The study was conducted by Aline Debener and Ann-Katrin Job using data from the German Future Family project, a prospective longitudinal study that began in 2001 with 280 families recruited from randomly selected kindergartens in Braunschweig and later expanded with 197 additional families from socially disadvantaged urban areas. The project originally tested the effectiveness of the Triple P preventive parenting program and has tracked child and family development for more than 18 years. The analyses reported in the new paper drew on the 10-year follow-up in adolescence and the 18-year follow-up in emerging adulthood, both funded by the German Research Foundation. After excluding father-child dyads and families with missing participation, the final sample comprised 224 mother-child pairs, 52 percent of them daughters, with 98 percent of the reporters being biological mothers.

To measure psychopathology, the researchers used parallel questionnaires that capture the same symptoms from two vantage points. In adolescence, children completed the Youth Self Report while mothers completed the Child Behavior Checklist; in emerging adulthood, the pair became the Adult Self Report and the Adult Behavior Checklist. Each version yields scores for internalizing problems, such as anxiety and depression, and externalizing problems, such as aggression and rule-breaking, covering the previous six months. Internal consistency of the scales was high at both waves. The team also measured current psychological distress in children with the Strengths and Difficulties Questionnaire and in mothers with the Depression Anxiety Stress Scales, assessed the mother-child relationship through the Family Climate Scales, and derived family socioeconomic status from education, occupation, and income.

Agreement was operationalized as the correlation between the raw scores of the paired questionnaires. In adolescence, the correlations were moderate: r = .35 for internalizing problems and r = .40 for externalizing problems. By emerging adulthood, agreement had risen to r = .53 for internalizing and r = .50 for externalizing problems. A Steiger test confirmed that the increase for internalizing problems was statistically significant, while the change for externalizing problems was not, possibly due to limited statistical power or the greater observability of externalizing behavior, which may leave less room for consistency to vary. Notably, there were no significant differences at either time point between the levels of agreement for internalizing and externalizing problems, addressing a long-standing question about whether hidden emotional problems are harder to agree on than visible behavioral ones.

The categorical analysis of discrepancies told a complementary story. Using standardized difference scores, the researchers classified each dyad as showing agreement, a positive discrepancy in which the child reported more problems than the mother, or a negative discrepancy in which the mother reported more. Roughly two-thirds to three-quarters of dyads showed no relevant discrepancy at each wave, and discrepancies became less common over time. More than half of the dyads showed no discrepancy at either wave for either problem domain, and a shift from discrepancy to agreement occurred far more often than the reverse. Only a small minority of families maintained a stable positive or negative discrepancy across the eight-year span, and almost none flipped from one direction to the other.

The predictors of discrepancy differed sharply depending on its direction, a finding the authors emphasize as clinically important. When adolescents reported more problems than their mothers, the strongest predictor was the child’s current psychological distress: more distressed adolescents produced larger positive discrepancies, accounting for over half of the explainable variance for internalizing problems and about 70 percent for externalizing problems. Maternal distress played a smaller role. When mothers reported more problems than their children, the child’s male sex was the only significant predictor in adolescence, suggesting that mothers of sons may perceive more symptoms than their sons are willing to report, possibly because male adolescents downplay their difficulties while young women tend to show more openness about mental health.

Predicting discrepancies in emerging adulthood from adolescent variables proved possible only for negative discrepancies, where mothers reported higher symptom levels than their children. The adolescent discrepancy itself was the dominant predictor, explaining roughly 60 percent of the explainable variance, which points to a stable tendency among some mothers to overestimate their children’s problems. For externalizing problems, higher child distress in adolescence also predicted a larger negative discrepancy in adulthood, consistent with the idea that worried mothers may selectively attend to signs of trouble. For positive discrepancies in externalizing problems, the family climate mattered: less mutual affection combined with more shared leisure activities predicted larger discrepancies, with affection carrying the greatest relative weight. The authors suggest that mothers who perceive problems in their children may intervene more, generating conflict, or that children who share less affectionate relationships disclose fewer symptoms.

The study has limitations that temper interpretation. Fathers were excluded because too few participated, the sample contained few low socioeconomic status families, dropout analyses showed that families lost to follow-up had more mental health problems and greater vulnerability, and the second wave of data collection occurred largely during the COVID-19 pandemic, which elevated mental health problems in young adults. The adult questionnaires also lack German standardization, so raw and standardized scores were used without clinical cutoffs, and the item composition of the adolescent and adult questionnaires differs slightly. A post-hoc power analysis revealed statistical power ranging from insufficient to very high across models, which the authors link to the split samples required for analyzing positive and negative discrepancies separately.

Despite these caveats, the implications are substantial. The findings confirm that self-reports and maternal reports are not interchangeable at any age, yet each contributes unique information, and their convergence strengthens as children mature, possibly because young adults become better at articulating internal states and because their views gradually align with their mothers’ long-standing assessments. The authors recommend that clinicians routinely seek collateral reports beyond childhood and adolescence to sharpen diagnosis and individualize treatment, and that researchers weigh the direction of any discrepancy, the child’s current distress, the quality of the mother-child relationship, and the child’s sex when interpreting multi-informant data. They also call for studies including fathers, partners, and other informants, symptom-specific analyses, cross-cultural comparisons, and work extending beyond emerging adulthood, where the trajectory of informant agreement remains largely unexplored.

For a field that has long treated discrepant reports as statistical noise to be averaged away, this study adds to a growing consensus that disagreements between informants are signals worth reading. A mother who sees more distress in her son than he admits, or a distressed daughter who reports symptoms her mother misses, is not simply producing error; she is offering a perspective shaped by attachment, observation, and the developmental moment. As longitudinal cohorts age and multi-informant assessment becomes standard in both research and care, knowing when and why mothers and children converge, and when their divergent views carry clinical meaning, may prove as important as any single report itself.

Subject of Research: Longitudinal agreement and discrepancies between self-reported and mother-reported psychopathology from adolescence to emerging adulthood

Article Title: Agreement and Discrepancies of Self- and Mother Reported Psychopathology from Adolescence Until Emerging Adulthood: Results of a Prospective Longitudinal Study

Article References: Debener, A., & Job, A.-K. (2026). Agreement and Discrepancies of Self- and Mother Reported Psychopathology from Adolescence Until Emerging Adulthood: Results of a Prospective Longitudinal Study. Child Psychiatry & Human Development. https://doi.org/10.1007/s10578-026-02095-3

Image Credits: AI Generated

DOI: 10.1007/s10578-026-02095-3

Keywords: informant discrepancies, cross-informant agreement, psychopathology, adolescence, emerging adulthood, longitudinal study, mother-child relationship, internalizing problems, externalizing problems, psychological distress, Child Behavior Checklist, mental health assessment

The findings arrive amid a widening scientific debate over fluoride, a substance added to community water supplies at 0.7 milligrams per litre to prevent tooth decay, yet one that occurs naturally in groundwater at levels that can vary dramatically with local geology. In rural New Hampshire, where many families rely on private, unregulated wells drilled into fluoride-bearing rock, concentrations can be far higher than in fluoridated municipal systems; roughly thirteen percent of wells in regions underlain by felsic igneous rock exceed the U.S. Environmental Protection Agency’s secondary maximum contaminant level of 2.0 milligrams per litre. Against this backdrop, the research team set out to test whether prenatal fluoride exposure is linked not to intelligence, which has dominated the literature, but to the social-emotional and behavioural dimensions of child development that have received far less scrutiny.

Methodologically, the study distinguishes itself through its choice of exposure biomarker. Most previous prospective studies relied on maternal urinary fluoride, which reflects intake over only about six hours—a snapshot that can fluctuate with tea drinking, meal composition, and water consumption on a given day. Toenails, by contrast, grow slowly and integrate fluoride exposure over approximately three to six months, capturing cumulative intake from all sources: drinking water, beverages prepared with fluoridated water, seafood, tea, and the inadvertent swallowing of fluoridated dental products. Because fluoride readily crosses the placenta and penetrates the blood-brain barrier, the developing fetal brain is directly exposed, making the timing and magnitude of maternal exposure biologically consequential.

The researchers analyzed toenail clippings collected from women at roughly 28 weeks of gestation and again about five weeks after delivery, yielding estimates of fluoride exposure during early pregnancy and mid-to-late pregnancy respectively. Samples were analyzed at the Indiana University School of Dentistry using a hexamethyldisiloxane microdiffusion procedure coupled with fluoride ion-selective electrode detection, and specimens weighing less than 2.5 milligrams were excluded after validation work showed that smaller samples produce unreliable results. Household tap water collected at enrollment was analyzed with a fluoride ion-selective electrode as well. The final analytic samples comprised 358 mother-child pairs with toenail fluoride data and 381 pairs with water fluoride data, drawn from a cohort recruited between 2009 and 2013 from prenatal clinics serving women using private water systems.

Children’s behaviour was assessed at age five with the Behavior Assessment System for Children, Second Edition, Parent Rating Scale for preschoolers, a validated instrument that generates age-standardized T-scores across clinical scales such as hyperactivity, aggression, attention problems, anxiety, depression, and withdrawal, along with composite indices of externalizing problems, internalizing problems, and overall behavioural symptoms. Scores of 60 or above fall into the at-risk range. In this sample, most children scored near the normative mean, with between six and twenty-eight percent in the at-risk range depending on the scale. The analysis was preregistered, and the modeling strategy used generalized estimating equations to estimate the odds of at-risk outcomes per one microgram per gram increase in toenail fluoride, with interaction terms testing for differences by child sex and exposure window.

The headline result was statistically robust: each one microgram per gram increase in toenail fluoride reflecting early pregnancy was associated with thirty-nine percent higher odds of scoring in the at-risk range for externalizing problems, with a confidence interval running from fifteen to sixty-seven percent above baseline. The late-pregnancy estimate was similar in magnitude, at thirty percent higher odds, though its confidence interval narrowly included the null. On the individual clinical scales, early-pregnancy fluoride was linked to twenty percent higher odds of at-risk hyperactivity, and the late-pregnancy estimate of twenty-four percent approached significance. The pattern suggests that no single trimester stands out as uniquely vulnerable; rather, fluoride exposure across pregnancy appears relevant to externalizing behaviour.

The sex-specific findings added a further layer of complexity. Among girls, each one microgram per gram increase in early-pregnancy toenail fluoride was associated with thirty-seven percent higher odds of at-risk depressive symptoms, while no association appeared in boys—a statistically significant interaction. Suggestive but imprecise signals also emerged for anxiety and withdrawal in girls in relation to late-pregnancy exposure. This pattern is intriguing because prior fluoride studies, particularly those examining intelligence outcomes, have often reported stronger effects in boys. The authors note that internalizing and externalizing problems may share transdiagnostic roots, including emotion dysregulation, and that sex-specific biological responses to prenatal exposures could shape which behavioural domain is affected.

Plausible biological mechanisms are beginning to take shape in the literature. Fluoride has been implicated in disruption of the thyroid axis, a concern in pregnancy because the fetus depends entirely on maternal thyroid hormones during the first trimester, and even mild maternal thyroid dysfunction has been linked to both internalizing and externalizing problems in children. Fluoride exposure has also been shown to induce oxidative stress in animal and human studies, a pathway independently associated with behavioural problems in offspring. Low iodine status, which compromises thyroid hormone synthesis, may exacerbate fluoride’s effects, and emerging evidence suggests thyroid regulation and oxidative stress responses differ by fetal sex. None of these mechanisms is confirmed as the driver of the observed associations, but together they offer a coherent framework for future investigation.

Why did water fluoride fail to predict outcomes while toenail fluoride succeeded? The authors argue that toenails capture total intake from all dietary and product sources, whereas a single tap-water measurement reflects only one exposure pathway and ignores individual differences in consumption volume. This mismatch can produce exposure misclassification that biases associations toward the null. Median water fluoride in the sample was about 0.2 milligrams per litre—comparable to other communities with naturally occurring fluoride—but values ranged from 0.02 to 13.8 milligrams per litre, and correlations between water and toenail measures, while positive, were moderate. The authors also caution that some participants may have reduced tap-water consumption after learning their wells exceeded arsenic guidelines during the study.

The study’s limitations temper its implications. The cohort was predominantly white, college-educated, married, and relatively affluent, and relied on unregulated private wells, so the findings cannot be assumed to extend to populations drinking optimally fluoridated municipal water. Postnatal fluoride exposure was not measured, toenail growth rates vary between individuals, and only a small fraction of children scored in the at-risk range, limiting statistical power. Yet extensive sensitivity analyses—adjusting for co-occurring metals, imputing missing data, removing influential observations, and modeling outcomes continuously—left the primary conclusions intact. The authors call for longitudinal follow-up, validation of toenail fluoride reference ranges in pregnant populations, and exposome-wide approaches that jointly model fluoride alongside the many other prenatal environmental exposures that shape the developing brain.

Subject of Research: The association between prenatal fluoride exposure measured in maternal toenails and social-emotional and behavioural outcomes in preschool children.

Article Title: Long-term exposure to prenatal fluoride and social-emotional and behavioural outcomes in children in the New Hampshire Birth Cohort Study

Article References: Goodman, C. V., Karagas, M. R., Peacock, J. L., Korrick, S., Flora, D., Lanphear, B., Martinez-Mier, E. A., Tamayo-Cabeza, G., Lippert, F., & Till, C. (2026). Long-term exposure to prenatal fluoride and social-emotional and behavioural outcomes in children in the New Hampshire Birth Cohort Study. Environmental Advances, 25, Article 100753. https://doi.org/10.1016/j.envadv.2026.100753

Image Credits: AI Generated

DOI: 10.1016/j.envadv.2026.100753

Keywords: fluoride, prenatal exposure, child behaviour, hyperactivity, New Hampshire Birth Cohort Study, toenail biomarker, drinking water, neurodevelopment, thyroid, externalizing problems, internalizing problems, private wells