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Introduction: Mal de Debarquement Syndrome (MdDS) is a rare central vestibular disorder characterised by a constant sensation of motion (rocking, swaying, bobbing), which typically arises after motion experiences (e.g. sea, air, and road travel), though can be triggered by non-motion events. The current standard of care is non-specific medications and interventions that only result in mild-to-moderate improvements. The vestibular ocular reflex (VOR) rehabilitation protocol, a specialised form of rehabilitation, has shown promising results in reducing symptoms amongst people with MdDS. Accumulating evidence suggests that it may be possible to augment the effects of VOR rehabilitation via non-invasive brain stimulation protocols, such as theta burst stimulation (TBS)., Methods: The aim of this randomised controlled trial was to evaluate the effectiveness of intermittent TBS (iTBS) over the dorsolateral prefrontal cortex in enhancing the effectiveness of a subsequently delivered VOR rehabilitation protocol in people with MdDS. Participants were allocated randomly to receive either Sham (n = 10) or Active (n = 10) iTBS, followed by the VOR rehabilitation protocol. Subjective outcome measures (symptom ratings and mental health scores) were collected 1 week pre-treatment and for 16 weeks post-treatment. Posturography (objective outcome) was recorded each day of the treatment week., Results: Significant improvements in subjective and objective outcomes were reported across both treatment groups over time, but no between-group differences were observed., Discussion: These findings support the effectiveness of the VOR rehabilitation protocol in reducing MdDS symptoms. Further research into iTBS is required to elucidate whether the treatment has a role in the management of MdDS. TRN: ACTRN12619001519145 (Date registered: 04 November 2019)., (© 2024. The Author(s).)

Introduction: Mal de Debarquement Syndrome (MdDS) is a neurological condition typically characterized by a sensation of motion, that persists longer than a month following exposure to passive motion (e.g., cruise, flight, etc.). The most common form of MdDS is motion triggered (MT). However, recently it has been acknowledged that some patients develop typical MdDS symptoms without an apparent motion trigger. These cases are identified here as spontaneous or other onset (SO) MdDS. This study aimed to address similarities and differences between the MdDS subtypes. Diagnostic procedures were compared and extensive diagnostic guidelines were proposed. Second, potential triggers and associated psychological components of MdDS were revealed., Methods: This was a retrospective online survey study for MT and SO MdDS patients. Participants were required to respond to a set of comprehensive questions regarding epidemiological details, as well as the diagnostic procedures and onset triggers., Results: There were 370 patients who participated in the surveys. It is indicated that MdDS is often misdiagnosed; more so for the SO group. In addition to the apparent self-motion, both groups reported associated levels of stress, anxiety and depression., Discussion: It appears at present that both MdDS subtypes are still poorly recognised. This was the first attempt to evaluate the diagnostic differences between MdDS subtypes and to propose a set of comprehensive diagnostic guidelines for both MdDS subtypes. In addition, the current research addressed that associated symptoms such as stress, anxiety and depression should also be considered when treating patients. We hope this study will help the medical community to broaden their awareness and diagnostic knowledge of this condition.

Objectives: These experiments examined the effects of selective 5-HT 1A , 5-HT 2A and 5-HT 2C receptor ligands on responding for a conditioned reinforcer (CRf). Effects of these ligands were measured under basal conditions and following elevated dopamine (DA) activity produced by the DA reuptake inhibitor methylphenidate., Methods: Water-restricted rats learned to associate a conditioned stimulus (CS) with water in operant chambers. Subsequently, two response levers were made available; responding on one lever delivered the CS (now a CRf), while responding on the second lever had no consequences. The effects of agonist and antagonists of 5-HT 1A (8-hydroxy-2(di-n-propylamino)tetralin hydrobromide (8-OH-DPAT) and N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide (WAY100635)), 5-HT 2A (DOI and M100907) and 5-HT 2C (Ro60-0175 and SB242084) receptors on responding were examined alone, as well as in the presence of methylphenidate., Results: Responding for a CRf was reduced by the agonists 8-OH-DPAT, DOI and Ro60-0175. 8-OH-DPAT also reduced responding for water and seemed to impair responding in a non-specific fashion. None of the receptor antagonists affected responding. Methylphenidate dose-dependently enhanced responding for a CRf, and this was attenuated by DOI and Ro60-0175. Conversely, the 5-HT 2C receptor antagonist SB242084 potentiated the effect of methylphenidate., Conclusions: No evidence was found for a behaviourally selective effect of 5-HT 1A receptor ligands on responding for a CRf. Activation of 5-HT 2A receptors selectively inhibits responding for a CRf. 5-HT 2C receptor ligands exerted bidirectional modulation of responding for a CRf, especially when DA activity was increased. This indicates that 5-HT 2C receptor activity is an important modulator of DA-dependent reward-related behaviours.

Rationale: Environmental factors influence the etiology of many psychiatric disorders. Likewise, environmental factors can alter processes central to motivation. Therefore, motivational deficits present in many disorders may be influenced by early life environmental conditions., Objective: We examined whether housing animals in different environmental conditions influenced the ability of sensory stimuli to acquire incentive value and whether elevated monoamine activity altered responsing for these stimuli., Methods: Isolation-housed (IH), pair-housed (PH), and environmentally enriched (EE) male C57BL/6N mice were examined in tests of responding for a conditioned reinforcer (CRf) or an unconditioned sensory reinforcer (USRf). The CRf was previously paired with saccharin delivery through Pavlovian conditioning, while the USRf was not conditioned with a reward. Following baseline tests of responding for the CRf or USRf, the effects of elevated monoamine activity were examined., Results: At baseline, PH and EE mice responded similarly for the CRf or USRf. IH mice responded more for the CRf but exhibited slower acquisition of responding for the USRf. Administration of citalopram, a serotonin transporter blocker, or atomoxetine, a norepinephrine transporter blocker, decreased responding for the CRf and USRf in all groups. The dopamine transporter blocker GBR 12909 generally increased responding for the CRf and USRf, but further analysis revealed enhanced responding for both reinforcers only in EE mice., Conclusions: Baseline incentive motivation is strongly influenced by the social component of housing conditions. Furthermore, environmental enrichment increased the sensitivity to elevated dopamine activity, while acute elevations in serotonin and norepinephrine inhibit incentive motivation irrespective of housing condition.