Psychotropic drugs have contrasting skeletal effects that are independent of their effects on physical activity levels.

Popular psychotropic drugs, like the antidepressant selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs), and the mood stabilizer lithium, may have skeletal effects. In particular, preclinical observations suggest a direct negative effect of SSRIs on the skeleton. A potential caveat in studies of the skeletal effects of psychotropic drugs is the hypoactive (skeletal unloading) phenotype they induce. The aim of this study was to investigate the contribution of physical inactivity to the skeletal effects of psychotropic drugs by studying bone changes in cage control and tail suspended mice treated with either vehicle, SSRI, TCA or lithium. Tail suspension was used to control for drug differences on physical activity levels by normalizing skeletal loading between groups. The psychotropic drugs were found to have contrasting skeletal effects which were independent of drug effects on animal physical activity levels. The latter was evident by an absence of statistical interactions between the activity and drug groups. Pharmacological inhibition of the 5-hydroxytryptamine (5-HT) transporter (5-HTT) using a SSRI reduced in vivo gains in lower extremity BMD, and negatively altered ex vivo measures of femoral and spinal bone density, architecture and mechanical properties. These effects were mediated by a decrease in bone formation without a change in bone resorption suggesting that the SSRI had anti-anabolic skeletal effects. In contrast, glycogen synthase kinase-3[beta] (GSK-3[beta]) inhibition using lithium had anabolic effects improving in vivo gains in BMD via an increase in bone formation, while TCA-mediated inhibition of the norepinephrine transporter had minimal skeletal effect. The observed negative skeletal effect of 5-HTT inhibition, combined with recent findings of direct and indirect effects of 5-HT on bone formation, are of interest given the frequent prescription of SSRIs for the treatment of depression and other affective disorders. Likewise, the anabolic effect of GSK-3[beta] inhibition using lithium reconfirms the importance of Wnt/beta-catenin signaling in the skeleton and it's targeting by recent drug discovery efforts. In conclusion, the current study demonstrates that different psychotropic drugs with differing underlying mechanisms of action have contrasting skeletal effects and that these effects do not result indirectly via the generation of animal physical inactivity.

Effects of selective serotonin reuptake inhibitors on bone health in adults: time for recommendations about screening, prevention and management?

Evidence regarding a functional serotonin (5-hydroxytryptamine) signaling system in bone has generated considerable recent interest. The specific biochemical nature of serotoninergic pathways and their direct and/or indirect effects on bone metabolism are still unclear. Clinical evidence supports an effect of serotonin and altered serotonin signaling on bone metabolism. Serotonin is involved in the pathophysiology of depression, and therefore studies of depression and antidepressant treatments (as modulators of the serotonin system) are relevant with regard to bone outcomes. Studies on the effect of depression on bone mineral density (BMD) and fractures have been mixed. Studies on the associations between antidepressant use and BMD and/or fractures are more consistent. SSRIs have been associated with lower BMD and increased rates of bone loss, as well as increased rates of fracture after accounting for falls. These studies are limited by confounding because depression is potentially associated with both the outcome of interest (BMD and fracture) and the exposure (SSRIs). With mounting evidence for an effect on bone, this review considers the question of causality and whether selective serotonin reuptake inhibitors should be considered among those medications that contribute to bone loss, and therefore prompt clinicians to evaluate BMD proactively. Future research will be required to confirm the serotoninergic effects on bone and the biochemical pathways involved, and to identify clinical implications for treatment based on this novel pathway.

Male osteoporosis: new insights in an understudied disease.

PURPOSE OF REVIEW: Osteoporosis in men is increasingly recognized as an important health problem. New research contributes to our knowledge of gender differences in osteoporosis risk, diagnosis and management. We undertook this review to summarize recent developments in the field of male osteoporosis. RECENT FINDINGS: The paper reviews recently published studies that reveal new insights into male osteoporosis. It addresses epidemiology, risk factors, use of clinical risk assessment tools, diagnosis and treatment. New data continue to suggest that men have higher mortality rates than women after hip fracture, and that men may experience fractures at higher bone mineral density values than women. Treatments for osteoporosis have been studied mostly in women, but trials including both men and women are now being conducted. Likewise, there are several newer cohorts with bone and fracture outcomes that include men and women. The Osteoporotic Fractures in Men (MrOS) study is the first United States-based cohort to include only men; this study is contributing importantly to our understanding of epidemiology and risk factors for osteoporosis in men. SUMMARY: Men and their physicians should be aware of the risk for osteoporosis and the gender differences that exist within this disease. Further research is needed to continue to understand differences in pathophysiology, epidemiology and risk factors, and to promote appropriate therapies among men.

Association of low bone mineral density with selective serotonin reuptake inhibitor use by older men.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) are a widely used class of antidepressants that block the serotonin transporter. Osteoblasts and osteocytes express functional serotonin transporters; serotonin transporter gene disruption in mice results in osteopenia; and SSRI use has been associated with increased risk of hip fracture. METHODS: To determine whether SSRI use is associated with lower bone mineral density (BMD) in older men and to compare the results for SSRIs with those of other antidepressants, we performed a cross-sectional analysis of data from 5995 men 65 years and older participating in the prospective cohort Osteoporotic Fractures in Men Study. Main outcome measures included medication use; BMD at the femoral neck, greater trochanter, and lumbar spine measured by dual-energy x-ray absorptiometry; and potential covariates. RESULTS: In adjusted analyses, mean BMD among SSRI users (n=160) was 3.9% lower at the total hip and 5.9% lower at the lumbar spine compared with BMD in men reporting no antidepressant use (n=5708 [P=.002 for total hip; P<.001 for lumbar spine]). There was no significant difference among users of trazodone hydrochloride (n=52) or tricyclic antidepressants (n=99) compared with nonusers. Adjusting for variables that could be associated with BMD and/or SSRI use did not significantly alter these results. The observed difference in BMD for SSRIs is similar to that seen with glucocorticoids. CONCLUSIONS: In this population of men, BMD was lower among those reporting current SSRI use, but not among users of other antidepressants. Further research is needed to confirm this finding in light of widespread SSRI use and potentially important clinical implications.