Effect of Passive Whole-Body Heating on Central Conduction and Cortical Excitability in Multiple Sclerosis Patients and Healthy Controls.

Effect of passive whole-body heating on central conduction and cortical excitability in multiple sclerosis patients and healthy controls.

J Appl Physiol. 2013 Apr 18;
White AT, Vanhaitsma TA, Vener J, Davis SL

Heat stress is associated with increased fatigue perception and decrements in function for individuals with multiple sclerosis (MS). Similarly, healthy individuals experience decrements in exercise performance during hyperthermia. Alterations in central nervous system (CNS) function during hyperthermia include reduced voluntary activation of muscle and increased effort perception. The purpose of this investigation was to test the hypothesis that passive heat exposure in MS patients will produce increased subjective fatigue and impairments in physiologic measures of central conduction and cortical excitability compared to healthy individuals. Eleven healthy individuals and 11 MS patients completed a series of transcranial magnetic stimulation (TMS) studies to examine central conduction and cortical excitability under thermoneutral (TN) and heat-stressed (HS) conditions at rest and after a fatiguing thumb abduction task. Passive heat stress resulted in significantly greater fatigue perception and impairments in force production in MS patients. Central motor conduction time (CMCT) was significantly shorter during HS in controls; however, in MS patients normal increases in conduction velocity with increased temperature were not observed centrally. MS patients also exhibited decreased cortical excitability during HS, evidenced by significant increases in resting motor threshold, decreased MEP amplitude, and decreased recruitment curve slope. Both groups exhibited post-exercise depression of MEP amplitude, but the magnitude of these decrements was amplified in MS patients during HS. Taken together, these results suggest that CNS pathology in MS patients played a substantial role in reducing cortical excitability during HS. HubMed – depression


Longitudinal Change in Physical Activity and Its Correlates in Relapsing-Remitting Multiple Sclerosis.

Phys Ther. 2013 Apr 18;
Motl RW, McAuley E, Sandroff BM

BACKGROUND: Physical activity is beneficial for persons with multiple sclerosis (MS), but this population is largely inactive. There is minimal information on change in physical activity and its correlates for informing the development of behavioral interventions. OBJECTIVE: We examined change in physical activity and its symptomatic, social-cognitive, and ambulatory/disability correlates over a 2.5 year period of time in persons with relapsing-remitting MS (RRMS). METHODS: On 6 occasions each separated by six months, persons (N = 269) with RRMS completed assessments of symptoms, self-efficacy, walking impairment, disability, and physical activity. The participants further wore an accelerometer for 7days. RESULTS: There were significant linear changes in self-reported (p<.05) and objectively(p<.001) measured physical activity, self-efficacy(p<.05), walking impairment(p<.05), and disability(p<.001) over the 2.5 year period; there were not changes in fatigue(p=.70), depression(p=.80), and pain(p=.06). The changes in self-reported and objective physical activity were associated with change in self-efficacy (?=.49 & ?=.61, respectively), after controlling for other variables and confounders. CONCLUSION: Researchers should consider designing interventions that target self-efficacy for the promotion and maintenance of physical activity in this population. HubMed – depression


Challenges in the Treatment of Major Depressive Disorder With Psychotic Features.

Schizophr Bull. 2013 Apr 18;
Rothschild AJ

Psychotic depression is associated with significant morbidity and mortality but is underdiagnosed and undertreated. In recent years, there have been several studies that have increased our knowledge regarding the optimal treatment of patients with psychotic depression. The combination of an antidepressant and antipsychotic is significantly more effective than either antidepressant monotherapy or antipsychotic monotherapy for the acute treatment of psychotic depression. Most treatment guidelines recommend either the combination of an antidepressant with an antipsychotic or ECT for the treatment of an acute episode of unipolar psychotic depression. The optimal maintenance treatment after a person responds to either the antidepressant/antipsychotic combination or the ECT is unclear particularly as it pertains to length of time the patient needs to take the antipsychotic medication. Little is known regarding the optimal treatment of a patient with bipolar disorder who has an episode of psychotic depression or the clinical characteristics of responders to medication treatments vs ECT treatments. HubMed – depression


Pharmacokinetic Analysis of Two Different Doses of Duloxetine Following Oral Administration in Dogs.

Drug Res (Stuttg). 2013 Apr 18;
Baek IH, Lee BY, Kang W, Kwon KI

Duloxetine is a potent and balanced dual inhibitor of serotonin and norepinephrine reuptake that is being investigated for the treatment of depression and urinary incontinence. The purpose of this study was to investigate the pharmacokinetic properties of duloxetine in 20 beagle dogs following a single oral administration of a 30- or 60-mg enteric-coated pellet in a capsule (Cymbalta).Following the administration of 30 or 60 mg of Cymbalta to 20 beagle dogs, the plasma concentration of duloxetine was measured using LC-MS/MS. Pharmacokinetic parameters were analyzed using both noncompartmental and compartmental approaches.The values of C max and AUC increased in proportion to the dose of duloxetine. The one compartment model with first-order absorption and a lag time was used successfully for pharmacokinetic analysis of duloxetine following a single oral administration of Cymbalta 30 mg or 60 mg.The studies described here are the first to report the pharmacokinetics of oral duloxetine in dogs, and these findings provide important information for pharmaceutical formulation research of duloxetine using dogs. HubMed – depression