all p>0.13). Subjects scoring high on “psychic anxiety” had elevated F2-isoprostanes (p=0.030) and GSSG (p=0.020). This was not seen with “depressed mood” scores (all p>0.12). Limitations We assessed peripheral oxidative markers, but their relationship to the brain is unclear. Conclusions Oxidative stress is more closely related to anxiety than depression symptoms in MDD. This highlights the importance of relating oxidative stress to specific symptoms and could provide new insights into the biological correlates of affective disorders.

Background: Psychotic experiences are common in childhood and an important risk indicator of adverse mental health outcomes. However, little is known about the association of psychotic experiences with functional outcomes in childhood, particularly regarding school performance. The aim of the present study was to examine whether psychotic experiences were prospectively related to school performance in childhood. Methods: This study was embedded in the population-based Generation R Study (N = 2,362). Psychotic experiences were assessed using selfreports on hallucinations at age 10 years. School performance was assessed using a standardized national school performance test at age 12 years. We considered the total school performance score, as well as language and mathematics subscales. Analyses were adjusted for sociodemographic characteristics, maternal nonverbal IQ, nonverbal IQ at age 6 years and co-occurring psychopathology at age 10 years. Results: Psychotic experiences were prospectively associated with poorer school performance scores (B = À0.61, 95% CI [À0.98;À0.25], p = .001), as well as poorer language (B percentile rank score = À2.00, 95% CI [À3.20;À0.79], p = .001) and mathematical ability (B percentile rank score = À1.75, 95% CI [À2.99;À0.51], p = .006). These associations remained after additional adjustment for nonverbal IQ at age 6 years (B = À0.51, 95% CI [À0.86;À0.16], p = .005), and co-occurring internalizing (B = À0.40, 95% CI [À0.77;À0.03], p = .036) and externalizing problems (B = À0.40, 95% CI [À0.75;À0.04], p = .029), but not attention problems (B = À0.10, 95% CI [À0.47;0.26], p = .57). Conclusions: Children with psychotic experiences had lower school performance scores than their nonaffected peers. The finding was independent of sociodemographic characteristics, intelligence and co-occurring internalizing and externalizing problems, but not attention problems. This study suggests that psychotic experiences are associated with childhood functional impairments, although the relatively small effects and the role of attention problems warrant further exploration.

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