There is very little scientific literature on this, but more so in the last 10 years or so.

The only technique I heard anecdotally reported on the internet is "image streaming." I tried this but had no success.

From my experience it seems that the hypothesis that an alert state suppresses visualization is correct (at least for me) as I can recall very vivid imagery after waking from a dream, and also during lucid dreaming (so it seems CBT or similar should work but don't seem to at least for me).

There are also seem to be other modalities of aphantasia in the other senses (sound, smell, touch). I learned that I have a high vivid imagination for my sense of smell in an alert state (with effort I can have the same vividness of smelling imaginary pizza as if it was in actually front of me) despite scoring the lowest on the scale for visual imagery.

Would be very curious to hear how your imagination of smells compares to your imagination of sounds. I have what I suspect is a very high imagination of sounds, but I've always found it difficult to discuss the topic with other people who identify their strongest imaginative capacity as either visual or auditory.

On a scale of 1-5:

Smell:5 (can smell pizza as if it is in front of me but requires effort)

Sounds:2 (can very faintly hear single notes/a melody I imagine but nothing more complex with essentially no effort, but as I’ve played music most of my life this is not surprising)

Vision:1 (blackness)

Just for curiosity's sake, when you imagine smells, do they tend to be accompanied by some level of taste as well, given that the two senses are so closely linked?

I’m aware of how closely they are linked (flavor being mostly from smell) but I’d say no.

In recalling my psychology classes I wonder how much higher correlation could be drawn in studies done on the effectiveness of advertising for food (if you could partition the cohort by such measures I imagine there is an effect where not only during the advertisement it is more effective, but effects of the stimulus days afterwards might be also much more stronger if you can effectively smell the food from an advertisement everyday you recall it afterwards)

As a fellow aphant, I'll be following this with great interest!

If you want to change your brain, all power to you. But it seems wrong to call this a "cure" when aphantasia is such a common human experience.

I'm sort of halfway between Scott and Caplan on the subject of mental illness being preference. In this case my preference is that I can create memory palaces and currently I cannot, so I'm calling it a cure.

Good luck!