It's not an attempt to decieve. With the stigma of mental illness, it's a protection for yourself to not include someone in the information. If there are reasons to not tell them, such as you know they don't believe in mental illness and will only attack you for telling them, then it's better to keep it to yourself.

Not everyone needs to know. The majority of my family doesn't even know, because I know there isn't anything they can do and will just be judemental.