Lyric discussion by slinadoed 

Cover art for True lyrics by Spandau Ballet

I have to agree with the other two posters that have said the song is about drugs and drug addiction.

"I bought a ticket to the world, But now I've come back again".

A ticket to the world is the drugs, but now I've come back again is him saying his high has warn off.

"Why do I find it hard to write the next line, Oh I want the truth to be said"

He finds it hard to admit that he is an addict, but he wants the truth to be told.

"With a thrill in my head and a pill on my tongue"

Pretty much speaks for itself. He has his drugs again and it thrilled about it.

"Dissolve the nerves that have just begun"

The drugs are relieving his anxiety.

"Listening to Marvin (all night long)"

As another person said this shows that this person has an injured soul. His addiction is hurting his soul.