Lynda M. Paton

Effect of antiepileptic medication on bone mineral measures

Objective: Long-term antiepileptic drug (AED) use has been associated with bone disease, but many previous studies have been limited by inadequate control subjects. We used a cotwin affected sib-pair model to investigate this issue. Methods: The authors studied 31 female twin (15 monozygous and 16 dizygous) and four sibling pairs (<3 years age difference) aged 21 to 75 years, in which one member had >12 months of AED treatment. Areal bone mineral density (ABMD, g/cm2) was measured at the lumbar spine (LS), total hip (TH), femoral neck (FN), and total forearm (FA). Three primary a priori defined subgroups were analyzed: a) use for >2 years, b) use of enzyme-inducing AEDs, or c) age older than 40 years. Results: For all pairs (n = 35), there were no significant within-pair differences in any ABMD measure. However, in Subgroup a (n = 27), there was a within-pair difference at the FA (0.513 vs 0.534, −3.9%, p = 0.016). In Subgroup b (n = 29), there was also a within-pair difference at the FA for AED user vs nonuser (0.508 vs 0.529, −3.8%, p = 0.010). In Subgroup c (n = 15), there were within-pair differences at the FA (0.492 vs 0.524, −6.1%, p = 0.017) and the LS (0.884 vs 0.980, −9.8%, p = 0.036). Conclusions: Patients using AEDs for >2 years, in particular those taking enzyme-inducing AEDs and those older than 40 years, have significantly lower bone mineral density at clinically relevant fracture risk sites.

Determinants of bone density in 30- to 65-year-old women: A co-twin study

Reported effects of body composition and lifestyle on bone mineral density in pre‐elderly adult women have been inconsistent. In a co‐twin study, we measured bone mineral density, lean and fat mass, and lifestyle factors. Analyzing within pair differences, we found negative associations between bone mineral density and tobacco use (2.3–3.3% per 10 pack‐years) and positive associations with sporting activity and lean and fat mass.

Relationships with serum parathyroid hormone in old institutionalized subjects

OBJECTIVE and BACKGROUND Old people in residential care are at the highest risk of any group for hip fracture. This may relate to their high prevalence of hyperparathyroidism. There are few data, however, on relationships with serum parathyroid hormone (PTH) in these individuals. This study therefore examined complex associations with serum PTH in nursing home and hostel residents.

Balance impairment in chronic antiepileptic drug users: A twin and sibling study

Purpose:  Patients taking antiepileptic drugs (AEDs) have an increased incidence of fractures. This study investigated chronic AED use and physical contributors to falls risk using an AED‐discordant, twin and sibling matched‐pair approach, and assessed clinically relevant subgroups: AED polytherapy; longer‐duration AED; and falls history.

Association of Birth Weight and Current Body Size to Blood Pressure in Female Twins

It has been proposed that low birth weight is associated with high levels of blood pressure in later life. The aim of this study was to assess the relationship of blood pressure to birth weight and current body size during growth and adulthood. A total of 711 female multiple births, with one group of 244 in their growth phase mean age 12.0 (2.3)(SD) years and the other of 467 adults (mean age 35.2 (12.6) years), had height, weight and both systolic (SBP) and diastolic (DBP) blood pressures measured, and self-reported their birth weight. Regression analyses were performed to assess the cross-sectional and within-pair associations of blood pressure to birth weight, with and without adjustments for current body size. Within-pair analysis was based on 296 twin pairs. Cross-sectionally, a reduction in birth weight of 1 kg was associated with 2 to 3 mm Hg higher age-adjusted SBP, which was of marginal significance and explained about 2% of the population variance. Adjustment for body mass index did not significantly change this association. Within-pair analyses found no association between birth weight and SBP or DBP,even after adjusting for current body size. After age, current body size was the strongest predictor of systolic BP. The weak association of blood pressure to birth weight cross-sectionally is of interest, but any within-pair effect of birth weight on blood pressure must be minimal compared with the effect of current body size.

Hormone replacement therapy and bone mineral density: a co-twin approach.

ObjectiveOur objective was to estimate the difference in bone mass at clinically relevant sites within female twin pairs who were discordant for use of hormone replacement therapy (HRT). MethodsWe studied 46 female twin pairs who were discordant for HRT use. Bone mineral content and density were measured at the lumbar spine, total hip, femoral neck, 13total forearm, and the total body. HRT use, calcium intake, physical activity, alcohol intake, and lifetime smoking were determined by questionnaire. ResultsWithin a pair, lumbar spine bone mineral density was significantly greater in past and current HRT users compared with nonusers (6.2% ± 2.0%;P = 0.006). In those pairs who were currently using HRT, the within-pair difference in lumbar spine bone density was 7.8% ± 2.1% (P = 0.002), and a significant within-pair difference in forearm bone density (5.1 ± 2.1%;P = 0.02) was apparent. A significant difference (4.6%;P = 0.03) was observed in total body bone mineral content when an adjustment was made for age, lean mass, fat mass, and height. ConclusionsIn keeping with randomized clinical trial findings, these results indicate that HRT in routine clinical use protects significantly against menopausal bone loss at the lumbar spine and the forearm. Our results also quantify the magnitude of the benefit of HRT on bone density that might be anticipated in clinical practice.