Efficacy of different protocols of transcranial magnetic stimulation for the treatment of tinnitus: Pooled analysis of two randomized controlled studies.

OBJECTIVES: Tinnitus is related to alterations in neuronal activity of auditory and nonauditory brain areas. Targeted modulation of these areas by repetitive transcranial magnetic stimulation (rTMS) has been proposed as a new therapeutic approach for chronic tinnitus. METHODS: Two randomized, double-blind, parallel-group, controlled clinical trials were performed subsequently and pooled for analysis. A total of 192 tinnitus patients were randomly allocated to receive 10 stimulation sessions of either sham rTMS, PET-based neuronavigated 1 Hz rTMS, 1Hz r TMS over the left auditory cortex, or combined 20 Hz rTMS over the left frontal cortex, followed by 1 Hz rTMS over the left auditory cortex. RESULTS: rTMS treatment was well tolerated and no severe side effects were observed. All active rTMS treatments resulted in significant reduction of the TQ as compared to baseline. The comparison between treatment groups failed to reach significant differences. The number of treatment responders was higher for temporal rTMS(38%) and combined frontal and temporal rTMS (43%), as compared to sham (6%). CONCLUSIONS: This large study demonstrates the safety and tolerability of rTMS treatment in patients with chronic tinnitus. While the overall effect did not prove superior to placebo, secondary outcome parameters argue in favour of the active stimulation groups, and specifically the combined frontal and temporal rTMS protocol.

Resequencing of the auxiliary GABA(B) receptor subunit gene KCTD12 in chronic tinnitus.

Tinnitus is a common and often incapacitating hearing disorder marked by the perception of phantom sounds. Susceptibility factors remain largely unknown but GABA(B) receptor signaling has long been implicated in the response to treatment and, putatively, in the etiology of the disorder. We hypothesized that variation in KCTD12, the gene encoding an auxiliary subunit of GABA(B) receptors, could help to predict the risk of developing tinnitus. Ninety-five Caucasian outpatients with a diagnosis of chronic tinnitus were systematically screened for mutations in the KCTD12 open reading frame and the adjacent 3' untranslated region by Sanger sequencing. Allele frequencies were determined for 14 known variants of which three (rs73237446, rs34544607, and rs41287030) were polymorphic. When allele frequencies were compared to data from a large reference population of European ancestry, rs34544607 was associated with tinnitus (p = 0.04). However, KCTD12 genotype did not predict tinnitus severity (p = 0.52) and the association with rs34544607 was weakened after screening 50 additional cases (p = 0.07). Pending replication in a larger cohort, KCTD12 may act as a risk modifier in chronic tinnitus. Issues that are yet to be addressed include the effects of neighboring variants, e.g., in the KCTD12 gene regulatory region, plus interactions with variants of GABA(B1) and GABA(B2).

An examination of TOR1A variants in recurrent major depression.

BACKGROUND: Observations of comorbid depression in subjects with primary dystonia have suggested a dual role for the TOR1A gene in mood disorders and movement disorders. We conducted a systematic search for carriers of the ΔGAG deletion and for other variants in TOR1A exon 5 among 414 Caucasian subjects with recurrent major depression from the Upper Palatinate. FINDINGS: Allele frequencies were determined for 27 TOR1A diallelic markers, including two novel synonymous substitutions (L262L and E310E) in the region encoding the torsinA C-terminus, plus four novel variants in the gene's 3'UTR. No carriers of the ΔGAG deletion were observed. When data were compared to previously examined control populations, no significant allelic associations were noted after corrections for multiple testing. CONCLUSIONS: The present study adds to the spectrum of TOR1A mutations but provides no evidence of a common genetic predisposition to DYT1 dystonia and recurrent major depression.

Tea catechins' affinity for human cannabinoid receptors.

Among the many known health benefits of tea catechins count anti-inflammatory and neuroprotective activities, as well as effects on the regulation of food intake. Here we address cannabimimetic bioactivity of catechin derivatives occurring in tea leaves as a possible cellular effector of these functionalities. Competitive radioligand binding assays using recombinant human cannabinoid receptors expressed in Chem-1 and CHO cells identified (-)-epigallocatechin-3-O-gallate, EGCG (K(i)=33.6 microM), (-)-epigallocatechin, EGC (K(i)=35.7 microM), and (-)-epicatechin-3-O-gallate, ECG (K(i)=47.3 microM) as ligands with moderate affinity for type 1 cannabinoid receptors, CB1. Binding to CB2 was weaker with inhibition constants exceeding 50 microM for EGC and ECG. The epimers (+)-catechin and (-)-epicatechin exhibited negligible affinities for both CB1 and CB2. It can be concluded that central nervous cannabinoid receptors may be targeted by selected tea catechins but signaling via peripheral type receptors is less likely to play a major role in vivo.

Berry anthocyanins and anthocyanidins exhibit distinct affinities for the efflux transporters BCRP and MDR1.

BACKGROUND AND PURPOSE: Dietary anthocyanins hold great promise in the prevention of chronic disease but factors affecting their bioavailability remain poorly defined. Specifically, the role played by transport mechanisms at the intestinal and blood-brain barriers (BBB) is currently unknown. EXPERIMENTAL APPROACH: In the present study, 16 anthocyanins and anthocyanidins were exposed to the human efflux transporters multidrug resistance protein 1 (MDR1) and breast cancer resistance protein (BCRP), using dye efflux, ATPase and, for BCRP, vesicular transport assays. KEY RESULTS: All test compounds interacted with the BCRP transporter in vitro. Of these, seven emerged as potential BCRP substrates (malvidin, petunidin, malvidin-3-galactoside, malvidin-3,5-diglucoside, cyanidin-3-galactoside, peonidin-3-glucoside, cyanidin-3-glucoside) and 12 as potential inhibitors of BCRP (cyanidin, peonidin, cyanidin-3,5-diglucoside, malvidin, pelargonidin, delphinidin, petunidin, delphinidin-3-glucoside, cyanidin-3-rutinoside, malvidin-3-glucoside, pelargonidin-3,5-diglucoside, malvidin-3-galactoside). Malvidin, malvidin-3-galactoside and petunidin exhibited bimodal activities serving as BCRP substrates at low concentrations and, at higher concentrations, as BCRP inhibitors. Effects on MDR1, in contrast, were weak. Only aglycones exerted mild inhibitory activity. CONCLUSIONS AND IMPLICATIONS: Although the anthocyanidins under study may alter pharmacokinetics of drugs that are BCRP substrates, they are less likely to interfere with activities of MDR1 substrates. The present data suggest that several anthocyanins and anthocyanidins may be actively transported out of intestinal tissues and endothelia, limiting their bioavailability in plasma and brain.

Genetics of chronic tinnitus.

Susceptibility to chronic tinnitus is highly variable and of particular interest when it comes to defining strategies for prevention and treatment. While several rare monogenic disorders have been described that are associated with tinnitus, the genetic underpinnings of the more common forms of the syndrome are still poorly understood. The present article incorporates recent advancements in the field, including the epidemiology of tinnitus in subjects with neuropsychiatric illness, and highlights pilot studies of candidate genes.

Tinnitus severity, depression, and the big five personality traits.

A growing number of self-report measures for the evaluation of tinnitus severity has become available to research and clinical practice. This has led to an increased awareness of depression and personality as predictors of tinnitus severity in addition to loudness and other psychoacoustic measures. However, the net impact of personality dimensions on tinnitus ratings has not been investigated when the effect of depressed mood is controlled. In the present study, we demonstrate the role of the big five personality traits, 'Neuroticism', 'Extraversion', 'Openness', 'Agreeableness', and 'Conscientiousness', in affecting scores on two standard instruments for grading tinnitus-related complaints, the tinnitus handicap inventory (THI), and the tinnitus questionnaire (TQ). When 72 individuals with chronic tinnitus were examined, 'Agreeableness' negatively correlated with THI scores (p=.003), whereas the anxiety trait 'Neuroticism' correlated both with depressive symptomatology (p<.001) and TQ scores (p=.028), but not with THI ratings (n.s.). In addition to confirming the established roles of trait anxiety and depression, low 'Agreeableness' was thus identified as a novel predictor of tinnitus severity on the THI.

Consensus for tinnitus patient assessment and treatment outcome measurement: Tinnitus Research Initiative meeting, Regensburg, July 2006.

There is widespread recognition that consistency between research centres in the ways that patients with tinnitus are assessed and outcomes following interventions are measured would facilitate more effective co-operation and more meaningful evaluations and comparisons of outcomes. At the first Tinnitus Research Initiative meeting held in Regensburg in July 2006 an attempt was made through workshops to gain a consensus both for patient assessments and for outcome measurements. It is hoped that this will contribute towards better cooperation between research centres in finding and evaluating treatments for tinnitus by allowing better comparability between studies.