Selective serotonin reuptake inhibitors: Their effect on high-intensity exercise performance

The body of evidence of late-life depression: the complex relationship between depressive symptoms, movement, dyspnea and cognition

BACKGROUND

Physical symptoms play an important role in late-life depression and may contribute to residual symptomatology after antidepressant treatment. In this exploratory study, we examined the role of specific bodily dimensions including movement, respiratory functions, fear of falling, cognition, and physical weakness in older people with depression.

METHODS

Clinically stable older patients with major depression within a Psychiatric Consultation-Liaison program for Primary Care underwent comprehensive assessment of depressive symptoms, instrumental movement analysis, dyspnea, weakness, activity limitations, cognitive function, and fear of falling. Network analysis was performed to explore the unique adjusted associations between clinical dimensions.

RESULTS

Sadness was associated with worse turning and walking ability and movement transitions from walking to sitting, as well as with worse general cognitive abilities. Sadness was also connected with dyspnea, while neurovegetative depressive burden was connected with activity limitations.

DISCUSSION

Limitations of motor and cognitive function, dyspnea, and weakness may contribute to the persistence of residual symptoms of late-life depression.

Anxiety Disorders in Athletes

Athletes and non-athletes experience many anxiety-related symptoms and disorders at comparable rates. Contributory factors may include pressure to perform, public scrutiny, sporting career dissatisfaction, injury, and harassment and abuse in sport. Anxiety may negatively impact sport performance. Specific types of anxiety may have unique presentations in athletes. It is important to rule out general medical and substance-related causes of anxiety symptoms. Psychotherapy and pharmacology treatment options should be considered, bearing in mind athletes' environmental circumstances and physiologies.

Cardiorespiratory fitness and incident use of anxiolytics and antidepressants in adults. A linkage study between HUNT and the Norwegian Prescription Database

BACKGROUND

We investigated the association between cardiorespiratory fitness (CRF) and incident use of antidepressants or anxiolytics in the general adult population.

METHODS

A non-exercise prediction model was used to estimate CRF in 32,603 participants in the third wave of the Trøndelag Health Study (HUNT3; 2006-08). Data on first purchase of antidepressants and anxiolytics were obtained from the Norwegian Prescription Database. Cox regression was used to estimate hazard ratios (HRs).

RESULTS

Each 1- metabolic equivalent of task (MET) increase in CRF was associated with 4 % reduced risk of purchasing antidepressant or anxiolytic medication during follow-up (HR 0.96, 95 % Confidence interval [CI] 0.94-0.98). Compared to the low CRF tertile, participants in intermediate (HR 0.93, 95 % CI 0.87-0.98) and high (HR 0.92, 95 % CI 0.86-0.98) CRF tertiles had reduced risk of medication purchase. Men in intermediate and high CRF tertile had lower risk of medication purchase (intermediate HR 0.87, 95 % CI 0.79-0.96; high HR 0.87, 95 % CI 0.78-0.96). Intermediate and high CRF tertiles were associated with reduced risk of medication use for younger adults (20 to <30 years old; intermediate HR 0.74, 95 % CI 0.61-0.91, high HR 0.78, 95 % CI 0.64-0.95) and middle-aged adults (30 to <65 years old; intermediate HR 0.90, 95 % CI 0.83-0.97, high HR 0.90, 95 % CI 0.84-0.98), but not in older adults (≥65 years old).

LIMITATIONS

Only information about medication purchase and not actual use was available.

CONCLUSION

Increased CRF is associated with reduced risk of anxiolytics and antidepressants purchase, with stronger effects for men and younger adults.

An exploration of the antecedents and mechanisms causing athletes' stress and twisties symptom

Research background

Twisties symptoms have attracted the world's attention in the sports field since the 2020 Tokyo Olympics.

Aim

However, studies on the symptoms and causes, inducing mechanisms, and relationships between DP/DR (Depersonalization/Derealization Disorder) and anxiety and depression for athletes have been sparse for both the general population and athletes. The literature on the twisties issue of athletes is quite scarce in the past.

Research method

Adopting the criteria appealing to PRISMA Items to review the subject twisties in a broader mode and combing with the IPO (Input-Process-Output) model for triangulation testing purpose, this study categorized the literature to explore input variables causing athletes’ twisties and identified process variables in psychological mechanisms bridging suppression and finally discussed the existing possible ways in helping athletes to solve problems caused by twisties.

Results

The authors formed 6 propositions in summarizing twisties' influential factors and mechanisms and tried to propose solutions to reduce the stress and the relevant twisties symptom of athletes. (1) Promotion of Athletes' Mental Toughness to Resist Stressors. (2) Interventions that correct for cognitive misinterpretations and appropriate relaxation and mindfulness practice in correcting a range of attention might reduce DP/DR. (3) Monitoring the athlete's HRV test results to ensure the Athlete's ability to resist pressure. (4) Avoid organizational stressors. (5) Written Emotional Disclosure method. (6) Improve various support systems for athletes: dual career paths. (7) Athletes' Stressful Awareness about the impact of gender, seniority, and environment.

Conclusion

Through the theoretical dialogue on the symptom of twisties, this study helps promote the development of the research of “twisties” and depersonalization-derealization symptoms (DDS); both have been under-researched.

Psychiatric medication and physical performance parameters - Are there implications for treatment?

INTRODUCTION

The impact of psychiatric medications and their enhancing or impairing effects on physical performance remains inconclusive. Therefore, with this systematic review we provide a comprehensive overview of frequently used psychotropic drugs and their effects on physical performance for the purpose of providing empirical information and deriving prescription and therapy recommendations for clinical practice.

METHODS

We systematically searched PubMed, PsycInfo, and Cochrane databases and extracted human studies investigating the effect of psychotropic drugs on parameters associated with the level of physical performance, such as exercise time, oxygen consumption, heart rate, muscle contraction or blood lactate concentration in physically healthy participants. 36 studies - comprising a broad range of psychotropic agents, such as antidepressants, antipsychotics, sedatives, and stimulants - were selected for final analyses.

RESULTS

Most studies (N = 32) were randomized controlled trials (RCT) with a double-blind crossover design. Antidepressants (N = 21) were the most frequently studied drug class, with contradictory results e.g., performance enhancement in warm environment but not in temperate conditions for bupropion or inconsistent findings between studies for other antidepressants. Antipsychotics (N = 3) mainly showed impairing effects on physical performance, while stimulants (N = 4) were often performance-enhancing. Sedatives (N = 9) may cause a hangover effect.

CONCLUSION

The examined studies with heterogeneous design showed different effects of psychiatric medications on physical performance. Antipsychotics seemed to be performance impairing, while the findings for antidepressants and sedatives were more inconsistent. Stimulants were the only group with consistent performance-enhancing effects. However, most studies were conducted with a small sample size (N < 10), mostly in well-trained subjects rather than in patients with psychiatric disorders, and most studies used single-dose designs. These issues impede the formulation of generalized conclusions for treatment regimes and should therefore be considered in further longitudinal studies for clinically reliable statements. Nevertheless, answering our research question is quite relevant for clinical practice and therapeutic prescription and should be further investigated especially considering the high drop-out rates in drug treatment.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=276103], identifier [CRD42021276103].

The Mental Health of Athletes: Recreational to Elite

ABSTRACT

Athletes at all levels of competition are susceptible to mental health symptoms and disorders, and this has been a topic of increased research attention in recent years. The most common such conditions will be highlighted in this article, with a clinical focus on unique aspects of presentation, diagnosis, and management among athletes. Conditions addressed include depression, anxiety and related disorders, eating disorders, sleep concerns, attention-deficit/hyperactivity disorder, bipolar and psychotic disorders, and substance use disorders and behavioral addictions. Athletes experience particular physiologic and psychosocial demands that impact how they present symptomatically and how treatment modalities, including psychotherapy and pharmacologic treatments, impact them.

Potential Role of Neuroactive Tryptophan Metabolites in Central Fatigue: Establishment of the Fatigue Circuit

Central fatigue leads to reduced ability to perform mental tasks, disrupted social life, and impaired brain functions from childhood to old age. Regarding the neurochemical mechanism, neuroactive tryptophan metabolites are thought to play key roles in central fatigue. Previous studies have supported the “tryptophan-serotonin enhancement hypothesis” in which tryptophan uptake into extensive brain regions enhances serotonin production in the rat model of exercise-induced fatigue. However, serotonin was transiently released after 30 minutes of treadmill running to exhaustion, but this did not reflect the duration of fatigue. In addition, as the vast majority of tryptophan is metabolized along the kynurenine pathway, possible involvement of the tryptophan-kynurenine pathway in the mechanism of central fatigue induction has been pointed out. More recently, our study demonstrated that uptake of tryptophan and kynurenine derived from the peripheral circulation into the brain enhances kynurenic acid production in rat brain in sleep deprivation–induced central fatigue, but without change in serotonin activity. In particular, dynamic change in glial-neuronal interactive processes within the hypothalamus-hippocampal circuit causes central fatigue. Furthermore, increased tryptophan-kynurenine pathway activity in this circuit causes reduced memory function. This indicates a major potential role for the endogenous tryptophan-kynurenine pathway in central fatigue, which supports the “tryptophan-kynurenine enhancement hypothesis.” Here, we review research on the basic neuronal mechanism underlying central fatigue induced by neuroactive tryptophan metabolites. Notably, these basic findings could contribute to our understanding of latent mental problems associated with central fatigue.

Distributed stimulation increases force elicited with functional electrical stimulation

OBJECTIVE

The maximum muscle forces that can be evoked using functional electrical stimulation (FES) are relatively modest. The reason for this weakness is not fully understood but could be partly related to the widespread distribution of motor nerve branches within muscle. As such, a single stimulating electrode (as is conventionally used) may be incapable of activating the entire array of motor axons supplying a muscle. Therefore, the objective of this study was to determine whether stimulating a muscle with more than one source of current could boost force above that achievable with a single source.

APPROACH

We compared the maximum isometric forces that could be evoked in the anterior deltoid of anesthetized monkeys using one or two intramuscular electrodes. We also evaluated whether temporally interleaved stimulation between two electrodes might reduce fatigue during prolonged activity compared to synchronized stimulation through two electrodes.

MAIN RESULTS

We found that dual electrode stimulation consistently produced greater force (~50% greater on average) than maximal stimulation with single electrodes. No differences, however, were found in the fatigue responses using interleaved versus synchronized stimulation.

SIGNIFICANCE

It seems reasonable to consider using multi-electrode stimulation to augment the force-generating capacity of muscles and thereby increase the utility of FES systems.

Mental health in elite athletes: International Olympic Committee consensus statement (2019)

Mental health symptoms and disorders are common among elite athletes, may have sport related manifestations within this population and impair performance. Mental health cannot be separated from physical health, as evidenced by mental health symptoms and disorders increasing the risk of physical injury and delaying subsequent recovery. There are no evidence or consensus based guidelines for diagnosis and management of mental health symptoms and disorders in elite athletes. Diagnosis must differentiate character traits particular to elite athletes from psychosocial maladaptations.

Management strategies should address all contributors to mental health symptoms and consider biopsychosocial factors relevant to athletes to maximise benefit and minimise harm. Management must involve both treatment of affected individual athletes and optimising environments in which all elite athletes train and compete. To advance a more standardised, evidence based approach to mental health symptoms and disorders in elite athletes, an International Olympic Committee Consensus Work Group critically evaluated the current state of science and provided recommendations.

Effect of quantity and quality of pre-exercise carbohydrate meals on central fatigue

Both the quantity and quality of pre-exercise carbohydrate (CHO) meals have been shown to improve endurance performance. However, their role in attenuating central fatigue (CF) is inconclusive. The use of neurophysiological techniques, such as voluntary activation (VA) and the central activation ratio (CAR), alongside maximum voluntary contraction (MVC) and sustained MVC (sMVC) can provide information on CF. Hence, the objective of this study was to investigate the effects of isocaloric pre-exercise meals: 1) a high versus low quantity of CHO and 2) a high quantity of CHO with a high versus low glycemic index (GI) on MVC, VA, and CAR following a 90-min run. The high and low quantity of CHO was 1.5 and 0.8 g/kg body wt, respectively, and high and low GI was ~75 and ~40, respectively. Blood insulin, serotonin, tryptophan, and gaseous exchange were also measured. High CHO preserved sMVC, VA, CAR, and serotonin postrunning with greater CHO oxidation and insulin response, whereas in low CHO, greater reductions in sMVC, VA, and CAR were accompanied by higher serotonin and fat oxidation with lower insulin response. These observations indicate central involvements. Meanwhile, high GI CHO better preserved force (sMVC), CAR, and tryptophan with greater CHO oxidation and insulin response compared with low GI. The findings of this study suggest that pre-exercise meals with varying quantity and quality of CHO can have an effect on CF, where greater CHO oxidation and insulin response found in both high CHO and high GI lead to attenuation of CF. NEW & NOTEWORTHY This paper examined the effects of carbohydrate interventions (high and low: quantity and quality wise) on central activity during prolonged exercise using mainly neurophysiological techniques along with gaseous exchange and blood insulin, serotonin, and tryptophan data.

The sports psychiatrist and psychiatric medication

There are several critical factors to consider in prescribing psychiatric medications to athletes. In addition to the usual considerations when prescribing any psychotropic agent to any patient, the prescriber in this case should pay careful attention to: (1) potential negative impact of the medication on athletic performance, (2) potential performance-enhancing effects, and (3) potential safety risks. This paper describes an updated review of relevant research findings and considerations in the above areas within various categories of psychiatric medications. Many methodological concerns exist with the studies that have examined psychotropic medication use by athletes. These include: small sample sizes; use of the medication in dosing strategies (e.g. single dose) that do not replicate how they are usually taken in the real world; use of primarily male subjects only; use of performance measures (e.g. subtraction, multitask) in some studies that may not align with physical demands experienced by athletes in their natural athletic environments; and not using athletes who actually have the psychiatric disorder or symptom the medication was designed to treat. Despite these concerns, data currently available provide at least some guidance for clinicians wishing to make informed decisions about psychotropic prescribing for their athlete-patients.

Psychiatric medication preferences of sports psychiatrists

OBJECTIVES

When prescribing psychiatric medications to athletes, it is important to consider issues that are especially important for this population, including side effects, safety concerns, and anti-doping policies. Only one report, from 2000, describes the prescribing preferences of psychiatrists who work with athletes. This manuscript aims to update the findings from that report, so as to help inform prescribing practices of primary care physicians, psychiatrists, and other clinicians who work with athletes.

METHODS

Physician members of the International Society for Sports Psychiatry (ISSP) were sent an email invitation in 2016 to complete an anonymous web-based survey on psychiatric medication prescribing preferences in working with athletes with a variety of mental health conditions.

RESULTS

Forty of 100 (40%) members of the ISSP who identified as physicians and who were emailed the survey ultimately completed it. Top choices of psychiatric medications for athletes across categories assessed included: bupropion for depression without anxiety and without bipolar spectrum disorder; escitalopram for generalized anxiety disorder; melatonin for insomnia; atomoxetine for attention-deficit/hyperactivity disorder; lamotrigine for bipolar spectrum disorders; and aripiprazole for psychotic disorders.

CONCLUSION

Prescribers of psychiatric medications for athletes tended to favor medications that are relatively more energizing and less likely to cause sedation, weight gain, cardiac side effects, and tremor. Additionally, prescribing preferences for athletes diverged from many of the prescribing trends seen for patients within the general population, in keeping with the assumption that different factors are considered when prescribing for athletes versus for the general population.

Muscle fatigability and control of force in men with posttraumatic stress disorder

INTRODUCTION

Acute stress can increase fatigability and decrease steadiness of sustained low-force contractions that are required for functional tasks in upper limb muscles. Whether motor performance is more impaired in people with a chronic stress disorder is not known.

PURPOSE

This study compared the fatigability and steadiness (force fluctuations) of handgrip muscles in veterans with posttraumatic stress disorder (PTSD) and civilian controls in the presence and absence of varying levels of cognitive demand.

METHODS

Eighteen veterans with PTSD and 21 healthy controls (33 ± 9 yr) attended three randomized experimental sessions to perform an isometric fatiguing contraction (20% of maximal strength) with the handgrip muscles. Two sessions involved performing a cognitive task during the fatiguing contraction: 1) difficult mental math task (stressor) and 2) a simple mental math task (mental attentiveness). A third session involved a fatiguing contraction with no mental task (control).

RESULTS

Stress elevated heart rate, blood pressure, and levels of anxiety in veterans with PTSD (P < 0.05) but blunted cortisol levels (P < 0.05). Time to failure was briefer (7.2 ± 2.5 vs 9.3 ± 5.2 min, P = 0.03), and force fluctuations increased at a greater rate for veterans with PTSD than for controls (P < 0.05). Cognitive stress did not influence time to failure or force fluctuations for either group (P > 0.05).

CONCLUSIONS

Veterans with PTSD demonstrated greater fatigability and loss of steadiness (greater force fluctuations) of the handgrip muscles compared with healthy controls.

SIGNIFICANCE

Male veterans with PTSD demonstrated altered neuromuscular function of arm muscles that potentially affects functional tasks during daily, ergonomic, and military activities.

The effects of venlafaxine on cortical motor area activity in healthy subjects: a pilot study

In the study, we used functional magnetic resonance imaging associated with behavioral assessment to observe the effects of venlafaxine on the modulation of human motor cortex activation and to provide preliminary data for further assessing its influence on motor functional reorganization after stroke injury. In a randomized, double-blind, crossover study, 8 right-handed subjects received 75 mg of either venlafaxine or a placebo daily over a period of 7 days separated by 3 washout days. The volunteers were asked to execute motor tasks, which included the dynamometer and finger-tapping test. In addition, laboratory tests and functional magnetic resonance imaging examination, before the start of the experiment and after administration of placebo and venlafaxine, were performed. It was shown that the finger-tapping rate of each hand in the venlafaxine stage was significantly improved compared with that observed in the placebo stage (n = 8, F left hand = 57.69, F right hand = 184.48, P < 0.001). The changes in the recorded grip strengths of both hands were not significant between the stages (n = 8, F = 2.63, P > 0.05). In the venlafaxine stage, the activations of the contralateral primary sensorimotor cortex, contralateral premotor cortex, and contralateral supplementary motor area were enhanced significantly, whereas the activation of the bilateral parietal cortices was decreased when compared with the placebo stage. Meanwhile, the enhancement of contralateral primary sensorimotor cortex activation had a positive correlation with the improvement of the finger-tapping rate. It was concluded that venlafaxine could modulate the cortical excitability and improve finger dexterity and reaction speed, which greatly related to the increase of contralateral motor cortical excitability.

Fluoxetine prevents acetylcholine-induced excitotoxicity blocking human endplate acetylcholine receptor

INTRODUCTION

Fluoxetine is an open channel blocker of fetal muscle acetylcholine (ACh) receptor (AChR) and slow-channel mutant AChRs. It is used commonly to treat patients with slow-channel congenital myasthenic syndromes. Fluoxetine effects on adult wild-type endplate AChR are less characterized, although muscle AChR isoforms are differentially modulated by some drugs.

METHODS

Excitotoxicity assays and patch clamp recordings were performed in human embryonic kidney 293 (HEK) cells expressing wild-type or slow-channel mutant human AChRs.

RESULTS

Fluoxetine (2-10 μM) abolished ACh-induced death and decreased ACh-activated whole-cell currents in cells expressing all AChR types. In outside-out patches, fluoxetine rapidly curtailed ACh evoked unitary activity and macroscopic currents. The effect was increased if fluoxetine was applied before ACh.

CONCLUSIONS

Fluoxetine is an open channel blocker, but it also affects AChR in the closed state. AChR blockade likely underlies the rescue of HEK cells from ACh-induced death.

Psychiatric and neuropsychological issues in sports medicine

This article reviews psychiatric/psychological issues in the athletic training room, including recognition of these issues and a framework for management. Because the majority of research has been conducted in college settings, most of the issues discussed are presented in the context of college sports, although the results generalize to other athletic arenas. Greater awareness of psychological issues, empirical research, and education about mental health issues in the sports medicine community are clearly needed.

Sport psychiatry: a systematic review of diagnosis and medical treatment of mental illness in athletes

Sport psychiatry focuses on diagnosis and treatment of psychiatric illness in athletes in addition to utilization of psychological approaches to enhance performance. As this field and its research base are relatively new, clinicians often deliver psychiatric care to athletes without a full understanding of the diagnostic and therapeutic issues unique to this population. In this systematic review, we discuss published findings relating to psychiatric diagnosis and medical treatment of mental illness in athletes. There have been several studies looking at the prevalence of some psychiatric disorders in various athlete populations. Eating disorders and substance abuse are the most studied of these disorders and appear to be common problems in athletes. However, to provide informed understanding and treatment, we especially need more research on overtraining syndrome, bipolar disorder, suicidality, anxiety disorders, attention-deficit hyperactivity disorder (ADHD) and psychosis in athletes. Research is needed in the areas of prevalence, risk factors, prognosis and the unique experiences facing athletes with any of these disorders. Additionally, there have not been any large, systematic studies on the use of psychotropic medications in athletes. Small studies suggest that some medications may either be performance enhancing or detrimental to performance, but we need larger studies with rigorous methodology. Higher level athletes suffering from psychiatric symptoms often have reservations about taking medications with unknown performance and safety effects, and methodological issues with the current literature database preclude any definitive conclusions on performance effects of psychiatric medications. We need many more, higher quality studies on the use by athletes of antidepressants, mood stabilizers, anxiolytics, stimulants and other ADHD medications, sedative-hypnotics and antipsychotics. Such studies should utilize sensitive performance measures and involve longer term use of psychotropic medications. Furthermore, study subjects should include athletes who actually have the psychiatric disorder for which the medication is proposed, and should include more women.

Alterations in central fatigue by pharmacological manipulations of neurotransmitters in normal and high ambient temperature

The scientific evidence is reviewed for the involvement of the brain monoamines serotonin, dopamine and noradrenaline (norepinephrine) in the onset of fatigue, in both normal and high ambient temperatures. The main focus is the pharmacological manipulations used to explore the central fatigue hypothesis. The original central fatigue hypothesis emphasizes that an exercise-induced increase in serotonin is responsible for the development of fatigue. However, several pharmacological studies attempted and failed to alter exercise capacity through changes in serotonergic neurotransmission in humans, indicating that the role of serotonin is often overrated. Recent studies, investigating the inhibition of the reuptake of both dopamine and noradrenaline, were capable of detecting changes in performance, specifically when ambient temperature was high. Dopamine and noradrenaline are prominent in innervated areas of the hypothalamus, therefore changes in the catecholaminergic concentrations may also be expected to be involved with the regulation of body core temperature during exercise in the heat. Evidence from different studies suggests that it is very unlikely that one neurotransmitter system is responsible for the appearance of central fatigue. The exact mechanism of fatigue is not known; presumably a complex interplay between both peripheral and central factors induces fatigue. Central fatigue will be determined by the collaboration of the different neurotransmitter systems, with the most important role possibly being for the catecholamines dopamine and noradrenaline.

The effect of selective serotonin reuptake inhibitors in healthy subjects. A systematic review

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) show antidepressant properties in many patients with a diagnosis of depression. An understanding of the underlying mechanisms of the effect of SSRIs in healthy patients may lead to an understanding of the yet unclear pathophysiology of depression. Recent reviews of studies investigating the effect of SSRIs in healthy persons conclude that the results are inconsistent and that--in relation to a wide range of outcomes--the effect of SSRIs is limited; however, reasons for the inconsistencies are poorly studied.

AIMS AND METHODS

To investigate whether methodological artefacts can explain the diverging findings, we conducted a systematic review of all randomized multiple-dose, placebo-controlled trials on the effect of treatment by SSRI for at least a week in healthy persons published before January 2009.

RESULTS

We identified 33 trials, investigating six SSRIs and 163 outcome tests. The effect of SSRI showed divergence presumably related to methodological issues. Specifically, it is likely that the majority of studies included a mix of healthy persons with and without a family history of affective disorders. Few presented information on factors that may influence outcomes such as age, gender, family history of psychiatric disorder, drug levels and ethnicity. No study fulfilled principles of conducting and reporting randomized controlled trials, according to the CONSORT Statement guidelines.

CONCLUSIONS

It is unclear whether the effect of SSRIs in healthy persons may lead to an understanding of the pathophysiology of depression, since the present evidence is divergent and may be severely influenced by a number of methodological drawbacks.

Central fatigue: the serotonin hypothesis and beyond

The original central fatigue hypothesis suggested that an exercise-induced increase in extracellular serotonin concentrations in several brain regions contributed to the development of fatigue during prolonged exercise. Serotonin has been linked to fatigue because of its well known effects on sleep, lethargy and drowsiness and loss of motivation. Several nutritional and pharmacological studies have attempted to manipulate central serotonergic activity during exercise, but this work has yet to provide robust evidence for a significant role of serotonin in the fatigue process. However, it is important to note that brain function is not determined by a single neurotransmitter system and the interaction between brain serotonin and dopamine during prolonged exercise has also been explored as having a regulative role in the development of fatigue. This revised central fatigue hypothesis suggests that an increase in central ratio of serotonin to dopamine is associated with feelings of tiredness and lethargy, accelerating the onset of fatigue, whereas a low ratio favours improved performance through the maintenance of motivation and arousal. Convincing evidence for a role of dopamine in the development of fatigue comes from work investigating the physiological responses to amphetamine use, but other strategies to manipulate central catecholamines have yet to influence exercise capacity during exercise in temperate conditions. Recent findings have, however, provided support for a significant role of dopamine and noradrenaline (norepinephrine) in performance during exercise in the heat. As serotonergic and catecholaminergic projections innervate areas of the hypothalamus, the thermoregulatory centre, a change in the activity of these neurons may be expected to contribute to the control of body temperature whilst at rest and during exercise. Fatigue during prolonged exercise clearly is influenced by a complex interaction between peripheral and central factors.

The brain and fatigue: new opportunities for nutritional interventions?

It is clear that the cause of fatigue is complex, influenced by events occurring in both the periphery and the central nervous system. Work conducted over the last 20 years has focused on the role of brain serotonin and catecholamines in the development of fatigue, and the possibility that manipulation of neurotransmitter precursors may delay the onset of fatigue. While there is some evidence that branched-chain amino acid and tyrosine ingestion can influence perceived exertion and some measures of mental performance, the results of several apparently well-controlled laboratory studies have not demonstrated a positive effect on exercise capacity or performance under temperate conditions. As football is highly reliant upon the successful execution of motor skills and tactics, the possibility that amino acid ingestion may help to attenuate a loss in cognitive function during the later stages of a game would be desirable, even in the absence of no apparent benefit to physical performance. There are several reports of enhanced performance of high-intensity intermittent exercise with carbohydrate ingestion, but at present it is difficult to separate the peripheral effects from any potential impact on the central nervous system. The possibility that changes in central neurotransmission play a role in the aetiology of fatigue when exercise is performed in high ambient temperatures has recently been examined, although the significance of this in relation to the pattern of activity associated with football has yet to be determined.

Comparison of the effects of two antidepressants on exercise performance of the female patients with fibromyalgia

OBJECTIVE

To compare the effects of two antidepressants on exercise performance of the female patients with fibromyalgia.

METHODS

Fifteen patients with fibromyalgia participated in this randomized, double-blind crossover study composed of two trials separated by a 2-week washout phase. The pharmacy randomly assigned patients to two groups: (a) placebo (glucose) in the morning and 25 mg amitriptyline at bedtime or (b) 20 mg fluoxetine in the morning and placebo at bedtime. The VO(2max) and Wingate anaerobic test were evaluated. Within 24 h after 15-day medication, the tests were repeated.

RESULTS

Peak power and fatigue index increased, and VO(2max) and VT did not change with both fluoxetine and amitriptyline. Mean power significantly increased after fluoxetine but not after amitriptyline.

CONCLUSION

Both amitriptyline administration and fluoxetine administration in patients with fibromyalgia have beneficial effects on anaerobic performance. These effects may be important in life quality of the female patients with fibromyalgia.

Modulation of behavior and cortical motor activity in healthy subjects by a chronic administration of a serotonin enhancer

SSRIs are postulated to modulate motor behavior. A single dose of selective serotoninergic reuptake inhibitors (SSRIs) like fluoxetine, paroxetine, or fluvoxamine, has been shown to improve motor performance and efficiency of information processing for simple sensorimotor tasks in healthy subjects. At a cortical level, a single dose of SSRI was shown to induce a hyperactivation of the primary sensorimotor cortex (S1M1) involved in the movement (Loubinoux, I., Boulanouar, K., Ranjeva, J. P., Carel, C., Berry, I., Rascol, O., Celsis, P., and Chollet, F., 1999. Cerebral functional magnetic resonance imaging activation modulated by a single dose of the monoamine neurotransmission enhancers fluoxetine and fenozolone during hand sensorimotor tasks. J. Cereb. Blood Flow Metab. 19 1365--1375, Loubinoux, I., Pariente, J., Boulanouar, K., Carel, C., Manelfe, C., Rascol, O., Celsis, P., and Chollet, F., 2002. A Single Dose of Serotonin Neurotransmission Agonist Paroxetine Enhances Motor Output. A double-blind, placebo-controlled, fMRI study in healthy subjects. NeuroImage 15 26--36). Since SSRIs are usually given for several weeks, we assessed the behavioral and cerebral effects of a one-month chronic administration of paroxetine on a larger group. In a double-blind, placebo controlled and crossover study, 19 subjects received daily 20 mg paroxetine or placebo, respectively, over a period of 30 days separated by a wash-out period of 3 months. After each period, the subjects underwent an fMRI (active or passive movement, dexterity task, sensory discrimination task) and a behavioral evaluation. Concurrently, a TMS (transcranial magnetic stimulation) study was conducted (Gerdelat-Mas, A., Loubinoux, I., Tombari, D., Rascol, O., Chollet, F., Simonetta-Moreau, M., 2005. Chronic administration of selective serotonin re-uptake inhibitor (SSRI) paroxetine modulates human motor cortex excitability in healthy subjects. NeuroImage 27,314--322).

RESULTS

On the one hand, paroxetine improved motor performances at the finger tapping test (P=0.02) without affecting choice reaction time, strength and dexterity significantly. Subjects were also faster in processing the spatial incongruency between a stimulus and the motor response (P=0.04). In order to differentiate behavioral components, a principal component analysis was performed on all motor tests, and several characteristics were differentiated: strength, speed, skill, attention, and motor response coding. Paroxetine would improve the efficiency of motor response coding (MANOVA on the factors; factor 3, P=0.01). On the other hand, the chronic administration induced a significant hypoactivation of S1M1 whatever the task: motor or sensory, simple or complex (random effect analysis, P<0.05). The hypoactivation correlated with the improvement of performances at the finger tapping test (P<0.05) suggesting more efficiency in cerebral motor processing.

CONCLUSIONS

Our results showed a clear modulation of sensory and motor cerebral activation after a chronic paroxetine administration. An improvement in both behavior and cerebral efficiency was suggested. It could be hypothesized that monoamines, by an unspecific effect, may tune the response of pyramidal neurons to optimize performances.

Biomarkers for the effects of selective serotonin reuptake inhibitors (SSRIs) in healthy subjects

AIMS

Studies of novel centrally acting drugs in healthy volunteers are traditionally concerned with kinetics and tolerability, but useful information may also be obtained from biomarkers of clinical endpoints. This paper provides a systematic overview of CNS-tests used with SSRIs in healthy subjects. A useful biomarker should meet the following requirements: a consistent response across studies and drugs; a clear response of the biomarker to a therapeutic dose; a dose-response relationship; a plausible relationship between biomarker, pharmacology and pathogenesis.

METHODS

These criteria were applied to all individual tests found in studies of selective serotonin reuptake inhibitors (SSRIs), performed in healthy subjects since 1966, identified with a systematic MedLine search. Separate databases were created to evaluate the effects of single or multiple dose SSRI-studies, and for amitriptyline whenever the original report included this antidepressant as a positive control. Doses of the antidepressant were divided into high- and low-dose ranges, relative to a medium range of therapeutic doses. For each test, the drug effects were scored as statistically significant impairment/decrease (-), improvement/increase (+) or no change (=) relative to placebo.

RESULTS

56 single dose studies and 22 multiple dose studies were identified, investigating the effects of 13 different SSRIs on 171 variants of neuropsychological tests, which could be clustered into seven neuropsychological domains. Low single doses of SSRIs generally stimulated tests of attention and memory. High doses tended to impair visual/auditory and visuomotor systems and subjective performance, while showing an acceleration in motor function. The most pronounced effects were observed using tests that measure flicker discrimination (improvement at low doses: 75%, medium doses: 40%, high doses: 43% of studies); REM sleep (inconsistent decrease after medium doses, decrease in 83% of studies after high doses); and EEG recordings, predominantly in alpha (decrease in 60% and 43% of studies after low and medium doses, respectively) and in theta activity (increase in 43% and 33% of studies after medium and high doses, respectively). Amitriptyline generally impaired central nervous system (CNS) functions, which increased with doses. Multiple doses caused less pronounced effects on the reported tests. The most responsive tests to amitriptyline appeared to be EEG alpha and theta, and REM sleep duration.

CONCLUSIONS

SSRIs in healthy subjects appear to cause slight stimulating effects after low doses, which tend to diminish with dose. The most consistent effects were observed with flicker discrimination tests, EEG (alpha and beta bands), REM sleep duration, and subjective effects at higher doses. These effects are small compared with amitriptyline and other CNS-active drugs. Multiple dosing with SSRIs caused even fewer measurable differences from placebo, probably due to adaptive processes. SSRI-effects are best detected with a test battery that is sensitive to general CNS-stimulation, but such tests only comprise a very small portion of the close to 200 different methods that were found in current review.

Psychiatric and Neuropsychological Issues in Sport Medicine

This article reviews what is known about training room psychiatric/psychological issues and how to recognize them, and provides an initial framework for how to manage them. There is some focus on psychiatric issues involved in collegiate sports medicine environments, because the majority of research on this topic has been done with this population, but it is believed that this information generalizes to other athletic settings. Greater awareness of these problems, empirical research, and education about mental health issues in the sports medicine community is clearly needed.

Selective serotonin reuptake inhibitor paroxetine modulates motor behavior through practice. A double-blind, placebo-controlled, multi-dose study in healthy subjects

We hypothesized that selective serotonin reuptake inhibitors (SSRIs) could modulate motor activity in healthy subjects in a dose-dependent manner. The effects of a single dose of paroxetine were tested in a double-blind, placebo-controlled study. Six randomized and counterbalanced subjects performed behavioral tests in three sessions 1 week apart (E1, E2 and E3) at peak plasma concentration (5 h after drug intake). Each subject was given 20 mg or 60 mg of the drug, or a placebo. Tasks were the Nine Peg Hole test (three trials), Moede dexteritymeter (two trials), and compatible and incompatible reaction time tasks. The results show that at the first trials, performance did not differ after placebo or paroxetine intake. However, 20 and 60 mg of paroxetine improved performance significantly at the third trial of the Nine Peg Hole test and subjects receiving the drug performed 7% faster than those under placebo. An amount of 20 mg, but not 60 mg, of paroxetine improved dexterity significantly at the second trial of the Moede test and subjects performed 30% faster. Conversely, the drug did not affect reaction time for the compatible task and subjects were 11% slower under 20 mg with the incompatible task. Thus, paroxetine decreased the ability to inhibit automatism. Thus, it was concluded that a single dose of paroxetine improved motor performance through practice. But negative effects occurred on tasks including the inhibition of an automatism. Paroxetine enhanced brain motor output (motor activity in S1M1) [NeuroImage, 15 (2002) 26]. This S1M1 hyperactivation is likely to be responsible for the better performance. The brain effect and motor improvement were dose dependent. For both, 20 mg was the optimal dose.