Tinnitus is the perception of a sound in absence of any external source. It is described by the perceiver as a ringing, hissing, buzzing, whistling or whooshing sound. Prevalence of subjective tinnitus is estimated to be 21% in the general adult population, increasing to 30% in adults over 50 years of age. Though the cause of subjective tinnitus is complex,  consensus is for the abnormal neural activity and/or connectivity in auditory and non-auditory pathways in the brain. A chronic state is reported to have troublesome, debilitating effects on sleep (insomnia), cognitive abilities (concentration, memory), communication/social interaction, and negative responses (anxiety, depression). A range of therapies have been developed — psychological (counseling, relaxation, tinnitus retraining, cognitive behavioural therapies), auditory enrichment (sound), drug, electrical and electromagnetic — but no reliable cure is available, resulting in disability from cognitive, emotional and behavioural consequences, affecting the quality of life.
Cognitive behavioural therapy facilitates identifying, addressing and modifying dysfunctional thoughts, behaviours, and emotions associated with tinnitus. So the authors reviewed the effect of this therapy on tinnitus-related quality of life, adverse effects, depression, anxiety, general quality of life and negatively biased interpretations of tinnitus.

For whom is the review important?
Persons having tinnitus, their family members, professionals working with tinnitus, researchers, policymakers, and agencies involved in the funding of treatment (e.g. insurance companies).

Review objectives and the findings
The aim of this Cochrane systematic review was to assess the effects and safety of cognitive behavioural therapy for tinnitus in adults. It included 28 studies (mostly from Europe) published before November 2019 with a total of 2,733 participants. These participants experienced chronic tinnitus (for at least 3 months) and were adults (mean age greater than 18 years). The included randomized trial studies compared cognitive behavioural therapy (hospital or online session for 3 to 22 weeks) with no-intervention/waiting list, audiological care, tinnitus-retraining, and other experimental controls (transcranial magnetic stimulation, electrical or electromagnetic stimulation therapy, bio- neuro-feedback).

Key Results
Comparing cognitive behavioural therapy with the no-treatment group, low-certainty evidence was observed for improvement in tinnitus-related quality of life (at the end of treatment). It may also slightly reduce depression (low-certainty evidence) and anxiety. There were a few or no adverse effects. Compared to audiological care, tinnitus-retraining therapy and other types of treatment, the cognitive behavioural therapy probably reduces the negative impact of tinnitus on quality of life (moderate to low evidence). For depression, anxiety and general quality of life, the evidence was less certain. Few adverse effects and no significant differences between these groups were observed.
There was no significant difference on the effects of cognitive behavioural therapy when mode of delivery (face-to-face and online) was taken into account. Similarly, there was no difference when cognitive behavioural therapy was delivered individually or in groups. Authors also stated that results apply to all people seeking help for tinnitus-related distress, regardless of whether or not they have hearing loss.

Authors’ conclusions in the review
Cognitive behavioural therapy may be effective in reducing the negative impact that tinnitus can have on quality of life. There is, however, an absence of evidence at 6 or 12 months follow-up. There is also some evidence that adverse effects may be rare in adults with tinnitus receiving cognitive behavioural therapy, but this could be further investigated. Cognitive behavioural therapy for tinnitus may have small additional benefit in reducing symptoms of depression, though the quality of evidence is uncertain. Overall, there is limited evidence for cognitive behavioural therapy for tinnitus improving anxiety, health-related quality of life or negatively biased interpretations of tinnitus.

Future aspects of this review
It is a prerequisite to improve research design for implementing cognitive behavioural therapy as effective intervention for tinnitus. Predefined primary outcome measures (if one or multiple), magnitudes of effect sizes, information about adverse effects and methods of monitoring adverse effects associated with cognitive behavioural therapy should be reported. Authors recommended that future studies should consider the SPIRIT statement when designing study protocols, sample size calculation (with power analysis) and the CONSORT statement to report results. It is also necessary to study the long-term efficacy (effect persists 6 or 12 months) of cognitive behavioural therapy for tinnitus and the impact of 'booster' sessions in enhancing efficacy and/or delaying or preventing relapse from occurring.
 

Comment by Sunita Gudwani