We present and analyse a model of opinion formation with dynamic confidence in agent-mediated social networks where the profiling of agents as leaders or followers is possible. An opinion leader is specified as a highly self-confident agent with strong opinions. An opinion follower is attracted to those agents in which it has more confidence. In our model, an agent i increases its confidence in another agent j based on how well j?s opinion meets the criteria specified in i?s mind-set. A mind-set represents the set of beliefs, attitudes, assumptions and tendencies that predetermine the way an agent evaluates a received opinion. It is observed that the opinion formation in a group of persuadable agents, with similar confidence in each other, can easily lead to groupthink with agents following each other and one (or some) following the opinion of a single opinionated agent (i.e. an opinion leader). However this can be prevented by having at least one more self-confident, opinionated agent with an alternative opinion. This shows that divergent opinions from opinionated agents inhibit consensus. Furthermore, it is seen that once an equilibrium in the opinion formation has been reached, paradigm shifts can occur as the result of the sudden appearance of alternative opinion leaders.