Population Neuroscience: Understanding Concepts of Generalizability and Transportability and Their Application to Improving the Public's Health

In population neuroscience, samples are not often selected with equal or known probability from an underlying population of interest; in other words, samples are not often formally representative of a specified underlying population. This chapter provides an overview of an epidemiological approach to considering the implications of selective participation on the value of our results for population health. We discuss definitions of generalizability and transportability, given the growing recognition that generalizability and transportability are central for interpreting data that are aiming to be population-based. We provide evidence that differences in the prevalence of effect measure modifiers between a study sample and a target population will lead to a lack of generalizability and transportability. We provide an example of an association between a poly-genetic risk score and depression, showing how an internally valid association can differ based on the prevalence of effect measure modifiers. We show that when estimating associations, inferences from a study sample to a population can depend on clearly defining a target population. Given that representative sampling from explicitly defined target populations may not be feasible or realistic in many situations, especially given the sample sizes needed for statistical power for many exposures of interest (and especially when interactions are being tested), researchers should be well versed in tools available to enhance the interpretability of samples regarding target populations.

Country-level gender inequality is associated with structural differences in the brains of women and men

Gender inequality across the world has been associated with a higher risk to mental health problems and lower academic achievement in women compared to men. We also know that the brain is shaped by nurturing and adverse socio-environmental experiences. Therefore, unequal exposure to harsher conditions for women compared to men in gender-unequal countries might be reflected in differences in their brain structure, and this could be the neural mechanism partly explaining women's worse outcomes in gender-unequal countries. We examined this through a random-effects meta-analysis on cortical thickness and surface area differences between adult healthy men and women, including a meta-regression in which country-level gender inequality acted as an explanatory variable for the observed differences. A total of 139 samples from 29 different countries, totaling 7,876 MRI scans, were included. Thickness of the right hemisphere, and particularly the right caudal anterior cingulate, right medial orbitofrontal, and left lateral occipital cortex, presented no differences or even thicker regional cortices in women compared to men in gender-equal countries, reversing to thinner cortices in countries with greater gender inequality. These results point to the potentially hazardous effect of gender inequality on women's brains and provide initial evidence for neuroscience-informed policies for gender equality.

Placebo response in trials with patients with anxiety, obsessive-compulsive and stress disorders across the lifespan: a three-level meta-analysis

QUESTION

Randomised controlled trials assessing treatments for anxiety, obsessive-compulsive and stress-related disorders often present high placebo response rates in placebo groups. Understanding the placebo response is essential in accurately estimating the benefits of pharmacological agents; nevertheless, no studies have evaluated the placebo response across these disorders using a lifespan approach.

STUDY SELECTION AND ANALYSIS

We searched MEDLINE, PsycINFO, Embase, Cochrane, websites of regulatory agencies and international registers from inception to 9 September 2022. The primary outcome was the aggregate measure of internalising symptoms of participants in the placebo arms of randomised controlled trials designed to assess the efficacy of selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) in individuals diagnosed with anxiety, obsessive-compulsive or stress-related disorders. The secondary outcomes were placebo response and remission rates. Data were analysed through a three-level meta-analysis.

FINDINGS

We analysed 366 outcome measures from 135 studies (n=12 583). We found a large overall placebo response (standardised mean difference (SMD)=-1.11, 95% CI -1.22 to -1.00). The average response and remission rates in placebo groups were 37% and 24%, respectively. Larger placebo response was associated with a diagnosis of generalised anxiety disorder and post-traumatic stress disorder, when compared with panic, social anxiety and obsessive-compulsive disorder (SMD range, 0.40-0.49), and with absence of a placebo lead-in period (SMD=0.44, 95% CI 0.10 to 0.78). No significant differences were found in placebo response across age groups. We found substantial heterogeneity and moderate risk of bias.

CONCLUSIONS

Placebo response is substantial in SSRI and SNRI trials for anxiety, obsessive-compulsive and stress-related disorders. Clinicians and researchers should accurately interpret the benefits of pharmacological agents in contrast to placebo response.

PROSPERO REGISTRATION NUMBER

CRD42017069090.

Implementation of Group Interpersonal Psychotherapy in primary care

OBJECTIVE

To show the implementation process of IPT-G in primary care, including facilitating and obstructing factors, implementation strategies, and training and supervision of primary care professionals.

METHODS

Quantitative (cross-sectional and longitudinal) analysis of pre and post-knowledge tests; qualitative analyses of the training courses; patient recruitment; conduction of IPT-G sessions; supervision of IPT-G therapists; application of a semi-structured questionnaire to assess, investigate, and develop strategies against the identified barriers.

RESULTS

About 120 clinicians answered the pre-test; 84 completed the post-test. Pre- and post-test scores of IPT-G knowledge were significantly different. Twenty initially trained clinicians completed additional supervision in IPT-G. Qualitative analysis identified twelve barriers and six facilitators to IPT-G implementation in individual, organizational, and systemic contexts.

CONCLUSIONS

Implementation of IPT-G in primary care is a complex process with several steps. In the first step, health professionals were successfully trained in IPT-G. However, subsequent steps were more complex. Therefore, careful planning of IPT-G implementation is essential to maximize the success of this innovation.

Cellular correlates of cortical thinning throughout the lifespan

Cortical thinning occurs throughout the entire life and extends to late-life neurodegeneration, yet the neurobiological substrates are poorly understood. Here, we used a virtual-histology technique and gene expression data from the Allen Human Brain Atlas to compare the regional profiles of longitudinal cortical thinning through life (4004 magnetic resonance images [MRIs]) with those of gene expression for several neuronal and non-neuronal cell types. The results were replicated in three independent datasets. We found that inter-regional profiles of cortical thinning related to expression profiles for marker genes of CA1 pyramidal cells, astrocytes and, microglia during development and in aging. During the two stages of life, the relationships went in opposite directions: greater gene expression related to less thinning in development and vice versa in aging. The association between cortical thinning and cell-specific gene expression was also present in mild cognitive impairment and Alzheimer's Disease. These findings suggest a role of astrocytes and microglia in promoting and supporting neuronal growth and dendritic structures through life that affects cortical thickness during development, aging, and neurodegeneration. Overall, the findings contribute to our understanding of the neurobiology underlying variations in MRI-derived estimates of cortical thinning through life and late-life disease.

Corticosteroids and Regional Variations in Thickness of the Human Cerebral Cortex across the Lifespan

Exposures to life stressors accumulate across the lifespan, with possible impact on brain health. Little is known, however, about the mechanisms mediating age-related changes in brain structure. We use a lifespan sample of participants (n = 21 251; 4-97 years) to investigate the relationship between the thickness of cerebral cortex and the expression of the glucocorticoid- and the mineralocorticoid-receptor genes (NR3C1 and NR3C2, respectively), obtained from the Allen Human Brain Atlas. In all participants, cortical thickness correlated negatively with the expression of both NR3C1 and NR3C2 across 34 cortical regions. The magnitude of this correlation varied across the lifespan. From childhood through early adulthood, the profile similarity (between NR3C1/NR3C2 expression and thickness) increased with age. Conversely, both profile similarities decreased with age in late life. These variations do not reflect age-related changes in NR3C1 and NR3C2 expression, as observed in 5 databases of gene expression in the human cerebral cortex (502 donors). Based on the co-expression of NR3C1 (and NR3C2) with genes specific to neural cell types, we determine the potential involvement of microglia, astrocytes, and CA1 pyramidal cells in mediating the relationship between corticosteroid exposure and cortical thickness. Therefore, corticosteroids may influence brain structure to a variable degree throughout life.

Debate: Dimensions of mania in youth: possibly bipolar, probably risk indicators, certainly impairing

We comment on the utility of latent manic dimensions to elucidate the prevalence of youth Bipolar Disorder in epidemiological samples, irrespective of sample's cultural background or clinician's predetermined prototypical definitions of a bipolar case.

Adaptação transcultural do Inventory of Callous-Unemotional Traits para avaliação de traços de insensibilidade e afetividade restrita de adolescentes no Brasil

RESUMO Objetivo Realizar a adaptação transcultural para o português brasileiro do instrumento Inventory of Callous-Unemotional Traits (ICU) para avaliação de traços de insensibilidade e afetividade restrita de adolescentes. Método Estudo metodológico que envolveu as etapas de tradução, retradução, avaliação por comitê de especialistas e de clareza da versão pré-final do ICU, avaliado por 40 adolescentes, entre 10 e 17 anos, de ambos os sexos, de uma escola pública. Resultados A versão pré-final do ICU foi aprovada pelo comitê de especialistas e pelo autor do instrumento. A avaliação da clareza revelou uma boa compreensão dos itens. Os 10 itens com menor clareza foram modificados conforme as sugestões. Conclusão A versão final do ICU para o português brasileiro mostrou ser similar ao instrumento original no que se refere à equivalência semântica, operacional e conceitual. Recomenda-se a realização de estudos que evidenciem a validade psicométrica do ICU adaptado para o português brasileiro.

Testing Measurement Invariance across Groups of Children with and without Attention-Deficit/ Hyperactivity Disorder: Applications for Word Recognition and Spelling Tasks

Although studies have consistently demonstrated that children with attention-deficit/hyperactivity disorder (ADHD) perform significantly lower than controls on word recognition and spelling tests, such studies rely on the assumption that those groups are comparable in these measures. This study investigates comparability of word recognition and spelling tests based on diagnostic status for ADHD through measurement invariance methods. The participants (n = 1,935; 47% female; 11% ADHD) were children aged 6–15 with normal IQ (≥70). Measurement invariance was investigated through Confirmatory Factor Analysis and Multiple Indicators Multiple Causes models. Measurement invariance was attested in both methods, demonstrating the direct comparability of the groups. Children with ADHD were 0.51 SD lower in word recognition and 0.33 SD lower in spelling tests than controls. Results suggest that differences in performance on word recognition and spelling tests are related to true mean differences based on ADHD diagnostic status. Implications for clinical practice and research are discussed.

Gene expression in blood of children and adolescents: Mediation between childhood maltreatment and major depressive disorder

Investigating major depressive disorder (MDD) in childhood and adolescence can help reveal the relative contributions of genetic and environmental factors to MDD, since early stages of disease have less influence of illness exposure. Thus, we investigated the mRNA expression of 12 genes related to the hypothalamic-pituitary-adrenal (HPA) axis, inflammation, neurodevelopment and neurotransmission in the blood of children and adolescents with MDD and tested whether a history of childhood maltreatment (CM) affects MDD through gene expression. Whole-blood mRNA levels of 12 genes were compared among 20 children and adolescents with MDD diagnosis (MDD group), 49 participants without MDD diagnosis but with high levels of depressive symptoms (DS group), and 61 healthy controls (HC group). The differentially expressed genes were inserted in a mediation model in which CM, MDD, and gene expression were, respectively, the independent variable, outcome, and intermediary variable. NR3C1, TNF, TNFR1 and IL1B were expressed at significantly lower levels in the MDD group than in the other groups. CM history did not exert a significant direct effect on MDD. However, an indirect effect of the aggregate expression of the 4 genes mediated the relationship between CM and MDD. In the largest study investigating gene expression in children with MDD, we demonstrated that NR3C1, TNF, TNFR1 and IL1B expression levels are related to MDD and conjunctly mediate the effect of CM history on the risk of developing MDD. This supports a role of glucocorticoids and inflammation as potential effectors of environmental stress in MDD.

Inflammatory markers in post-traumatic stress disorder: a systematic review, meta-analysis, and meta-regression

BACKGROUND

Studies investigating inflammatory markers in post-traumatic stress disorder (PTSD) have yielded mixed results. The aim of our study was to compare concentrations of inflammatory markers in patients with PTSD compared with healthy controls.

METHODS

We did a meta-analysis and meta-regression of studies comparing inflammatory markers between patients with PTSD and healthy controls by searching PubMed, Embase, Scopus, Web of Science, and PsycINFO for articles published between Jan 1, 1960, and April 7, 2015. From eligible studies (ie, cross-sectional studies or baseline data from longitudinal studies of peripheral blood cytokine concentrations that compared adults with PTSD with healthy controls), we extracted outcomes of interest, such as mean and SD of peripheral blood cytokines, the time of day blood was collected, whether the study allowed patients with comorbid major depressive disorder in the PTSD group, whether patients were medication free, and severity of PTSD symptoms. We undertook meta-analyses whenever values of inflammatory markers were available in two or more studies. A random-effects model with restricted maximum-likelihood estimator was used to synthesise the effect size (assessed by standardised mean difference [SMD]) across studies.

FINDINGS

8057 abstracts were identified and 20 studies were included. Interleukin 6 (SMD 0.88; p=0.0003), interleukin 1β (SMD 1.42; p=0.045), and interferon γ (SMD 0.49; p=0.002) levels were higher in the PTSD group than in healthy controls. Subgroup meta-analysis of patients who were not given medication showed higher tumour necrosis factor α (TNFα; SMD 0.69, 95% CI 0.35-1.02; p<0.0001) in the PTSD group than the control group in addition to the aforementioned cytokines. TNFα (SMD 1.32, 0.13-2.50; p=0.003), interleukin 1β (SMD 2.35, 0.01-4.68; p=0.048), and interleukin 6 (SMD 1.75, 0.97-2.53; p<0.0001) levels remained increased in the PTSD group in a subgroup meta-analysis of studies that excluded comorbid major depressive disorder. Illness duration was positively associated with interleukin 1β levels (b=0.33, p<0.0001) and severity with interleukin 6 (b=0.02, p=0.042). A model composed of several variables-presence of comorbid major depressive disorder, use of psychotropic medications, assay used, and time of day blood was collected-explained the large amount of heterogeneity between interleukin 1β, interleukin 6, and C-reactive protein studies. Egger's linear regression test revealed a potential publication bias for interleukin 1β. Additionally, for most inflammatory markers, study heterogeneity was reported to be high (I(2)>75%).

INTERPRETATION

PTSD is associated with increased interleukin 6, interleukin 1β, TNFα, and interferon γ levels. This information might be useful for consideration of chronic low-grade inflammation as a potential target or biomarker in PTSD treatment. Use of psychotropic medication and presence of comorbid major depressive disorder were important moderators that might explain the inconsistency between results of previous studies. Our search strategy used a range of databases and we made exhaustive effort to acquire data by contacting the authors. Notably, high levels of between-study heterogeneity were recorded for most cytokine variables measured in our analysis. However, meta-regression analysis could explain a large amount of this heterogeneity.

FUNDING

None.

Dimensions of oppositionality in a Brazilian community sample: testing the DSM-5 proposal and etiological links

OBJECTIVE

Investigating dimensions of oppositional symptoms may help to explain heterogeneity of etiology and outcomes for mental disorders across development and provide further empirical justification for the DSM-5-proposed modifications of oppositional defiant disorder (ODD). However, dimensions of oppositionality have not previously been tested in samples outside Europe or the United States. In this study, we used a large Brazilian community sample to compare the fit of different models for dimensions of oppositional symptoms; to examine the association of psychiatric diagnoses and symptoms with dimensions of oppositionality; and to examine the associations between dimensions of oppositionality and parental history of mental disorders.

METHOD

A Brazilian community sample of 2,512 children 6 through 12 years old were investigated in this study. Confirmatory factorial analyses were performed to compare the fit of alternative models, followed by linear and logistic regression analyses of associations with psychiatric diagnosis and parental history of psychopathology.

RESULTS

A three-factor model with irritable, headstrong, and hurtful dimensions fitted best. The irritable dimension showed a strong association with emotional disorders in the child (p<.001) and history of depression (p<.01) and suicidality (p<.05) in the mother. The headstrong dimension was uniquely associated with attention-deficit/hyperactivity disorder (ADHD) in the child (p<.001) and with maternal history of ADHD symptoms (p<.05). The hurtful dimension was specifically associated with conduct disorder (p< .05).

CONCLUSIONS

Our findings from a large community sample of Brazilian children support a distinction between dimensions of oppositionality consistent with current DSM-5 recommendations and provide further evidence for etiological distinctions between these dimensions.

Reliability and convergent validity of the Childhood Anxiety Sensitivity Index in children and adolescents

OBJECTIVE: The purpose of this study was to examine the reliability and the convergent validity of the Children Anxiety Sensitivity Index (CASI) with DSM-IV anxiety disorder symptoms, by comparison with the Screen for Child Anxiety Related Emotional Disorders (SCARED), in a community sample of Brazilian children and adolescents. METHODS: Children and adolescents from five schools were selected from a larger study that aimed to assess different aspects of childhood anxiety disorders. All participants completed the CASI and the SCARED. RESULTS: This study supported the reliability of the CASI total score. Girls reported higher total anxiety sensitivity scores than boys and there were no differences in total anxiety sensitivity scores between children and adolescents. This study showed moderate to high correlations between the CASI scores with SCARED scores, all correlations coefficients being positive and significant. CONCLUSIONS: Our findings demonstrate an appropriate reliability and evidence of convergent validity in the CASI in a sample of Brazilian children and adolescents.

Mutant p53 protein in serum could be used as a molecular marker in human breast cancer

p53 wild-type is a tumor suppressor gene involved in DNA gene transcription or DNA repair mechanisms. When damage to DNA is unrepairable, p53 induces programmed cell death (apoptosis). The mutant p53 gene is the most frequent molecular alteration in human cancer, including breast cancer. Here, we analyzed the genetic alterations in p53 oncogene expression in 55 patients with breast cancer at different stages and in 8 normal women. We measured by ELISA assay the serum levels of p53 mutant protein and p53 antibodies. Immunohistochemistry and RT-PCR using specific p53 primers as well as mutation detection by DNA sequencing were also evaluated in breast tumor tissue. Serological p53 antibody analysis detected 0/8 (0%), 0/4 (0%) and 9/55 (16.36%) positive cases in normal women, in patients with benign breast disease and in breast carcinoma, respectively. We found positive p53 mutant in the sera of 0/8 (0.0%) normal women, 0/4 (0%) with benign breast disease and 29/55 (52.72%) with breast carcinoma. Immunohistochemistry evaluation was positive in 29/55 (52.73%) with mammary carcinoma and 0/4 (0%) with benign breast disease. A very good correlation between p53 mutant protein detected in serum and p53 accumulation by immunohistochemistry (83.3% positive in both assays) was found in this study. These data suggest that detection of mutated p53 could be a useful serological marker for diagnostic purposes.

Double modulation of 5-fluorouracil by trimetrexate and leucovorin in patients with advanced colorectal carcinoma

The purpose of this report is to evaluate the efficacy and toxicity (Tx) of a double modulation of 5-fluorouracil (5-FU) by trimetrexate (TMTX) and leucovorin (LV) in patients with advanced recurrent (inoperable) or metastatic colorectal cancer (ACC). Between December 1997 and August 2000, 36 patients were entered in this phase II study. Median age was 61 years, and 18 patients (50%) were female. Median performance status was 0 (range: 0-1), whereas primary tumor location was colon in 21 patients (58%) and rectum in 15 patients (42%). The number of metastatic sites was 1:29 patients (81%); 2:6 patients (17%) and 3:1 patient (3%). Hepatic involvement was observed in 33 patients (92%). Treatment consisted of TMTX 110 mg/m2 IV over 1 hour at hour (H) 0; LV 50 mg/m2 IV over 2 hours IV infusion starting at H 18; and 5-FU 900 mg/m2 IV bolus at H 20. LV (rescue) 15 mg/m2 orally was administered every 6 hours (total 6 doses) beginning at H 24. Cycles were repeated every 2 weeks until progressive disease (PD) or severe Tx. Thirty-four patients are assessable for response (R) (two patients refused further treatment after the first course of therapy), whereas all patients were assessable for Tx. Complete response: 1 patient (3%); partial response: 4 patients (12%), with an overall objective response rate of 15% (95% CI, 1%-25%); no change: 12 patients (35%); and progressive disease: 17 patients (50%). The median time to treatment failure was 4 months and median survival was 11 months. Tx was within acceptable limits. The dose-limiting side effect was mucositis. Eight episodes of grade II or III stomatitis were observed and were responsible for dosage modifications of TMTX and 5-FU. Leukopenia was observed in 16 patients (44%); neutropenia was registered in 19 patients (53%); anemia was seen in 18 patients (50%); emesis in 22 patients (61%); and dermatitis in 3 patients (8%). There were no therapy-related deaths. The double modulation of 5-FU by TMTX and LV showed modest antitumoral activity with mild to moderate Tx.

Low-dose continuous oral fosfestrol is highly active in 'hormone-refractory' prostate cancer

BACKGROUND

Although not clearly defined, 'hormone refractory' prostate cancer implies disease progression after orchiectomy +/- antiandrogens. Patients in this setting are usually offered chemotherapy protocols which often lead to significant toxicity and expense. In search of a well-tolerated, active, third-line treatment, we have attempted to prolong hormonal maneuvers by using low-dose estrogen therapy.

DESIGN

Thirty-eight patients with evidence of disease progression (as indicated by 2 consecutively rising PSA determinations) after > or = 2 hormonal treatments (including surgical or chemical orchiectomy and a median of 3 prior treatment lines) received fosfestrol 100 mg t.i.d. per os in a continuous schedule until the appearance of progressive disease or excessive toxicity. Response was assessed by serial PSA levels. Complete response (CR) was defined as normalisation and partial response (PR) as a > or = 50 decrease of PSA levels for longer than one month. The median duration of prior treatment was 20 months and the median PSA at fosfestrol start was 126 ng/ml (range 8-12,800); symptoms (pain) were present in 73% of patients.

RESULTS

CR + PR were observed in 79% (95% confidence interval: 66%-92%). The median time to progression was seven months. Pain remained stable or improved in 34% and 53%, respectively, of symptomatic patients with PSA response. Toxicity included worsening of gynecomastia, peripheral edema, and deep vein thrombosis (8%). No treatment-related deaths occurred. Uni- and multivariate analyses failed to identify predictive factors for response. PSA response was associated with significantly longer survival (13 vs. 7 months, P < 0.05 by Mantel-Haentzel).

CONCLUSIONS

FOSF produces high rates of PSA-determined and symptomatic response in 'hormone-refractory' prostate cancer. Toxicity and ease of administration compare favorably with those reported for CHT regimens used in this setting. The role of estrogens in prostate cancer should be redefined.