A spectacular case of psychosis, rather oddly described as ‘Methamphetamine Induced Synesthesia’, in a case report just published in The American Journal on Addictions.
The report concerns a 30-year-old gentleman from the Iranian city of Shiraz with a long-standing history of drug use who recently started smoking crystal:
Six months PTA [prior to admission] (October 2009), he started smoking methamphetamine once a day, and gradually increased the frequency to three times a day.
Two months PTA (January 2010), he developed symptoms of auditory and visual hallucinations (seeing fairies around him that talked to him and forced him to conduct aggressive behavior), self-injury, and suicidal attempts.
He developed odd behaviors such as boiling animal statues. He was hearing the voices of colors, which were in the carpet. Colors moved around and talked to each other about the patient. He also saw the heads of different kinds of animals gathering on a board, and they talked to him.
Finally, his mother brought him to the emergency room of Ebnecina Psychiatric Hospital in Shiraz.
The authors are using the term ‘synaesthesia‘ very liberally as it usually refers to an experience in one sense automatically triggering sensations in another – such as numbers having specific colours or tastes.
I’m not sure that ‘hearing the voices of colours’ necessarily qualifies as this could as much a delusion (a distorted belief) or a hallucination (that isn’t specifically tied to seeing the colours) rather than a genuine synaesthetic experience.
As the authors didn’t investigate any further and only have the gentleman’s word for his experiences, it’s a little hard to say.
However, it’s also worth noting that our concept of synaesthesia is no longer tied to ‘crossing of the senses’ as synaesthesia for increasingly meaningful things is being discovered.
Only recently, two confirmed and tested cases of ‘swimming-style synesthesia’ were reported in the journal Cortex where different colours were reliably triggered by the sight of people doing different swimming strokes.
Link to locked case report of ‘meth-induced synaesthesia’.
Mind Hacks 
I agree, the term synesthesia was used too liberally in this study. If we name every unusual association with the word synesthesia, the word will soon lose meaning. I am afraid that this is has already started to happen.
I don’t think the problem is their liberality at all, but their lack of corroborative evidence. It’s _possible_ that this is synaesthesia, or it could be a delusion. They did not collect enough evidence to separate the two.
As an example of a verified synaesthesia that would be equally “liberal,” consider object-personality synaesthesia. In this form, a young woman perceived letters, numbers, and shapes as having rich personalities and relationships.
Over six months of careful study were required to confirm that this was legitimate synaesthesia and not a delusion.
http://www.mitpressjournals.org/doi/abs/10.1162/jocn.2007.19.6.981
As for the word “losing meaning,” there are 61 types, and any definition ought to include them all or present a scientifically valid reason for an exclusion.
http://onlinelibrary.wiley.com/doi/10.1348/000712610X528305/abstract;jsessionid=58BB19ECC3DFF1065D3650BB2A209B56.d03t04