Mongoose return value to function

How can i return after a Mongoose find a variable to the function above? This is my code:

function getData(user, token) {
    Collection.findOne({username:user, accessToken:token}, function(err, profile){
        if(!profile) {
            return false;
        }
        return true;
    });
}

Because it is a function can't i return a value back to getData(). So i have tried to do this with global variables, that worked but i didn't like the way that i had to make a global variable for all the Mongoose find's. Is there an other or better way to return a value back to the function getData?