Lower Glutamate and GABA Levels in Auditory Cortex of Tinnitus Patients

[ibd]

Lower glutamate and GABA levels in auditory cortex of tinnitus patients: a 2D-JPRESS MR spectroscopy study

For me, the following takeaways:

• Some of the results, i.e., w.r.t. glutamate concentrations, contradict the expectations, and the detailed results don't agree perfectly with earlier studies, so I would consider the statistically observed correlation to be not that strong and/or clear.
• This reinforces the importance and possible relevance of drugs that have an effect on either of these neurotransmitter levels. Indeed, several threads on this forum support this, for example there are threads on Gabaline, Pregabaline, "GABA CALM" products, and others.
• It could explain what some people have experienced with Ketamine, as that is known to change brain glutamate levels, albeit only temporarily (effect subsides after a few hours).

We performed magnetic resonance spectroscopy (MRS) on healthy individuals with tinnitus and no hearing loss (n = 16) vs. a matched control group (n = 17) to further elucidate the role of excitatory and inhibitory neurotransmitters in tinnitus. Two-dimensional J-resolved spectroscopy (2D-JPRESS) was applied to disentangle Glutamate (Glu) from Glutamine and to estimate GABA levels in two bilateral voxels in the primary auditory cortex.

Results indicated a lower Glu concentration (large effect) in right auditory cortex and lower GABA concentration (medium effect) in the left auditory cortex of the tinnitus group. Within the tinnitus group, Glu levels positively correlated with tinnitus loudness measures. While the GABA difference between groups is in line with former findings and theories about a dysfunctional auditory inhibition system in tinnitus, the novel finding of reduced Glu levels came as a surprise and is discussed in the context of a putative framework of inhibitory mechanisms related to Glu throughout the auditory pathway. Longitudinal or interventional studies could shed more light on interactions and causality of Glu and GABA in tinnitus neurochemistry.

 

[IndyMLVC]

As I've mentioned elsewhere: I've had 10 IV Ketamine sessions in the last year and a half for depression. Never had any impact on my tinnitus. In fact, it got louder at times when I was on my trip.

Totally anecdotal. Hope it helps someone but it didn't help me.

 

[Nick47]

Yes, the significantly large effect of reduced Glutamate is a surprise. Although this is the auditory cortex only. There are other areas involved, primarily the DCN. What are the neurotransmitter levels in tinnitus patients like there?

 

[CRGC]

An interesting detail about that study is that it examined individuals with tinnitus and no (measured) hearing loss. I wonder if this could explain why drugs acting on Glutamate/GABA appear to help certain people on here but not others. Could it be that if one has hearing loss / damage, then simply playing with Glutamate/GABA is not enough to reduce tinnitus?

 

[SmallRonnie]

As I've mentioned elsewhere: I've had 10 IV Ketamine sessions in the last year and a half for depression. Never had any impact on my tinnitus. In fact, it got louder at times when I was on my trip.

Totally anecdotal. Hope it helps someone but it didn't help me.

I took a total of 2 grams of Ketamine in the past two weeks and my tinnitus is the exact same now again.

It doesn't work for anyone as far as I've seen.