The antidepressant effect of whole-body hyperthermia is associated with the classical interleukin-6 signaling pathway.

There is urgent need for novel antidepressant treatments that confer therapeutic benefits via engagement with identified mechanistic targets. The objective of the study was to determine whether activation of the classical anti-inflammatory interleukin-6 signaling pathways is associated with the antidepressant effects of whole-body hyperthermia. A 6-week, randomized, double-blind study compared whole-body hyperthermia with a sham condition in a university-based medical center. Medically healthy participants aged 18-65 years who met criteria for major depressive disorder, were free of psychotropic medication use, and had a baseline 17-item Hamilton Depression Rating Scale score ≥ 16 were randomized with 1-to-1 allocation in blocks of 6 to receive whole-body hyperthermia or sham. Of 338 individuals screened, 34 were randomized, 30 received interventions and 26 had ≥ 2 blood draws and depressive symptom assessments. Secondary data analysis examined change in the ratio of IL-6:soluble IL-6 receptor pre-intervention, post-intervention, and at weeks 1 and 4. Hierarchical linear modeling tested whether increased IL-6:soluble IL-6 receptor ratio post-intervention was associated with decreased depressive symptom at weeks 1, 2, 4 and 6 for those randomized to whole-body hyperthermia. Twenty-six individuals were randomized to whole-body hyperthermia [n = 12; 75 % female; age = 37.9 years (SD = 15.3) or sham [n = 14; 57.1 % female; age = 41.1 years (SD = 12.5). When compared to the sham condition, active whole-body hyperthermia only increased the IL-6:soluble IL-6 receptor ratio post-treatment [F(3,72) = 11.73,p < .001], but not pre-intervention or at weeks 1 and 4. Using hierarchical linear modeling, increased IL-6:sIL-6R ratio following whole-body hyperthermia moderated depressive symptoms at weeks 1, 2, 4 and 6, such that increases in the IL-6:soluble IL-6 receptor ratio were associated with decreased depressive symptoms at weeks 1, 2, 4 and 6 for those receiving the active whole-body hyperthermia compared to sham treatment (B = -229.44, t = -3.82,p < .001). Acute activation of classical intereukin-6 signaling might emerge as a heretofore unrecognized novel mechanism that could be harnessed to expand the antidepressant armamentarium.

Concurrent and prospective associations of inflammatory signaling, specific depressive symptoms, and substance use in adolescence.

Substance use and depression frequently co-occur. Adolescence appears to be a vulnerable developmental period for increases in both substance use and depressive symptoms, often attributed to rapid maturation of reward and motivation systems. Another contributing factor could be inflammatory signaling, which has been associated with both substance use disorder and depression. Prior research indicates that an increase in inflammatory activity can cause physical and emotional malaise, which resembles depression, and the anhedonia and somatic symptoms could lead to substance use. This perspective that substance use is a type of self-medication in response to anhedonia and subjective experiencing of increased inflammatory physiology has not been investigated previously. To test these associations, we used path analysis to examine concurrent and prospective associations between three pro-inflammatory markers, specific depressive symptoms, and substance use frequency in a diverse sample of older adolescents. Participants completed repeated self-report measures of specific depressive symptoms (i.e., dysphoria, anhedonia, somatic concerns, negative cognitions, and functional difficulties) and substance use frequency. Blood was collected to quantify circulating levels of interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP). This analysis showed an indirect effect of IL-6 and TNF-α levels on future substance use, but only via functional difficulties. Substance use also predicted future functional difficulties. Only anhedonia directly predicted future substance use frequency. These findings help to more precisely identify pathways through which inflammatory physiology and specific depressive symptoms synergistically confer risk for substance use.

Examining inflammation, health, stress and lifestyle variables linking low socioeconomic status with poorer cognitive functioning during adolescence.

Higher C-reactive protein (CRP) is associated with cognitive difficulties. The nature of this association remains unclear given that multiple other variables are linked with both CRP and cognitive difficulties, which may confound the association. The goal of the current study is to determine whether low socioeconomic status (SES) is associated with worse cognitive functioning via higher CRP and whether this association is independent of known associations with other health, stress and lifestyle factors (e.g., depression, physical activity, body mass). Assessments in a longitudinal study of 1,029 Dutch adolescents were based on a combination of self-report and parent-report questionnaires, diagnostic assessment, behavioral testing, and blood assay. We estimated latent variables for cognitive functioning (executive functioning, verbal fluency, episodic memory) and used structural equation analysis to test whether SES (wave 1: 11.08 years (SD=0.55); 55% female] was associated with worse cognitive outcomes (wave 4: aged 18.97 years; SD=0.55) via increased CRP, depression, stress, body mass, substance use or physical inactivity (wave 3: aged 16.17 years; SD=0.61). Low SES was associated with worse cognitive functioning via increased CRP. Additionally, low SES was associated with (i) worse executive functioning via higher body mass, higher levels of sedentary behavior, and higher stress, (ii) worse verbal fluency via higher levels of sedentary behavior and (iii) worse episodic memory via sedentary behaviors, body mass, and substance use. These results confirm the link between SES, CRP and cognitive functioning and additionally identify four modifiable lifestyle factors that may be implicated in the link between low SES and worse performance on tests of cognitive functioning.

The longitudinal associations of inflammatory biomarkers and depression revisited: systematic review, meta-analysis, and meta-regression.

The innate immune system is dysregulated in depression; however, less is known about the longitudinal associations of depression and inflammatory biomarkers. We investigated the prospective associations of depression and inflammatory biomarkers [interleukin-6 (IL-6), Tumor Necrosis Factor-Alpha (TNF-α), and C-reactive protein (CRP)] in community samples, both unadjusted and adjusted for covariates. The review, registered with PROSPERO, searched for published and unpublished studies via MEDLINE/PsycINFO/PsycARTICLES/EMBASE/Proquest Dissertation. Standardized Fisher transformations of the correlation/beta coefficients, both unadjusted and adjusted for covariates, were extracted from studies examining the prospective associations of depression and inflammatory biomarkers. Systematic review conducted in January, 2019 included 38 studies representing 58,256 participants, with up to 27 studies included in random-effects meta-analysis. Higher CRP/IL-6 were associated with future depressive symptoms, and higher depressive symptoms were associated with higher future CRP/IL-6 in both unadjusted and adjusted analyses - this is the first meta-analysis reporting an adjusted association of IL-6 with future depression. The adjusted prospective associations of depression with CRP/CRP with depression were substantially attenuated and small in magnitude. No significant associations were observed for TNF-α. No conclusive results were observed in studies of clinical depression. Meta-regression indicated that the association of CRP and future depression was larger in older samples and in studies not controlling for possible infection. Small, prospective associations of depression and inflammatory biomarkers are observed in both directions, particularly for IL-6; however, the strength and importance of this relationship is likely obscured by the heterogeneity in depression and profound study/methodological differences. Implications for future studies are discussed.

Investigating whether depressed youth exhibiting elevated C reactive protein perform worse on measures of executive functioning, verbal fluency and episodic memory in a large, population based sample of Dutch adolescents.

Cognitive functioning is disrupted during a depressive episode and cognitive dysfunction persists when depression is in remission. A subtype of depressed individuals who exhibit elevated inflammatory biomarkers may be at particular risk for cognitive dysfunction. We examined whether an elevated inflammatory biomarker (C-reactive protein: CRP) in acute and/or remitted depression was associated with specific deficits in executive functioning, episodic memory, and verbal fluency. Data were drawn from a population-based sample of Dutch adolescents (N = 1066; 46% male) recruited at the age of 11 and followed over the course of eight years. We tested whether adolescents with either, (i) a history of depression (Wave 1-3) or (ii) current depression (Wave 4), and elevated levels of C-reactive protein measured in blood at Wave 3 performed worse on cognitive assessments at Wave 4. Eight measures of cognitive functioning were hypothesized to load on to one of three dimensions of cognitive functioning (executive functioning, episodic memory, and verbal fluency) within a structural equation model framework. Higher levels of CRP were associated with worse future executive functioning in adolescents with and without current/prior depression. A current depression diagnosis also was associated with worse executive functioning. There was consistent evidence linking low socioeconomic status and health-related covariates (high body mass index/sedentary behavior) with worse performance across multiple measures of cognitive functioning and, importantly, the association of depression/CRP and executive functioning was no longer significant when controlling for these covariates. Future studies may benefit from investigating whether specific depressogenic behaviors (e.g., sedentary behavior/substance use) mediate a relationship between depression and worse executive functioning, potentially via a prospective pathway through elevated inflammation.

Investigating whether a combination of higher CRP and depression is differentially associated with worse executive functioning in a cohort of 43,896 adults.

Many depressed individuals experience difficulties in executive functioning that contribute substantially to functional impairment. It is unknown whether a subtype of depression characterized by chronic inflammation is differentially associated with worse executive functioning. This study examined whether the combination of depression and higher C reactive protein (CRP) is differentially associated with worse executive functioning and whether this association is stronger in older adults. This cross-sectional study analyzed data collected from a population-representative sample of 43,896 adults aged 44.13 years (SD = 13.52) who participated in the baseline assessment of the Lifelines cohort study. Multivariate regression models tested whether depressed individuals (established via structured interview) exhibiting higher levels of inflammation (indexed via high-sensitivity CRP assay following an overnight fast) performed worse on a behavioral test of executive functioning. Depression (B = -3.66, 95% CI: -4.82, -2.49, p < .001) and higher log-transformed CRP (B = -0.67, 95% CI: -0.87,-0.47, p < .001) were associated with worse executive functioning, after adjustment for age, sex, educational attainment, body mass index, smoking status, exposure to stressful life events and chronic stressors, sedentary behavior, and number of chronic medical conditions. Depressed individuals with higher log-transformed CRP exhibited differentially poorer executive functioning (B = -1.09, 95% CI: -2.07,-0.11, p < .001). This association did not differ based on age (B = 0.01, 95% CI: -0.08, 0.10, p = .82). Executive functioning is poorer in depressed individuals with higher CRP, even in early adulthood. Interventions that reduce inflammation may improve cognitive functioning in depression.

Goal-striving tendencies moderate the relationship between reward-related brain function and peripheral inflammation.

Inflammation is associated with both lower and higher activity in brain regions that process rewarding stimuli. How can both low and high sensitivity to rewards be associated with higher inflammation? We propose that one potential mechanism underlying these apparently conflicting findings pertains to how people pursue goals in their environment. This prediction is based on evidence that both an inability to disengage from unattainable goals and low interest in and pursuit of important life goals are associated with poor health outcomes, including inflammation. Accordingly, this study examined the relationship between reward-related brain function and peripheral inflammation among individuals with different levels of ambitious goal-striving tendencies. Eighty-three participants completed an ambitious goal-striving tendency measure, an fMRI Monetary Incentive Delay task assessing orbitofrontal cortex (OFC) and nucleus accumbens (NAc) activation during reward anticipation and outcome, and a venous blood draw to assess the inflammatory biomarkers interleukin (IL)-6, IL-8, tumor necrosis factor-alpha, and C-reactive protein, from which we computed an inflammation composite score. We observed a reward anticipation by goal-striving interaction on inflammation, such that high OFC and NAc activation to reward anticipation (but not outcome) were associated with more inflammation, among high goal-striving individuals. By contrast, low NAc activation during reward anticipation (but not outcome) was associated with more inflammation, among low goal-striving individuals. The current study provides further evidence that both blunted and elevated reward function can be associated with inflammation. It also highlights the role that goal-striving tendencies may play in moderating the relationship between neural reward anticipation and inflammation.

Negative Inferential Style Mediates the Association between Racial Identity and Depressive Symptoms among African American Adolescents.

Negative inferential style is a cognitive vulnerability for depression. Yet, few studies have explored how this risk factor intersects with culturally-specific protective factors, such as racial identity, in a unified cognitive risk-cultural asset model in youth of color. The current study addressed this gap by exploring the interplay between negative inferential style, racial identity, and depressive symptoms in an urban African-American adolescent community sample (N = 233; 51.9% female). Cross-lagged panel analyses estimated concurrent and prospective relationships between study variables. Racial identity dimensions of regard, but not centrality, were significant predictors of inferential style, and buffered against the development of depressive symptoms via the development of a less negative inferential style. Implications for the study of racial identity and cognition, and treatment of African-American adolescents are discussed.

Concurrent and Longitudinal Associations of Sex and Race with Inflammatory Biomarkers during Adolescence.

Chronic, systemic inflammation is implicated in physical and mental health; little is known about whether sex and racial differences detected in adulthood are observed during adolescence or about normative changes occurring during adolescence. This longitudinal, United States-based study examined four biomarkers of systemic inflammation [C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and IL-8) in 315 adolescents (51% female; 58% black; baseline age = 16.49 years (SD = 1.56; range: 12.14-21.28)] at three timepoints. Notable results included: general decline in inflammatory biomarkers in older adolescents, lower levels of TNF-α/IL-8 in black adolescents, elevated CRP/IL-6 in females, and especially higher levels of IL-6 in black, female adolescents. Implications are discussed, particularly the potential health implications of elevated IL-6 in black females.

Executive dysfunction in depression in adolescence: the role of inflammation and higher body mass.

BACKGROUND: There is substantial evidence that many depressed individuals experience impaired executive functioning. Understanding the causes of executive dysfunction in depression is clinically important because cognitive impairment is a substantial contributor to functional impairment. This study investigated whether elevated levels of an inflammatory cytokine [interleukin-6 (IL-6)] and/or higher body mass index (BMI) concurrently and/or prospectively accounted for the relationship between depressive symptoms and impaired executive functioning in adolescents. METHODS: A diverse, community sample of adolescents (N = 288; mean age = 16.33; 51.4% female; 59.0% African-American) completed assessments of height and weight, IL-6, depressive symptoms, and self-report/behavioral measures of executive functioning (selective attention, switching attention) and future orientation annually over 3 years. Adolescents experiencing acute illness or medical conditions that affect inflammation were excluded from analyses. Path analysis within a structural equation modeling framework simultaneously examined the concurrent and prospective relationships between BMI, IL-6, depressive symptoms, and the measures of cognitive functioning across three timepoints. RESULTS: Across all timepoints, higher BMI was prospectively associated with higher levels of IL-6 and depressive symptoms, while higher levels of IL-6 were associated with worse performance on three behavioral and self-report measures of cognitive functioning. Higher depressive symptoms also were prospectively associated with elevated IL-6 and both higher depressive symptoms and a higher BMI predicted worse future executive functioning via increased IL-6. CONCLUSIONS: More severe depressive symptoms and increased BMI may disrupt executive functioning via elevated IL-6.

Longitudinal changes of inflammatory biomarkers moderate the relationship between recent stressful life events and prospective symptoms of depression in a diverse sample of urban adolescents.

This study investigated whether longitudinal changes in inflammatory physiology moderated the relationship between recent stressful life events and subsequent depressive symptoms in adolescence. A diverse sample of adolescents representative of an urban community (N = 129; Age at baseline = 12.5 years; 48.8% female; 55.0% African American) completed measures of stressful life events, depressive symptoms, and two annual blood draws (BD1 and BD2). Controlling for inflammatory activity at BD1, depression at BD1, demographics and the time between assessments, increases in interleukin-6 (IL-6; b = 0.878, p = .007) and C-reactive protein (CRP; b = 0.252, p = .024) from BD1 to BD2 interacted with recent stressful life events before BD1 to predict severity of depressive symptoms at BD2. Similar associations were evident for IL-6 (b = 2.074, p = .040) and CRP (b = 0.919, p = .050) when considering acute stressful life events that had occurred within the two weeks before the first blood collection. More frequent stressful life events before BD1 predicted significantly more severe depressive symptoms at BD2, but only for adolescents with moderate (50th percentile) and high (84th percentile) levels of IL-6 and CRP at BD2. In conclusion, adolescents who experienced both recent stressful life events and larger increases in inflammatory activity following these stressors were at increased risk for more severe depressive symptoms after approximately one year. The findings indicate that the interaction of stress and larger changes in inflammatory activity following these stressors are prognostic risk factors for depression severity in adolescents.

Early Pubertal Timing Mediates the Association between Low Socioeconomic Status and Poor Attention and Executive Functioning in a Diverse Community Sample of Adolescents.

Low socioeconomic status (SES) may be associated with earlier pubertal timing and impaired attention and executive function (EF) in youth; however, whether pubertal timing mediates the relation between SES and attention or executive functioning remains unclear. Structural equation models tested concurrent and prospective relations between SES, pubertal timing, and attention and executive functioning measures in a gender and racially diverse sample of adolescents (N = 281, 45.6% male, 50.5% White/Caucasian, 46.3% Black/African American, 3.2% Biracial/other, and 44.5% low SES; complete data were not available on some measures). Youth from low SES families experienced earlier pubertal timing, and this accelerated development was associated with worse performance on attention and executive functioning tasks, both concurrently and longitudinally. These findings highlight a pathway by which youth from low socioeconomic backgrounds may develop worse attention and executive functioning abilities during adolescence.

Unique and predictive relationships between components of cognitive vulnerability and symptoms of depression.

BACKGROUND: Cognitive vulnerability theories of depression outline multiple, distinct inferential biases constitutive of cognitive vulnerability to depression. These include attributing negative events to internal, stable, and global factors, assuming that negative events will lead to further negative consequences, and inferring that negative events reflect negative characteristics about the self. Extant research has insufficiently examined these biases as distinct, limiting our understanding of how the individual cognitive vulnerability components interrelate and confer risk for depression symptoms. Thus, we conducted exploratory network analyses to examine the relationships among the five components of negative cognitive style and explore how components may differentially relate to depressive symptoms in adolescents. METHODS: Participants completed measures of negative cognitive style twice over a two-year period. We estimated Graphical Gaussian Models using contemporaneous data and computed a cross-lagged panel network using temporal data from baseline and 2-year follow-up. RESULTS: Results reveal interesting structural dynamics among facets of negative cognitive style and depressive symptoms. For example, results point to biases towards stable and future-oriented inferences as highly influential among negative cognitive style components. The temporal model revealed the internal attributions component to be heavily influenced by depressive symptoms among adolescents, whereas stable and global attributions most influenced future symptoms. CONCLUSIONS: This study presents novel approaches for investigating cognitive style and depression. From this perspective, perhaps more precise predictions can be made about how cognitive risk factors will lead to the development or worsening of psychopathology.

The Development of Future Orientation is Associated with Faster Decline in Hopelessness during Adolescence.

Hopelessness is implicated in multiple psychological disorders. Little is known, however, about the trajectory of hopelessness during adolescence or how emergent future orientation may influence its trajectory. Parallel process latent growth curve modelling tested whether (i) trajectories of future orientation and hopelessness and (ii) within-individual change in future orientation and hopelessness were related. The study was comprised of 472 adolescents [52% female, 47% Caucasian, 47% received free lunch] recruited at ages 12-13 who completed measures of future orientation and hopelessness at five annual assessments. The results indicate that a general decline in hopelessness across adolescence occurs quicker for those experiencing faster development of future orientation, when controlling for age, sex, low socio-economic status in addition to stressful life events in childhood and adolescence. Stressful childhood life events were associated with worse future orientation at baseline and negative life events experienced during adolescence were associated with both an increase in the trajectory of hopelessness as well as a decrease in the trajectory of future orientation. This study provides compelling evidence that the development of future orientation during adolescence is associated with a faster decline in hopelessness.

Longitudinal Measurement Invariance of the ASEBA Youth/Adult Self-Reports Across the Transition From Adolescence to Adulthood.

The ability to quantify within-person changes in mental health is central to the mission of clinical psychology. Typically, this is done using total or mean scores on symptom measures; however, this approach assumes that measures quantify the same construct, the same way, each time the measure is completed. Without this quality, termed longitudinal measurement invariance, an observed difference between timepoints might be partially attributable to changing measurement properties rather than changes in comparable symptom measurements. This concern is amplified in research using different forms of a measure across developmental periods due to potential differences in reporting styles, item-wording, and developmental context. This study provides the strongest support for the longitudinal measurement invariance of the Anxiety Scale, Depression/Affective Problems: Cognitive Subscale, and the Attention Deficit Hyperactivity Disorder (ADHD) Scale; moderate support for the Depression/Affective Problems Scale and the Somatic Scale, and poor support for the Depression/Affective Problems: Somatic Symptoms Subscale of the Dutch Achenbach System of Empirically Based Assessment Youth Self-Report and Adult Self-Report in a sample of 1,309 individuals (N = 1,090 population-based, N = 219 clinic-based/referred to an outpatient clinic before age 11 years) across six waves of data (mean ages = 11 years at Wave 1 and 26 years at Wave 6).

Chronic inflammation is associated with worsening working memory performance: Preliminary evidence from a diverse, longitudinal cohort of adolescents and young adults.

Many depressed individuals experience cognitive difficulties that persist when depression is in remission. Inflammation is hypothesized to play a role in cognitive dysfunction in depression; however, many aspects of this relationship are not well characterized. The current study examined whether inflammation is associated with specific cognitive deficits in individuals with a history of depression and with progressively worsening working memory over time. Adolescents who participated in a prospective, longitudinal study of adolescent-onset depression were recruited to complete a follow-up cognitive assessment. The sample was comprised of 82 participants (52.4% female; 37.8% white; 42.7% low socioeconomic status) who were aged 22.61 years (SD = 1.50) at the time of the follow-up cognitive assessment. Prior to the follow-up cognitive assessment, they had completed an average of 6.24 (SD = 1.80) prior annual assessments over 6.24 years (SD = 2.08) as part of the parent longitudinal study in which C-reactive protein (CRP), depressive symptoms, and working memory were assessed repeatedly. First, using linear regression, we tested whether individuals exhibiting inflammation (CRP ≥3 mg/L) at multiple timepoints and a history of likely depression (Children's Depression Inventory ≥19) exhibited differentially worse executive functioning, episodic memory, or psychomotor speed. Second, using hierarchical linear modeling, we tested whether the combination of inflammation and likely past depression was associated with poorer working memory over time. Chronic inflammation was associated with worsening working memory over time, but no significant associations were observed in cross-sectional analyses. These preliminary data indicate that chronic inflammation may lead to progressive decline in working memory over time.

Sex-Specific Pathways From Prenatal Maternal Inflammation to Adolescent Depressive Symptoms.

Importance: Prenatal maternal inflammation has been associated with major depressive disorder in offspring in adulthood as well as with internalizing and externalizing symptoms in childhood; however, the association between prenatal inflammation and offspring depression in adolescence has yet to be examined. Objective: To determine whether maternal levels of inflammatory biomarkers during pregnancy are associated with depressive symptomatology in adolescent-aged offspring and to examine how gestational timing, offspring sex, and childhood psychiatric symptoms impact these associations. Design, Setting, and Participants: This was an observational study of a population-based birth cohort from the Child Health and Development Studies (CHDS), which recruited almost all mothers receiving obstetric care from the Kaiser Foundation Health Plan (KFHP) in Alameda County, California, between June 1959 and September 1966. Pregnancy data and blood sera were collected from mothers, and offspring psychiatric symptom data were collected in childhood (ages 9-11 years) and adolescence (ages 15-17 years). Mother-offspring dyads with available maternal prenatal inflammatory biomarkers during first and/or second trimesters and offspring depressive symptom data at adolescent follow-up were included. Data analyses took place between March 2020 and June 2023. Exposures: Levels of inflammatory biomarkers (interleukin 6 [IL-6], IL-8, IL-1 receptor antagonist [IL-1RA], and soluble tumor necrosis factor receptor-II) assayed from maternal sera in the first and second trimesters of pregnancy. Main Outcomes and Measures: Self-reported depressive symptoms at adolescent follow-up. Results: A total of 674 mothers (mean [SD] age, 28.1 [5.9] years) and their offspring (350 male and 325 female) were included in this study. Higher second trimester IL-6 was significantly associated with greater depressive symptoms in offspring during adolescence (b, 0.57; SE, 0.26); P = .03). Moderated mediation analyses showed that childhood externalizing symptoms significantly mediated the association between first trimester IL-6 and adolescent depressive symptoms in male offspring (b, 0.18; 95% CI, 0.02-0.47), while childhood internalizing symptoms mediated the association between second trimester IL-1RA and adolescent depressive symptoms in female offspring (b, 0.80; 95% CI, 0.19-1.75). Conclusions and Relevance: In this study, prenatal maternal inflammation was associated with depressive symptoms in adolescent-aged offspring. The findings of the study suggest that pathways to adolescent depressive symptomatology from prenatal risk factors may differ based on both the timing of exposure to prenatal inflammation and offspring sex.

Individuals with depression exhibiting a pro-inflammatory phenotype receiving omega-3 polyunsaturated fatty acids experience improved motivation-related cognitive function: Preliminary results from a randomized controlled trial.

Cognitive impairment related to major depressive disorder (MDD) is highly prevalent, debilitating and is lacking in effective treatments; dysregulated inflammatory physiology is a putative mechanism and may represent a therapeutic target. In depressed individuals exhibiting a pro-inflammatory phenotype who were enrolled in a 12-week randomized placebo-controlled trial of 3 doses of omega-3 polyunsaturated fatty acids (ω-3-FA), we examined: (i) the relationship between dysregulated inflammatory physiology and baseline cognitive impairment; (ii) improvement in cognitive impairment following treatment; and (iii) the association between baseline inflammatory biomarkers and change in cognitive impairment for those receiving treatment. We randomized 61 unmedicated adults aged 45.50 years (75% female) with DSM-5 MDD, body mass index >25 kg/m2, and C-reactive protein (CRP) ≥3.0 mg/L to three doses of ω-3-FA (1, 2, or 4 g daily) or matching placebo. Analyses focused on 45 study completers who had inflammatory biomarkers assessed [circulating CRP, interleukin-6 (IL-6) and tumor necrosis factor-α (TNFα) as well as lipopolysaccharide (LPS)-stimulated concentrations of IL-6 and TNFα in peripheral blood mononuclear cells (PBMC)] and on the highest dose ω-3-FA (4 g daily; n = 11) compared to placebo (n = 10). Impairment in motivational symptoms (e.g., alertness, energy, enthusiasm) and higher-order cognitive functions (e.g., word-finding, memory) were assessed by a validated self-report measure. Among all 45 participants at baseline, lower concentrations of IL-6 in LPS-stimulated PBMC were associated with greater impairment in higher-order cognitive functions (r = -0.35, p = .02). Based on hierarchical linear modeling, individuals receiving 4 g/day of ω-3-FA reported significant improvement in motivational symptoms compared to placebo (B = -0.07, p = .03); in the 4 g/day group, lower baseline concentrations of TNFα in LPS-stimulated PBMC were associated with significant improvement in motivational symptoms (Ρ = .71, p = .02) following treatment. In this exploratory clinical trial, daily supplementation with 4 g of ω-3-FA improves motivational symptoms in depressed individuals exhibiting an inflammatory phenotype.

Residence in High-Crime Neighborhoods Moderates the Association Between Interleukin 6 and Social and Nonsocial Reward Brain Responses.

BACKGROUND: Residence in high-crime neighborhoods, especially in childhood, is linked to mental health issues later. Detecting distinct neurobiological processes underlying the effects of this environmental stressor may be critical to identifying prevention and intervention targets. This study examined the relationships of levels of a circulating inflammatory protein with social and monetary reward-related brain function among adolescents who lived in high- versus low-crime neighborhoods during childhood. METHODS: A total of 70 participants (mean age = 16.3 years; 57% female) completed measures of inflammatory markers, depression history, and health and 2 functional magnetic resonance imaging tasks assessing responsivity to monetary and social rewards. Multivariate linear regression tested whether individuals with higher interleukin 6, an inflammatory cytokine, who also lived in neighborhoods with higher crime had distinct orbitofrontal cortex and nucleus accumbens activation to monetary reward and social acceptance. RESULTS: For adolescents who lived in neighborhoods with more crime, higher interleukin 6 was associated with higher nucleus accumbens responses to social acceptance. We did not detect significant moderating effects of neighborhood crime rates on the associations of interleukin 6 with orbitofrontal cortex responses to social acceptance or orbitofrontal cortex/nucleus accumbens activation during monetary reward anticipation or outcome. These results were obtained before and after adjusting for neighborhood income and other covariates. We did not detect significant moderating effects of neighborhood income. CONCLUSIONS: High-threat residence environment and specific demands of the social context in childhood may have shaped the effect of peripheral immune activation on reward-related neural function in adolescence. The prevailing view that inflammation-associated behaviors are characterized by blunted responsiveness to reward may be oversimplistic.