Browsing by Subject "depression"

Background: We studied two different visual effects: In brightness induction, the perceived brightness of the stimulus is altered by the luminance of its surround, and in orientation selective contrast suppression the contrast of the stimulus appears lower when surrounded by a collinear surround of higher contrast. In previous studies, orientation selective contrast suppression has been found to be altered in patients who have been diagnosed with depression. Objectives: We measured symptoms of anxiety and depression in our non-clinical sample in order to compare them to their performance in the visual experiments. The goal of our online experiment was also to replicate both of the visual effects without a tightly controlled environment. Methods: Our online experiment consisted of a repeated measures design, with separate blocks for randomised brightness trials, randomised contrast trials, and self-report mental health questionnaires. In the visual trials participants were asked to estimate the brightness or contrast level of a central stimulus, while its surround was varied in luminance or contrast. Our sample consisted of 76 healthy participants with a mean age of 25. Results and conclusions: We managed to replicate both the brightness induction and the orientation selective contrast suppression effects, and found that the use of different electronic devices in completion of the study had no significant effect on the results. Participants reported varying levels of symptoms of anxiety and depression, and 61.6 % of them crossed clinically relevant cut-off points. We did not find a statistically significant connection between the visual effects and symptoms of anxiety and depression. This is encouraging, as it indicates that having only a few symptoms of mental disorders does not alter contrast perception. However, finding out at what point is the contrast perception altered, warrants further study.

Objective: Qualitative studies have suggested depressed people may experience temporal disturbances in time perception, feeling 'stuck in time'. However, behavioral evidence using temporal perception tasks has thus far not found evidence of a relationship between depression and time perception. A recent study suggested time perception is not merely a result of mood and attention but also driven by mental imagery. In the present study, I investigate whether mental imagery and depression separately or interactively affect the perception of time. Methods: 73 participants took part in the study. Prior to the start of the experiment, the participants’ depression was assessed using Beck's Depression Inventory. The participants were then instructed on the verbal time estimation task: they watched a 7, 10 or 16 second video of either a quickly or slowly moving starfield and estimated its duration on a visual scale of 4 to 20 seconds. While watching the video, they were instructed to imagine moving either slow, fast or just to passively watch the video. Each participant performed a total of 36 trials. The experiment used a repeated measures design, and a linear mixed-effects model was used for statistical analysis. Results and conclusion: Differences in BDI scores, measuring depression, did not predict differences in time estimates. Within participants, however, mental imagery strongly affected perceived time: Slow imagery caused temporal underestimation compared to fast and passive viewing. These findings replicated previous work. However, a significant interaction was observed between depression and visual imagery on estimated time: The more depressed the participant was, the more temporal underestimation was observed during slow imagery conditions.

While weeks of continuous treatment is required for conventional antidepressant drugs (e.g. fluoxetine) to bring their full therapeutic effects, a subanesthetic dose of ketamine alleviates the core symptoms of depression (anhedonia, depressed mood) and suicidal thinking within just few hours and the effects may last for days. Nitrous oxide (N2O, “laughing gas”), another NMDAR antagonist, has recently been shown to have similar rapid antidepressant effects in treatment-resistant depressed patients (Nagele et al. 2015). We previously found using naïve mice ketamine and N2O treatment to upregulate five mRNAs related to the MAPK pathway and synaptic plasticity, both implicated as being important in the action of rapid-acting antidepressants. In the current study, these shared mechanisms were further investigated in C57BL/6JHsd mice, using behavioral test batteries to study depressive-like behaviour and RT-qPCR for biochemical analyses. We first aimed to demonstrate behavioral differences between naïve mice and a chronic corticosterone-induced animal model of depression, and to use this model to investigate antidepressant-like effects of ketamine and N2O. According to the results, chronic corticosterone produced some behaviors typical of a depressive-like phenotype, namely significant worsening of coat state and decreased saccharin consumption in the saccharin preference test. Both ketamine and N2O exhibited antidepressant-like effects by reverting decreased saccharin preference. We then aimed to elucidate the effects of ketamine and N2O on five previously found shared mRNAs: Arc, Dusp1, Dusp5, Dusp6 and Nr4a1. N2O significantly upregulated all targets in the vmPFC, except Dusp5, two hours after beginning of N2O treatment. Neither ketamine nor sole chronic corticosterone produced any significant changes. The results of this study suggest that N2O is a potential candidate for rapid alleviation of depressive symptoms. We suggest that the action of rapid-acting antidepressants, more specifically N2O, is based on a homeostatic response of the brain to a presented challenge. Here this challenge would be cortical excitation previously been shown to be caused by N2O, which leads to activation of pathways such as MAPK and subsequent Arc, Dusp and Nr4a1 signaling. The level of expression of these markers would then depend on which phase this response is in and hence, the differences in time between treatment and brain sample dissection could be a reason for conflicting results to previous research. Future studies would benefit from detailed investigation of the chronic corticosterone-induced model due to its potential in controlling for behavioral variability, thus reducing the number of animals needed for preclinical research. Overall the preliminary findings of this study could be one of the first steps in the search for the mechanisms underlying the potential antidepressant effect of N2O, how these molecular markers are related to its action and how it differs from the action of ketamine.

Adolescence is characterized by a substantial rise in the prevalence of depressive disorder. While in adulthood lower socioeconomic position predicts a greater risk of depression, studies have found inconsistent evidence for social differentials in depression in adolescence and early adulthood. Numerous studies have documented that low childhood socioeconomic position predicts a higher risk of later depression, but less research has been conducted to investigate how the individual’s own educational track is associated with depression in adolescence and early adulthood. This thesis investigates whether the risk of depression varies by childhood socioeconomic position and personal educational track. Adopting the life-course perspective, this study examines how childhood socioeconomic position and own educational track combine to predict depression in late adolescence and early adulthood. A social pathway model anticipates that a low childhood socioeconomic position increases the risk of a low personal educational track which in turn increases the risk of later depression. Furthermore, the resource substitution model hypothesizes that the protective effect of a higher educational track is greater for those from more disadvantaged backgrounds substituting for the lacking childhood resources. Gender-specific determinants of depression are also examined. This thesis used annually updated individual-level register data EKSY014, which consisted of a 20-per-cent random sample of 0–14-year-olds living in private households in Finland at the end of year 2000. The study population of this study was restricted to individuals born in 1986–1990 (n=60,829), and they were followed over two educational transitory stages, firstly at age 17–19, and secondly at age 20–23 years. Depression was identified from health care registers maintained by The National Institute for Health and Welfare and The Social Insurance Institution of Finland. Survival analysis using Cox proportional hazards models was conducted to estimate the relative and combined effects of childhood socioeconomic position and educational track on the hazard of depression. According to the results, both low childhood socioeconomic position and lower personal educational track are associated with an increased risk of depression in late adolescence and early adulthood. School discontinuation and prolonged upper secondary schooling and also a vocational track among women predict a greater risk of depression compared to academic track. Educational track mediates the association between low childhood socioeconomic position and the risk of depression but is also independently associated with the risk. Early mental disorders also play a significant role in the process by influencing post-comprehensive tracking. The results further suggest that a higher educational track does not provide as effective protection against depression for 17–19-year-old adolescents if the individual lacks familial resources, but is more important for adolescents with higher socioeconomic backgrounds. Educational track does not moderate the effect of childhood socioeconomic position on depression among 20–23-year-olds. The results of this study fit in with the pathway conceptualization of the life-course approach. Educational track constitutes a social pathway mediating the effect of low childhood socioeconomic position on the risk of depression in adolescence and early adulthood. However, not all differences in risk by educational track are explained by childhood socioeconomic position but a lower educational track poses a risk on mental health independent of childhood resources. The findings do not support the resource substitution hypothesis among adolescents and young adults. In total, the findings demonstrate that early segregation of educational trajectories comes with differential chances for mental health.

Aims. Attachment has been linked to children's psychiatric symptoms. However, only a few studies have focused on parental attachment towards the child. Most studies have focused on parent's general attachment representations, which do not address the parental subjective attachment to their child. The aim of this study is to examine whether parental subjective attachment towards the child is associated with child's internalizing and externalizing symptoms and total problems. We also examine whether maternal or paternal depression, child temperament or gender affect the aforementioned associations. Methods. This study is a part of Prediction and Prevention of Pre-eclampsia (PREDO) – study. The size of the current study sample was 2021 mothers and 1273 fathers and their children. Maternal and paternal attachment were assessed with the Maternal/Paternal Postnatal Attachment Scale (MPAS/PPAS) – self report questionnaire when the child was six months old. Child's internalizing, externalizing and total problems were assessed with the Child Behavior Checklist 1½-5 (CBCL1½-5) – questionnaire when the child was 1.5 to 5 years old. The associations were investigated using linear regression analysis, controlling for maternal or paternal attachment and several sociodemographic factors related to the child and parents. Results and conclusions. Results indicated that secure maternal and paternal attachment was associated with less internalizing, externalizing and total problems in children. Parental depression and child's temperamental traits mediated the association of parental attachment and child's psychiatric symptoms. Maternal attachment was also independently associated with child's psychiatric symptoms. An interaction effect was found between maternal attachment and child's negative emotionality in relation to child's total problems: insecure maternal attachment and child's high negative emotionality were associated with more total problems in childhood. These results provide evidence that both parents' subjective attachment is related to child's psychiatric symptoms, and also highlight the significance of child's temperament in the development of psychiatric symptoms.