The Effect of Previous Methylphenidate Use on Incidence of Stress Fractures in Military Recruits: A Retrospective Cohort

The Effects of Chronic Psychostimulant Administration on Bone Health: A Review

(1) Background: Methylphenidate (MP) and amphetamine (AMP) are psychostimulants that are widely prescribed to treat Attention Deficit Hyperactivity Disorder (ADHD) and narcolepsy. In recent years, 6.1 million children received an ADHD diagnosis, and nearly 2/3 of these children were prescribed psychostimulants for treatment. The purpose of this review is to summarize the current literature on psychostimulant use and the resulting effects on bone homeostasis, biomechanical properties, and functional integrity. (2) Methods: Literature searches were conducted from Medline/PubMed electronic databases utilizing the search terms "methylphenidate" OR "amphetamine" OR "methylphenidate" AND "bone health" AND "bone remodeling" AND "osteoclast" AND "osteoblast" AND "dopamine" from 01/1985 to 04/2023. (3) Results: Of the 550 publications found, 44 met the inclusion criteria. Data from identified studies demonstrate that the use of MP and AMP results in decreases in specific bone properties and biomechanical integrity via downstream effects on osteoblasts and osteoclast-related genes. (4) Conclusions: The chronic use of psychostimulants negatively affects bone integrity and strength as a result of increased osteoclast activity. These data support the need to take this into consideration when planning the treatment type and duration for bone fractures.

Methylphenidate use and restorative treatment needs in young adults with attention deficit hyperactivity disorder

OBJECTIVE

To assess the effect and dose-response of methylphenidate (MP) use on the restorative treatment needs in young adults with attention deficit hyperactivity disorder.

PARTICIPANTS AND METHODS

This retrospective study comprises a cohort of military recruits aged 18-25 who served for 12 to 48 months between 2005 and 2017. The medical records of 213 604 participants were assessed of which: 6875 participants with ADHD who received treatment with MP, 6729 participants with ADHD who had no prescriptions for MP, and 200 000 healthy participants. The outcome was restorative treatment needs, which served as an indicator of caries: having at least one prescription for restorative treatment during the study period.

RESULTS

Frequency of prescription for restorative treatment among the treated, the untreated and the control groups was 24%, 22%, and 17%, respectively (p < .0001). On multivariate analysis, the dose-response association between MP use and the odds of having at least one restorative treatment was confirmed (OR = 1.006 for each additional 1 gr of MP; 95% CI [1.004:1.009]) CONCLUSIONS: Participants with ADHD who receive chronic treatment with MP have higher restorative treatment needs than participants with untreated ADHD and healthy participants. Our results show that chronic MP medication among young adults leads to an elevated need for restorative treatment and implies a significant impact on oral health (OH).

Circulating MiRNA-21-enriched extracellular vesicles promote bone remodeling in traumatic brain injury patients

Fracture combined with traumatic brain injury (TBI) is one of the most common and serious types of compound trauma in the clinic and is characterized by dysfunction of cellular communication in injured organs. Our prior studies found that TBI was capable of enhancing fracture healing in a paracrine manner. Exosomes (Exos), as small extracellular vesicles, are important paracrine vehicles for noncell therapy. However, whether circulating Exos derived from TBI patients (TBI-Exos) regulate the prohealing effects of fractures remains unclear. Thus, the present study aimed to explore the biological effects of TBI-Exos on fracture healing and reveal the potential molecular mechanism. TBI-Exos were isolated by ultracentrifugation, and the enriched miR-21-5 p was identified by qRT‒PCR analysis. The beneficial effects of TBI-Exos on osteoblastic differentiation and bone remodeling were determined by a series of in vitro assays. Bioinformatics analyses were conducted to identify the potential downstream mechanisms of the regulatory effect of TBI-Exos on osteoblasts. Furthermore, the role of the potential signaling pathway of TBI-Exos in mediating the osteoblastic activity of osteoblasts was assessed. Subsequently, a murine fracture model was established, and the effect of TBI-Exos on bone modeling was demonstrated in vivo. TBI-Exos can be internalized by osteoblasts, and in vitro, suppression of SMAD7 promoted osteogenic differentiation, whereas knockdown of miR-21-5 p in TBI-Exos strongly inhibited this bone-beneficial effect. Similarly, our results confirmed that preinjection of TBI-Exos led to enhanced bone formation, whereas knockdown of exosomal miR-21-5 p substantially impaired this bone-beneficial effect in vivo.

Effects of methylphenidate on femoral bone growth in male rats

The use of Methylphenidate (MP) can have adverse effects on bone growth and mineralization. This study aimed to investigate the underlying pathophysiology of MP-induced skeletal deficits in growing rats using stereological and immunohistochemical methods. Male rats, aged 4 weeks, were orally treated with MP through an 8-h/day water drinking protocol. The rats (n=30) were randomly divided into three groups: MP-High Dose (30/60 mg/kg/day MP), MP-Low Dose (4/10 mg/kg/day MP), and control (water only). After 13 weeks, the femoral bones were assessed using calliper measurements, dual-energy X-ray absorptiometry, and biomechanical evaluation. The total femur volume, cartilage volume, growth zone volume, and volume fractions were determined using the Cavalieri method. Immunohistochemical analyses were conducted using alkaline phosphatase and anti-calpain antibody staining. Rats exposed to MP exhibited significant reductions in weight gain, femoral growth, bone mineralization, and biomechanical integrity compared to the control group. The total femoral volume of MP-treated rats was significantly lower than that of the control group. The MP-High Dose group showed significantly higher ratios of total cartilage volume/total femoral volume and total growth zone volume/total femoral volume than the other groups. Immunohistochemical evaluation of the growth plate revealed reduced osteoblastic activity and decreased intracellular calcium deposition with chronic MP exposure. The possible mechanism of MP-induced skeletal growth retardation may involve the inhibition of intracellular calcium deposition in chondrocytes of the hypertrophic zone in the growth plate. In this way, MP may hinder the differentiation of cartilage tissue from bone tissue, resulting in reduced bone growth and mineralization.

Chondral/Desmal Osteogenesis in 3D Spheroids Sensitized by Psychostimulants

Attention deficit hyperactivity disorder (ADHD) affects 6.4 million children in the United States of America. Children and adolescents, the main consumers of ADHD medication, are in the bone growth phase, which extends over a period of up to two decades. Thus, impaired proliferation and maturation of chondrocytes and osteoblasts can result in impaired bone formation. The aim of this study is to investigate, for the first time, the effects of the ADHD-medication modafinil, atomoxetine and guanfacine on bone growth and repair in vitro. Using two-dimensional and three-dimensional cell models, we investigated the chondrogenic/osteogenic differentiation, proliferation and viability of human mesenchymal progenitor cells. Real-time cell proliferation was measured by xCELLigence. Live/dead staining and size measurement of hMSC- and MG63 monolayer and spheroids were performed after administration of therapeutic plasma concentrations of modafinil, atomoxetine and guanfacine. Chondrogenic differentiation was quantified by RTqPCR. The chondrogenic and osteogenic differentiation was evaluated by histological cryo-sections. Modafinil, atomoxetine and guanfacine reduced chondrogenic and osteogenic differentiation terms of transcript expression and at the histological level. Cell viability of the MG63- and hMSC monolayer was not impeded by ADHD-medication. Our in vitro results indicate that modafinil, atomoxetine and guanfacine may impair chondrogenic and osteogenic differentiation in a 3D model reflecting the in vivo physiologic condition.

Psychostimulants Modafinil, Atomoxetine and Guanfacine Impair Bone Cell Differentiation and MSC Migration

Attention deficit hyperactivity disorder (ADHD) is one of the most common worldwide mental disorders in children, young and adults. If left untreated, the disorder can continue into adulthood. The abuse of ADHD-related drugs to improve mental performance for studying, working and everyday life is also rising. The potentially high number of subjects with controlled or uncontrolled use of such substances increases the impact of possible side effects. It has been shown before that the early ADHD drug methylphenidate influences bone metabolism negatively. This study focused on the influence of three more recent cognitive enhancers, modafinil, atomoxetine and guanfacine, on the differentiation of mesenchymal stem cells to osteoblasts and on their cell functions, including migration. Human mesenchymal stem cells (hMSCs) were incubated with a therapeutic plasma dosage of modafinil, atomoxetine and guanfacine. Gene expression analyses revealed a high beta-2 adrenoreceptor expression in hMSC, suggesting it as a possible pathway to stimulate action. In bone formation assays, all three cognitive enhancers caused a significant decrease in the mineralized matrix and an early slight reduction of cell viability without triggering apoptosis or necrosis. While there was no effect of the three substances on early differentiation, they showed differing effects on the expression of osterix (OSX), receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) in the later stages of osteoblast development, suggesting alternative modes of action. All three substances significantly inhibited hMSC migration. This effect could be rescued by a selective beta-blocker (Imperial Chemical Industries ICI-118,551) in modafinil and atomoxetine, suggesting mediation via beta-2 receptor stimulation. In conclusion, modafinil, atomoxetine and guanfacine negatively influence hMSC differentiation to bone-forming osteoblasts and cell migration through different intracellular pathways.

Effect of methylphenidate at different doses on new bone formation with rapid maxillary expansion: A micro-CT and histomorphometric study in rats

OBJECTIVES

This study aimed to evaluate the effect of systemically administered methylphenidate hydrochloride (MPH) on new bone formation in premaxillary suture after rapid maxillary expansion (RME).

SETTING AND SAMPLE POPULATION

Thirty-three Wistar rats were divided into four groups: Group 1 (high dose, 30/60 mg/kg MPH), Group 2 (low dose, 4/10 mg/kg MPH), Group 3 (positive control) and Group 4 (negative control).

METHODS

RME was applied on the 70th day of the study. A 5-day RME period was followed by a 12-day retention period. The experiment was terminated on the 87th day. Micro-CT for radiological evaluation, haematoxylin-eosin and Masson's trichrome staining methods were used for histomorphometric evaluation.

RESULTS

Among experimental groups with RME, the lowest number of osteoblasts and capillaries in Group 1 (P < .05). New bone formation, fibrous callus formation, distal osteotomy line, proximal osteotomy union and cortex remodelling were observed to be lower in Group 1 and Group 2 than Group 3 (P < .05). There was a statistically significant difference between Group 4 and each of the other groups (P = .000) in the evaluation of the results for bone mineral density, bone volume, bone volume percentage, trabecular thickness and trabecular number.

CONCLUSIONS

MPH reduces cellular activity for new bone formation in suture in RME groups. Before performing rapid maxillary expansion in patients using MPH, the use of the drug should be postponed after a multidisciplinary decision process or clinical doses should be lowered.

Musculoskeletal Injuries Among Females in the Military: A Scoping Review

INTRODUCTION

Musculoskeletal injuries (MSKi) are a common challenge for those in military careers. Compared to their male peers, reports indicate that female military members and recruits are at greater risk of suffering MSKi during training and deployment. The objectives of this study were to identify the types and causes of MSKi among female military personnel and to explore the various risk factors associated with MSKi.

MATERIALS AND METHODS

A scoping review was conducted over a 4-month time frame of English language, peer-reviewed studies published from 1946 to 2019. Search strategies for major biomedical databases (e.g., MEDLINE; Embase Classic + Embase; and the following EBM Reviews-Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Health Technology Assessment, and the NHS Economic Evaluation Database) were developed by a senior medical information specialist and included 2,891 titles/abstracts. Study selection and data collection were designed according to the Population, Concept, and Context framework. Studies were included if the study population provided stratified data for females in a military context.

RESULTS

From a total of 2,287 citations captured from the literature searches, 168 peer-reviewed publications (144 unique studies) were eligible for inclusion. Studies were identified from across 10 countries and published between 1977 and 2019. Study designs were primarily prospective and retrospective cohorts. Most studies assessed both prevalence/incidence and risk factors for MSKi (62.50%), with few studies assessing cause (13.69%). For MSKi of female recruits compared to active female members, the prevalence was higher (19.7%-58.3% vs. 5.5%-56.6%), but the incidence (0.02%-57.7% vs. 13.5%-71.9%) was lower. The incidence of stress fractures was found to be much higher in female recruits than in active members (1.6%-23.9% vs. 2.7%). For anthropometric risk factors, increased body fat was a predictor of MSKi, but not stress fractures. For physiological risk factors for both female military groups, being less physically fit, later menarche, and having no/irregular menses were predictors of MSKi and stress fractures. For biomechanical risk factors, among female recruits, longer tibial length and femoral neck diameter increased the risk of stress fractures, and low foot arch increased risk of an ankle sprain. For female active military members, differences in shoulder rotation and bone strength were associated with risk of MSKi. For biological sex, being female compared to male was associated with an increased risk of MSKi, stress fractures, and general injuries. The consequences of experiencing MSKi for active military included limited duties, time off, and discharge. For recruits, these included missed training days, limited duty days, and release.

CONCLUSIONS

This scoping review provides insight into the current state of the evidence regarding the types and causes of MSKi, as well as the factors that influence MSKi among females in the military. Future research endeavors should focus on randomized controlled trials examining training paradigms to see if women are more susceptible. The data presented in the scoping review could potentially be used to develop training strategies to mitigate some of the identified barriers that negatively impact women from pursuing careers in the military.

ADHD, stimulant medication use, and the risk of fracture: a systematic review and meta-analysis

We performed a meta-analysis to quantify the relationships among a diagnosis of attention-deficit/hyperactivity disorder (ADHD), the use of stimulant medication, and the risk of fracture. There was a significant positive association between ADHD and the risk of fracture. However, stimulant ADHD medication therapy appears to be associated with a reduced risk of fracture in patients with ADHD.

INTRODUCTION

ADHD is associated with an increased fracture risk due to a lack of impulse control. ADHD medication may have a protective effect via behavior modification. However, previous research found an adverse effect of stimulant use on bone mass. Therefore, this meta-analysis study assessed the relationships among ADHD, the use of stimulant medication, and fracture risk.

METHODS

A literature search was conducted using PubMed and EMBASE from inception through December 2020. Random-effects models were used to determine overall pooled estimates and 95% confidence intervals (CIs).

RESULTS

The meta-analysis included 10 observational studies. Our results showed that ADHD diagnosis is associated with an increased risk of fracture (OR = 1.17; 1.01-1.35, p = 0.035). Notably, a higher risk of fracture (OR = 1.37, 95% CI 1.2-1.58, p < 0.001) was observed in non-stimulant-treated ADHD. However, no significant association, but a trend toward a lower risk, was observed for stimulant-treated ADHD patients compared with non-stimulant-treated ADHD patients (OR = 0.7, 95% CI 0.47-1.03, p = 0.073). In terms of fracture type, non-stimulant-treated ADHD was associated with traumatic fracture (OR = 1.79, 95% CI 1.54-2.08, p < 0.001) or stress fracture (OR = 1.12, 95% CI 1.04-1.2, p = 0.004) compared to healthy control (HC). In addition, further findings from our systematic review showed that the risk of traumatic (OR = 1, 95% CI 0.88-1.13, p = 0.954) or stress (OR = 0.84, 95% CI 0.62-1.14, p = 0.256) fracture was comparable between treated stimulant-ADHD patients and HC.

CONCLUSIONS

Individuals with ADHD are at higher risk of fracture than the general population. Stimulant ADHD medication appears to be associated with a lower risk of traumatic fracture but not with a higher risk of stress fracture.

The effects of methylphenidate on stress fractures in patients' ages 10-29: a national database study

Objectives: Current literature is divided on the effect of methylphenidate (MP) on stress fracture development and if this medication increases fracture, or is actually protective for it. This study further investigates this effect utilizing a large national database. We hypothesized that individuals on MP would have a reduced risk of SF compared against controls. Methods: This study utilized the Humana insurance data set within the PearlDiver Patient Records Database (PearlDiver Inc, Fort Wayne, Indiana). All patients' ages 10-29 were included and patients were identified without ADHD, with ADHD not on MP, and with ADHD on MP. ADHD and stress fracture diagnoses were identified by International Classification of Disease, Tenth Revision codes. Bivariate analysis of stress fracture occurrence was conducted using chi-square analysis. Multivariate logistic regression was used to calculate odds ratios, controlling for age, sex, race, and Charlson Comorbidity Index (CCI). Statistical analysis was performed using the PearlDiver software, which runs R, Version 1.1.442. An α value of .05 was set as the level of significance. Results: The study included 29,590 patients on MP and 831,439 patients not on MP from ages 10-29. The highest proportions of patients who filled MP prescriptions were in the age range 10 to 14 years old (51.2%), followed by 15 to 19 (41.0%). Patients rarely continue MP from years 20 to 24 (16.5%) or 25 to 29 (9.6%). ADHD patients on MP had the lowest calculated risk of stress fractures (0.45%) compared to patients without ADHD (0.54%) and ADHD patients not on methylphenidate (0.58%). In all three patient groups, most stress fractures occurred in 15 to 19-year olds. Patients with ADHD on MP conferred lower odds of stress fracture than ADHD patients not on MP and patients without ADHD (aOR = 0.64, p = 0.0002). The older age groups 20-24 and 25-29 involved less risk of stress fracture compared to the youngest age group 10-14 (p < 0.0001; p < 0.0001), as well as did male gender (p < 0.0001). Conclusions: This database-based study of the effect of MP on SF adds to the growing body of literature providing evidence that MP may offer protective benefit for stress fracture.

Lower risk of stress fractures in young adults with ADHD under chronic treatment with methylphenidate

INTRODUCTION

Methylphenidate (MP) use is highly prevalent among children and young adults. Previous basic and epidemiological research demonstrated an adverse effect of MP on bone mass. Studies in military recruits have shown that history of MP use before conscription was a risk factor for stress fractures (SF) during the service.

METHODS

This study is part of the project in which the association between MP use and incidence of SF was retrospectively investigated in a cohort of healthy conscripts aged 18-25, who served for at least 12 months between 2008 and 2017. Baseline information included sex, age, weight, height, geographic origin, socioeconomic status, and education. Subjects were divided into five groups: subjects without ADHD; untreated subjects with ADHD; and subjects with ADHD and prescriptions of 1-90, 91-180, or 181+ tablets during the study period. The primary outcome was at least one diagnosis of stress fracture during the study.

RESULTS

Among 682,110 subjects (409,175 men [60%]), 29,888 (4.4%) had fractures. MP was used by 1681 (0.4%) men and 2828 (1%) women. In both men and women, SF incidence was significantly higher among subjects with untreated ADHD (7.9% and 5.4%, respectively) and significantly lower in subjects with treated ADHD (1.9-3%; 0.3-4.3%), compared to healthy controls (5.3% and 2.9%). After multivariate adjustment, subjects with untreated ADHD remained at an increased risk of fracture (men OR = 1.66, p < 0.001 and women OR = 1.33, p = 0.007), whereas only subjects with highest exposure to MP (180+ tablets) had significantly lower chances for fracture (men OR = 0.49, p = 0.08 and women OR = 0.09, p = 0.02), compared to healthy controls.

DISCUSSION

The study has demonstrated lower risk of stress fractures with concurrent MP use. The findings in this population challenge our understanding of the MP effect on bone integrity and prompt further basic research.

Lower risk of fractures under methylphenidate treatment for ADHD: A dose-response effect

Methylphenidate (MP), a widely used and abused stimulant medication for ADHD, negatively affects bone mass. However, previous epidemiological studies demonstrated that MP is not associated with increased incidence of fractures in children, and may even have a protective effect due to behavior modification. This study aimed to investigate the association between MP and fracture risk in a retrospective cohort of healthy military recruits, aged 18-25, with at least 1 year of service between 2008 and 2017. Subjects were divided into five groups: subjects without ADHD; untreated subjects with ADHD; and subjects with ADHD and prescriptions of 1-90, 91-180, or 181+ tablets during the study period. The primary outcome was at least one fracture diagnosis during the study. Among 682,110 subjects (409,175 men [60%]), 50,999 (7.5%) had fractures. MP was used by 1,681 (0.4%) men and 2.828 (1%) women. The fracture rates in the no ADHD, untreated ADHD, ADHD 0-90, ADHD 91-180, and ADHD 181+ groups were 10.4%, 16.4%, 8.7%, 4.8% and 5.8% in men, and 3.6%, 7.1%, 4.6%, 4.4% and 3% in women, respectively. Multivariate regression analysis confirmed an inverse dose-response association between MP and fractures in men (p < 0.001). In women, untreated ADHD was associated with a significantly higher fracture risk, compared to healthy controls (OR = 1.82, p < 0.001). The study confirms previous literature and demonstrates an inverse dose-response association between MP and fracture risk in men. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3328-3333, 2018.