Low T (testasterone).... I've seen it mentioned on the forum... what is it and how does it affect/coincide with ADD/ADHD?

I'am a non-ADD/ADHD spouse of an ADD-I(inattentive)...  I feel it's more ADHD though...but that's not what I'm asking about. 


My question, another post mentioned having a "low T" test and taking testasterone shots.   I was interested in learning more about this as I heard that a man with low testasterone can be misdiagnosed or treated for his ADHD/ADD as the main problem or contributing problem his low testasterone levels....which have a similar affect as ADD.

Can anyone else tell me more about this Low Testasterone levels and the "low T test"?