Annoying co-workers, deceitful colleagues and egocentric clients can make the job of the meeting professional a challenge. But nothing could be worse than dealing with a psychopath.

The word "psychopath" scares people. Psychopaths are the subjects of newspaper headlines and television crime shows - cold-blooded killers, pedophiles and ruthless con artists - people we hope to never meet in our own lives. Yet, research shows that about 1 percent of the world's population has psychopathic tendencies. The fact is that not all psychopaths are violent and dangerous; rather, the headlines that raise our awareness have skewed our understanding of who they are and what they're like. If one in 100 individuals you meet in any given day could have psychopathic tendencies, how can you tell if your colleague is a psychopath or just someone with a disagreeable personality? An important first step in defending yourself is to learn about and understand just what makes someone a psychopath.

Psychopathy is a personality disorder defined by 20 traits and characteristics. Studies of the personalities of criminals over the past 30 years, as well as many individuals in the general population, form the basis for this research.

To make these traits and characteristics easier to understand, we can group them into four domains based on how they play out in daily life. The interpersonal domain defines how someone with a psychopathic personality disorder comes across to other people. When you first meet a psychopath, he or she seems to be very charming, often charismatic and quite likable. Psychopaths have excellent oral skills and will impress you with their knowledge in many areas, convince you that their view is the correct one and entertain you with humorous, and sometimes pleasantly outlandish, stories. But if you spend some time with one, you'll eventually notice the grandiose style seems a bit too superficial and the air of superiority and the sense of entitlement a bit too much to take. If you dig deeper, you'll discover that most of what you know about them is just a mask or façade. The façade they create provides the cover they need to get what they want: money, power, sex, status. Think Dr. Jekyll and Mr. Hyde. Once you suspect that someone is not who they appear to be you should be careful not to take the relationship any further. But, if this is a work situation - whether a co-worker, client, vendor or property owner - you may have to deal with him or her anyway.

Psychopaths are master manipulators, investing notable energy and skill in creating and then preserving their masks. Their masks are successful because they tailor them to their targets, lying to get what they want. Pathological lying, even about insignificant things, is a core trait of the psychopath.

How can we be fooled? The positive first impressions psychopaths make are prone to last far too long because it is human nature to trust our initial judgments of people. We also want to give people the benefit of the doubt. We filter in information that supports our initial impressions, and filter out facts that don't fit. Should any doubt arise in our minds, the psychopath is there with a convincing explanation or plausible excuse that soothes any concerns we may have had. Over time we come to believe we really know this person, and trust him or her.

Psychopaths also lack the capacity to feel the wide range of human emotions the rest of us experience; they suffer from affective (emotional) poverty, which is the second domain. Neuropsychologists have discovered that the emotional parts of a psychopath's brain work differently than the emotional parts of a non-psychopath's brain. Words, acts and feelings don't connect in their minds. For example, when you lie, or when you hurt someone, you feel remorse or regret, and believe you should apologize or make it up to the person somehow. Not sleeping at night when you've done something wrong is a symptom of a working conscience, which the psychopath lacks. So is fear that you may get caught should you break the law. On the positive side, most people take pleasure in art, music, professional accomplishments and achievements of their friends. Psychopaths do not have this capacity for human emotion. In fact, other than anger, rage and frustration, they rarely feel anything akin to normal human emotions. People who do not interact regularly with psychopaths will find this concept difficult to understand and accept, especially since psychopaths will mimic emotions in order to manipulate their targets.

Besides lacking empathy and sympathy for others and being unable to feel remorse for anything wrong they may do, psychopaths are unwilling to accept responsibility for their actions. They readily blame others for everything that goes wrong. Should you be in their lines of fire, you may find yourself a convenient scapegoat.

The third domain, lifestyle, deals with how they live day-to-day. Theirs is an impulsive, irresponsible lifestyle. They lack goals and are unwilling to expend the effort needed to achieve anything of significance. However, lists of major accomplishments (faked), high-status positions (exaggerated) and significant scopes of responsibility (distorted) will fill their resumés. Their irresponsibility can be frustrating, especially if you are conscientious about doing your job and doing it well. Their impulsivity can also be dangerous as they don't care about the impact of their actions on co-workers, clients or their employers. They do enjoy handling "the big picture" and schmoozing with clients, but details bore them and they leave important work undone. Yet, expect them to take the credit for anything you've done, even if they weren't even involved.

Because psychopathic tendencies can develop early on in life (both nature and nurture are involved), psychopaths often have personal histories filled with antisocial behavior, the fourth domain in our model. Examples include early adolescent problems (such as delinquency, truancy, shoplifting, disturbing the peace, public intoxication) as well as later adult antisocial acts (such as fraud, excessive speeding violations, spousal abuse). Their inability to control their behavior in socially acceptable ways seems rooted in their belief system (they are above the law) and how their brains are organized (they don't feel fear and suffer no guilt).

Interpersonal influence, emotional poverty, aberrant lifestyle and antisocial tendencies together make up the psychopath's profile. People who demonstrate most of these characteristics tend to end up as criminals and in prison. The corporate psychopath, however, has a muted profile. He or she is typically high on interpersonal and emotional domains (they have the psychopath's personality), but score only moderately on the lifestyle and antisocial domains (they have "learned" how to better fit into society and corporate life). Unfortunately, they can incorporate many seemingly "effective" traits of leadership into their masks. Yet, all the while they may be working behind the scenes to sabotage projects, ruin careers and even commit corporate fraud.

The best advice if you suspect that you're dealing with a psychopath?
Avoid contact as much as possible, document everything, follow-up on all details and keep superiors in the loop. It's tempting to trust people who appear to be too good to be true, but remember that often they are.