There are some studied done about it. Here is the list of them
Effectiveness of cigarette warning labels
Perceived Believability of Warning Label Information
Do Cigarette Warning Labels Reduce Smoking?
Another study came up with
Approximately one fifth of participants [by the way there are 616 adult smokers] reported smoking less as a result of the ...
If an average Joe and Jane Smoe think they discovered a treatment that works for them but it's not currently used by conventional medicine and they want to validate it for effectiveness and safety, they can ask an experienced doctor, in case of psoriasis a dermatologist, for an opinion. The doctor can then judge if the treatment deserves further ...