Sex differences in predicting ADHD clinical diagnosis and pharmacological treatment

Child and Parental Characteristics of Medication Use for Attention-Deficit/Hyperactivity Disorder

Objectives: To investigate child and parental characteristics of medication use for attention-deficit/hyperactivity disorder (ADHD). Methods: Participants were part of the prospective population-based Norwegian Mother, Father and Child Cohort study (MoBa) (n = 114,500 children, 95,000 mothers, and 75,000 fathers). This cohort was linked to the Norwegian Prescription Database (NorPD) and the Norwegian Patient Registry (NPR) to compare child and parental characteristics in children medicated and not medicated for ADHD during years 2008-2013. Results: One thousand seven hundred and sixty-four children (74% boys) with ADHD (International Classification of Diseases [ICD-10]: F90 and F98.8) were identified. One thousand three hundred and sixty-two (77%) used medication. Boys and girls did not differ in the use of ADHD medication (both 77%). Mean age at first prescription was 9 years in both boys and girls, and age at ADHD diagnosis was 8 years in medicated and unmedicated children. Significantly more hyperkinetic conduct disorders (F90.1), and significantly fewer with attention-deficit disorder (F98.8) were found among the medicated children compared to the unmedicated children. The medicated children also had a significantly lower global functioning (Child Global Assessment Scale). Child disruptive symptoms reported in the MoBa child age 3 year questionnaire were significantly higher in children who used medication compared to the nonusers (t = 2.2, p = 0.03), and group differences in ADHD symptoms at age 3 years were close to significant (t = 1.8, p = 0.07). Other preschool child and parental characteristics were not significantly different in the two groups. Conclusion: In this large birth cohort study, where a great majority of children with ADHD used medication, only child characteristics were significantly associated with the use of medication. We could not replicate previous findings suggesting that "environmental factors," such as parental education and psychopathology, drive medication use. The small differences between medicated and unmedicated children in this cohort study, where a majority used medication, might be due to strong established clinical practices where medication is offered as a treatment option, particularly for hyperkinetic conduct disorder in an egalitarian high-income society.

Females with ADHD: An expert consensus statement taking a lifespan approach providing guidance for the identification and treatment of attention-deficit/ hyperactivity disorder in girls and women

BACKGROUND

There is evidence to suggest that the broad discrepancy in the ratio of males to females with diagnosed ADHD is due, at least in part, to lack of recognition and/or referral bias in females. Studies suggest that females with ADHD present with differences in their profile of symptoms, comorbidity and associated functioning compared with males. This consensus aims to provide a better understanding of females with ADHD in order to improve recognition and referral. Comprehensive assessment and appropriate treatment is hoped to enhance longer-term clinical outcomes and patient wellbeing for females with ADHD.

METHODS

The United Kingdom ADHD Partnership hosted a meeting of experts to discuss symptom presentation, triggers for referral, assessment, treatment and multi-agency liaison for females with ADHD across the lifespan.

RESULTS

A consensus was reached offering practical guidance to support medical and mental health practitioners working with females with ADHD. The potential challenges of working with this patient group were identified, as well as specific barriers that may hinder recognition. These included symptomatic differences, gender biases, comorbidities and the compensatory strategies that may mask or overshadow underlying symptoms of ADHD. Furthermore, we determined the broader needs of these patients and considered how multi-agency liaison may provide the support to meet them.

CONCLUSIONS

This practical approach based upon expert consensus will inform effective identification, treatment and support of girls and women with ADHD. It is important to move away from the prevalent perspective that ADHD is a behavioural disorder and attend to the more subtle and/or internalised presentation that is common in females. It is essential to adopt a lifespan model of care to support the complex transitions experienced by females that occur in parallel to change in clinical presentation and social circumstances. Treatment with pharmacological and psychological interventions is expected to have a positive impact leading to increased productivity, decreased resource utilization and most importantly, improved long-term outcomes for girls and women.

Methylmercury, attention, and memory: baseline-dependent effects of adult d-amphetamine and marginal effects of adolescent methylmercury

Methylmercury (MeHg) is an environmental neurotoxicant known to disrupt behavior related to dopamine neurotransmission in experimental models. Such disruptions are sensitive to dopamine agonists when administered acutely after exposure to MeHg has ended or when administered concurrently with MeHg exposure. Sustained attention and short-term remembering, components of attention-deficit/hyperactivity disorder (ADHD), are partially mediated by dopamine neurotransmission. In order to observe MeHg-related alterations in sustained attention and short-term memory, as well as determine sensitivity of MeHg exposed animals to dopamine agonists commonly used in the treatment of ADHD symptoms, rats were exposed to 0, 0.5, or 5 ppm MeHg throughout adolescence and trained in a hybrid sustained attention/short term memory visual signal detection task in adulthood. Behavior was then probed with acute i.p. injections of the dopamine agonist, d-amphetamine, which improves impaired attention and inhibits short-term memory in clinical syndromes like ADHD. Acute d-amphetamine dose-dependently decreased short-term memory as well as sustained attention. While MeHg alone did not impair accuracy or memory, it did interact with d-amphetamine to produce baseline-dependent inhibition of behavior. These findings further show that changes in behavior following low-level exposure to MeHg during adolescence are augmented by dopamine agonists. Observed impairments in memory following acute d-amphetamine are consistent with previous findings.

CDH13 and LPHN3 Gene Polymorphisms in Attention-Deficit/Hyperactivity Disorder: Their Relation to Clinical Characteristics

Genetic factors play a major role in the etiopathogenesis of attention-deficit/hyperactivity disorder (ADHD). In this study, we aimed to investigate the relationship between the CDH13 (rs6565113, rs11150556) and LPHN3 (rs6551665, rs6858066, rs1947274, rs2345039) gene polymorphisms and ADHD. We also sought to examine possible relationships between these polymorphisms and the clinical course and treatment response in ADHD. A total of 120 patients (79% boys), aged 6 to 18 years, newly diagnosed (medication-naïve) with ADHD according to the DSM-5 and a group of 126 controls (74% girls) were enrolled in the study. We examined the association between the aforementioned polymorphisms and ADHD. Univariate and multivariate logistic regression analysis were used to evaluate factors influencing the treatment response of ADHD. A significant difference was found between ADHD and control groups in terms of genotype distribution of the LPHN3 rs6551665 and rs1947274 polymorphisms. The results also showed that having the GG genotype of rs6551665 and CC genotype of rs1947274 of the LPHN3 gene was associated with risk for ADHD, and this relationship was more prominent in male participants. In the multivariate logistic regression model established with variables shown to have a significant relationship with treatment response, the presence of the GG genotype of the LPHN3 rs6551665 polymorphism and high severity of ADHD assessed by CGI-S were associated with poor response to treatment. This study is the first study to investigate the relationship between ADHD and these polymorphisms among Turkish adolescents. Our results imply that the LPHN3 rs6551665 and rs1947274 polymorphisms have a significant effect on ADHD in a Turkish population, and support previous observations that the presence of the GG genotype of the LPHN3 rs6551665 polymorphism may be associated with poor response to treatment in ADHD.

Increased Temporal Lobe Beta Activity in Boys With Attention-Deficit Hyperactivity Disorder by LORETA Analysis

Aim: Attention-deficit hyperactivity disorder (ADHD) is a common childhood neuropsychiatric disorder that affects 6.1 million US children. The mechanism of ADHD is currently unclear. Differences in ADHD presentations between boys and girls are well-established. In the present study, we used quantitative electroencephalography (EEG) to investigate the brain area and EEG bands of boys with ADHD.

Methods: This study enrolled 40 boys with ADHD and 40 age-matched controls without ADHD. Low-resolution electromagnetic tomography (LORETA) and instantaneous frequency were used to analyze EEG data to reveal the mechanisms underlying ADHD in boys.

Results: We found that the instantaneous frequencies in the T3 and T4 EEG channels in boys with ADHD were significantly higher than those in the controls. The beta band showed significant difference in current density between the ADHD and control groups. In the entire brain area, the bilateral inferior and middle temporal gyrus exhibited the most significant difference between the ADHD and control groups in the EEG beta band. Connectivity analysis revealed an increase in connectivity between the left middle frontal gyrus and fusiform gyrus of the temporal lobe in boys with ADHD.

Conclusions: LORETA is a promising tool for analyzing EEG signals and can be used to investigate the mechanism of ADHD. Our results reveal that the inferior temporal gyrus, middle temporal gyrus, and fusiform gyrus of the temporal lobe are potentially involved in the pathogenesis of ADHD in boys. In comparison with other imaging methods, such as magnetic resonance imaging, EEG is easy to perform, fast, and low cost. Our study presents a new approach for investigating the pathogenesis of ADHD in boys.

Investigating gender-specific effects of familial risk for attention-deficit hyperactivity disorder and other neurodevelopmental disorders in the Swedish population

BACKGROUND

Many psychiatric disorders show gender differences in prevalence. Recent studies suggest that female patients diagnosed with anxiety and depression carry more genetic risks related to attention-deficit hyperactivity disorder (ADHD) compared with affected males.

AIMS

In this register-based study, we aimed to test whether female patients who received clinical diagnoses of anxiety, depressive, bipolar and eating disorders are at higher familial risk for ADHD and other neurodevelopmental disorders, compared with diagnosed male patients.

METHOD

We analysed data from a record-linkage of several Swedish national registers, including 151 025 sibling pairs from 103 941 unique index individuals diagnosed with anxiety, depressive, bipolar or eating disorders, as well as data from 646 948 cousin pairs. We compared the likelihood of having a relative diagnosed with ADHD/neurodevelopmental disorders in index males and females.

RESULTS

Female patients with anxiety disorders were more likely than affected males to have a brother with ADHD (odd ratio (OR) = 1.13, 95% CI 1.05-1.22). Results for broader neurodevelopmental disorders were similar and were driven by ADHD diagnoses. Follow-up analyses revealed similar point estimates for several categories of anxiety disorders, with the strongest effect observed for agoraphobia (OR = 1.64, 95% CI 1.12-2.39). No significant associations were found in individuals with depressive, bipolar or eating disorders, or in cousins.

CONCLUSIONS

These results provide modest support for the possibility that familial/genetic risks for ADHD may show gender-specific phenotypic expression. Alternatively, there could be gender-specific biases in diagnoses of anxiety and ADHD. These factors could play a small role in the observed gender differences in prevalence of ADHD and anxiety.

The Use of Sleep Medication in Youth Residential Care

Objectives: To investigate the use of sleep medication and concomitant psychotropic medication in children and adolescents placed under residential care (RC). Methods: Participants were youth 0-20 years of age placed in RC institutions at least once during 2016. Data on filled prescriptions were taken from the Norwegian Prescription Database to compare the use of sleep medication in RC with the general child population (GenPop) and how it covaried with gender, age, reasons for RC placement, and concomitant use of other psychotropic medications (antidepressants, anxiolytics, antipsychotics, and psychostimulants). Results: A total of 2171 youths were identified in RC at mean age 14 years (82% ≥ 13 years). Seventeen percent (371/2171) used sleep medications (melatonin 11%, alimemazine 7%, and benzodiazepines/z-hypnotics 2%) significantly more than the 2.3% who used in GenPop. The girl/boy ratio for medication use in RC was 1.8 (95% confidence interval [CI] = 1.5-2.2), not significantly different from the corresponding ratio in GenPop (1.4; 95% CI = 1.3-1.5). The use of sleep medication increased with age. When comparing reasons for placement in RC, medication use was particularly low among unaccompanied minor asylum seekers (2%). About half of the youths used concomitant psychotropic medication, with clear gender differences; girls used about twice as much antidepressants, anxiolytics, and antipsychotics, whereas boys used 1.3 times more psychostimulants. Conclusion: Youths in RC used more sleep medication and concomitant psychotropic medication than the GenPop, most likely reflecting the increased psychosocial strain and mental disorders reported in this population. Further studies of prevalence, assessment, and treatment of sleep problems in RC populations are warranted.

Emotional Instability Relates to Ventral Striatum Activity During Reward Anticipation in Females

Both non-emotional symptoms, such as inattention, and symptoms of emotional instability (EI) are partially co-varying and normally distributed in the general population. Attention Deficit Hyperactivity Disorder (ADHD), which is associated with both inattention and emotional instability, has been related to lower reward anticipation activation in the ventral striatum. However, it is not known whether non-emotional dysregulation, such as inattention, or EI—or both—are associated with this effect. We hypothesized that altered reward processing relates specifically to EI. To test this, 29 healthy participants were recruited to this functional MRI study (n = 15 females). Reward processing was studied using a modified version of the Monetary Incentive Delay (MID) task. Brown Attention-Deficit Disorder Scales questionnaire was used to assess EI and inattention symptoms on a trait level. We observed less ventral striatal activation during reward anticipation related to the EI trait in females, also when controlling for the inattention trait, but not in the whole sample or males only. Our study suggests the existence of sex differences in the relationship between reward processing and EI/inattention traits.

Sex Differences in Associations between Early Adversity, Child Temperament, and Behavior Problems

Early adversity is associated with both internalizing and externalizing problems among children, and effects of adversity on dimensions of child temperament may underlie these links. However, very little is known about the role of child sex in these processes. The current study examined if there are indirect effects of early adversity on behavior problems through dimensions of child temperament and if these indirect effects vary across child sex. Participants in this multimethod (parent-report survey, semi-structured interview, child protection records) study included 274 preschool-aged children (M _age = 50.86 months; 52% with documented case of moderate-severe maltreatment) and their primary caregivers assessed at two time-points spaced 6 months apart. Results of multi-group path analyses revealed that while anger mediated associations between lifetime stress and behavior problems for the full sample, inhibitory control and appropriate attentional allocation were significant intermediary mechanisms of lifetime stress for boys, but not for girls. Inhibitory control mediated associations between maltreatment and behavior problems for the full sample, but appropriate attentional allocation mediated these associations for boys only. Results suggest that early adversity influences child behavior problems through child temperament, particularly for boys. This work supports the perspective that temperament is influenced by characteristics of the early rearing environment, and the indirect effects of adversity on behavior problems through temperament vary across sex.

Postweaning Iron Deficiency in Male Rats Leads to Long-Term Hyperactivity and Decreased Reelin Gene Expression in the Nucleus Accumbens

BACKGROUND

Epidemiological research indicates that iron deficiency (ID) in infancy correlates with long-term cognitive impairment and behavioral disturbances, despite therapy. However, the mechanisms underlying these effects are unknown.

OBJECTIVE

We investigated how ID affected postweaning behavior and monoamine concentration in rat brains to determine whether ID during the juvenile period affected gene expression and synapse formation in the prefrontal cortex (PFC) and nucleus accumbens (NAcc).

METHODS

Fischer 344/Jcl postweaning male rats aged 21-39 d were fed low-iron diets (0.35 mg/kg iron; ID group) or standard AIN-93 G diets [3.5 mg/kg iron; control (CN) group]. After day 39, all rats were fed the iron-adequate diet. The locomotor activity was evaluated by the open field and elevated plus maze tests at 8 and 12 wk of age. Monoamine concentrations in the brain were analyzed using HPLC at 9 and 13 wk of age. Comprehensive gene expression analysis was performed in the PFC and NAcc at 13 wk of age. Finally, we investigated synaptic density in the PFC and NAcc by synaptophysin immunostaining.

RESULTS

Behavioral tests revealed a significant reduction of the age-related decline in the total distance traveled in ID rats compared with CN rats (P < 0.05), indicating that ID affected hyperactivity, which persisted into adulthood (13 wk of age). At this age, reelin (Reln) mRNA expression (adjusted P < 0.01) decreased and synaptic density (P < 0.01) increased in the NAcc in the ID group. Regarding the mesolimbic pathway, homovanillic acid concentration increased in the NAcc, whereas the dopamine concentration decreased in the ventral midbrain.

CONCLUSIONS

Our results suggest that ID during the postweaning period in male rats, despite complete iron repletion following ID, led to long-term hyperactivity via monoamine disturbance in the brain and an alteration in the synaptic plasticity accompanied by downregulation of Reln expression in the NAcc.

Gender Differences in Objective and Subjective Measures of ADHD Among Clinic-Referred Children

Attention deficit hyperactivity disorder (ADHD), one of the most prevalent childhood disorders today, is generally more likely to be diagnosed and treated in boys than in girls. However, gender differences in ADHD are currently poorly understood, partly because previous research included only a limited proportion of girls and relied mainly on subjective measures of ADHD, which are highly vulnerable to reporter's bias. To further examine gender differences in ADHD and to address some of the shortcomings of previous studies, this study examined gender differences in subjective and objective measures of ADHD among clinic-referred children with ADHD. Participants were 204 children aged 6-17 years-old with ADHD (129 boys, 75 girls). A retrospective analysis was conducted using records of a clinical database. Obtained data included parent and teacher forms of the Conners ADHD rating scales, Child Behavior Checklist (CBCL), Teacher's Report Form (TRF), and child's continuous performance test (CPT) scores. Results showed that according to parents' and teachers' reports of ADHD-related symptoms (Conners ADHD rating scales), girls had more inattention problems than boys, but no differences were identified in the level of hyperactivity and impulsivity symptoms. CPT data, however, revealed higher impulsivity among boys. We did not find gender differences in the level of distractibility during CPT performance. Specifically, the effects of distractors type (visual environmental stimuli, auditory stimuli, or a combination of them) and distractors load (one or two distracting stimuli at a time) on CPT performance did not differ between boys and girls with ADHD. These findings suggest that gender effects on ADHD symptoms may differ between subjective and objective measures. Understanding gender differences in ADHD may lead to improved identification of girls with the disorder, helping to reduce the gender gap in diagnosis and treatment.

Resumption of attention-deficit hyperactivity disorder medication in early adulthood: findings from a UK primary care prescribing study

This study aimed to examine the resumption of attention-deficit hyperactivity disorder (ADHD) prescriptions in early adulthood in young people whose ADHD prescriptions stopped in adolescence. Whilst prescribing studies indicate that the proportion of those with ADHD stopping treatment in late adolescence remains in excess of the proportion expected to be symptom free, very few studies have examined patterns of resumption amongst young adults previously prescribed medication. Primary care records from the UK Clinical Practice Research Datalink from 2008 to 2013 were used to examine the outcome of resumption of ADHD prescriptions from age 20 years in a sample of cases with ADHD whose prescriptions stopped aged 14-18 years. A Cox regression model was fitted to explore variables that could theoretically be associated with resumption of prescriptions. Of 1440 cases, 109 (7.6%) had their ADHD prescriptions resumed. Characteristics associated with an increased probability of resumption included female gender, learning disability, referral to adult mental health services, and prescription of antipsychotic medication. In this study, only a small proportion of adolescents who stopped ADHD medication subsequently resumed their prescriptions in primary care. Those that did resume were a more complex group. As many vulnerable individuals with ongoing ADHD symptoms may not have the resources required to surmount the barriers to re-enter services, the implication is that not all those who could benefit from resuming medication are able to do so. The findings raise questions around whether current care models are flexible enough and whether primary care services are adequately supported in managing this group.

Factors Associated with Attention Deficit Hyperactivity Disorder Medication Use in Community Care Settings

OBJECTIVES

To examine patient- and provider-level factors associated with receiving attention-deficit/hyperactivity disorder (ADHD) medication treatment in a community care setting. We hypothesized that the likelihood of ADHD medication receipt would be lower in groups with specific patient sociodemographic (eg, female sex, race other than white) and clinical (eg, comorbid conditions) characteristics as well as physician characteristics (eg, older age, more years since completing training).

STUDY DESIGN

A retrospective cohort study was conducted with 577 children (mean age, 7.8 years; 70% male) presenting for ADHD to 50 community-based practices. The bivariate relationship between each patient- and physician-level predictor and whether the child was prescribed ADHD medication was assessed. A multivariable model predicting ADHD medication prescription was conducted using predictors with significant (P < .05) bivariate associations.

RESULTS

Sixty-nine percent of children were prescribed ADHD medication in the year after initial presentation for ADHD-related concerns. Eleven of 31 predictors demonstrated a significant (P < .05) bivariate relationship with medication prescription. In the multivariable model, being male (OR, 1.34; 95% CI, 1.01-1.78; P = .02), living in a neighborhood with higher medical expenditures (OR, 1.11 for every $100 increase; 95% CI, 1.03-1.21; P = .005), and higher scores on parent inattention ratings (OR, 1.06; 95% CI, 1.03-1.10; P < .0001) increased the likelihood of ADHD medication prescription.

CONCLUSIONS

We found that some children, based on sociodemographic and clinical characteristics, are less likely to receive an ADHD medication prescription. An important next step will be to examine the source and reasons for these disparities in an effort to develop strategies for minimizing treatment barriers.

Genetic Variation Underpinning ADHD Risk in a Caribbean Community

Attention Deficit Hyperactivity Disorder (ADHD) is a highly heritable and prevalent neurodevelopmental disorder that frequently persists into adulthood. Strong evidence from genetic studies indicates that single nucleotide polymorphisms (SNPs) harboured in the ADGRL3 (LPHN3), SNAP25, FGF1, DRD4, and SLC6A2 genes are associated with ADHD. We genotyped 26 SNPs harboured in genes previously reported to be associated with ADHD and evaluated their potential association in 386 individuals belonging to 113 nuclear families from a Caribbean community in Barranquilla, Colombia, using family-based association tests. SNPs rs362990-SNAP25 (T allele; p = 2.46 × 10⁻⁴), rs2282794-FGF1 (A allele; p = 1.33 × 10⁻²), rs2122642-ADGRL3 (C allele, p = 3.5 × 10⁻²), and ADGRL3 haplotype CCC (markers rs1565902-rs10001410-rs2122642, OR = 1.74, P_permuted = 0.021) were significantly associated with ADHD. Our results confirm the susceptibility to ADHD conferred by SNAP25, FGF1, and ADGRL3 variants in a community with a significant African American component, and provide evidence supporting the existence of specific patterns of genetic stratification underpinning the susceptibility to ADHD. Knowledge of population genetics is crucial to define risk and predict susceptibility to disease.

Evaluating a scale of excessive mind wandering among males and females with and without attention-deficit/hyperactivity disorder from a population sample

Recent studies highlight the role of excessive mind wandering in attention-deficit/hyperactivity disorder (ADHD) and its association with impairment. We believe assessing mind wandering could be especially relevant to individuals, including many females, who present with less externalising manifestations of ADHD. Using a new measure based on ADHD patient reports, the Mind Excessively Wandering Scale (MEWS), we previously found adults with ADHD had elevated levels of mind wandering that contributed to impairment independently of core ADHD symptoms. Using data from an online general population survey, the current study assessed the factor-structure, reliability, validity and measurement invariance of the MEWS. We also investigated sex differences in mind wandering, as well as ADHD symptoms, impairment and wellbeing in those with and without ADHD. The MEWS had a unidimensional structure, was invariant across sex, age and ADHD status, and accounted for unique variance in impairment and wellbeing beyond core ADHD symptoms. Among those with ADHD, we found no evidence for sex differences in mind wandering and among those without ADHD males had higher scores. We also found similar levels of hyperactivity/impulsivity, emotional lability, and impairment in males and females with ADHD, but males reported greater inattention and lower wellbeing. Results suggest the MEWS is a reliable and valid instrument measuring the same construct across sex, age and ADHD status, which could aid diagnosis and monitoring of outcomes.

Sex-Gender Comparisons in Comorbidities of Children and Adolescents With High-Functioning Autism Spectrum Disorder

Over the last few years, new studies focused their attention on the gender-related features in high-functioning autism spectrum disorder (HFA), often leading to controversial results. Another interesting aspect of these subtype of patients is linked to the complexity of clinical presentation, where besides core symptoms, other co-occurrence disorders may complicate the diagnostic evaluation. Therefore, we retrospectively studied 159 HFA patients, male and female, investigating their comorbidities and to find any gender difference. For each patient, were evaluated the presence/absence, type and gender distribution of psychopathological comorbidities, according to DSM-5 diagnostic criteria. The total sample was divided in 100 male and 59 female patients, age and intelligence quotient matched. In our sample, the psychiatric comorbidities observed were Attention Deficit Hyperactivity Disorder, Anxiety Disorders, Depressive Disorders, Bipolar Disorder, Obsessive-Compulsive Disorder, and Anorexia Nervosa. No statistical significant differences were found between male and female HFA patients comorbidities except for Anorexia Nervosa. In both male and female patients, attention deficit and hyperactivity disorder and anxiety disorders were found in high percentage. In conclusion, our investigation showed that a statistical significant difference of comorbidity between male and female HFA patients was found only for AN diagnosis. However, the question about the distinction between female and male HFA patients remains quite interesting and an open area of research for future studies.