As a psychiatrist, many people have recently asked me what I thought of Donald Trump.

Numerous observers have called him "narcissistic", but remain puzzled by why he says what he does, and what he will do if he loses the election. Recently, some commentators have started describing him as a "sociopath". But a lot of confusion persists about what this second term means exactly. Increasingly, the term is critical to grasp.

As a psychiatrist, I have treated patients with sociopathic personality disorders. What distinguishes them, generally, is a lack of remorse or guilt for violating social norms - concerning truth or the others' rights. They are Incredibly convincing liars. Many are con-men. They possess uncanny abilities to convince others of their honesty, and truth.

It is unethical for me to diagnose people I haven't personally interviewed (such as Trump). But psychiatrists can provide general information about diagnoses, enhancing public awareness about psychiatric diagnoses.

With increasing research and clinical, the concept of sociopathy has shifted. Once considered, "psychopathy," more recently, the Diagnostic and Statistical Manual 5 (or DSM5), has described the phenomenon as "Antisocial Personality Disorder" (ASPD):

A pervasive pattern of disregard for and violation of the rights of others...as indicated by...failure to conform to social norms...Deceitfulness...repeated lying...or conning others for personal profit or pleasure...Impulsivity or failure to plan ahead, Irritability and aggressiveness...Reckless disregard for safety of self or others, Consistent irresponsibility...Lack of remorse...being indifferent to or rationalizing having hurt, mistreated, or stolen from another.

Approximately 1-4 percent of the general population, and about 8 percent of psychiatric outpatients have ASPD, with males 3-5 times more likely than women. It varies in severity, from mild to severe, and in which of these traits are most prominent.

But it's notoriously difficult to treat or alter. Generally, sociopaths are uninterested in changing long-standing patterns of interaction, or getting treatment. These traits often persist over decades, despite social pressures to change.

Sociopaths are concerning because they can easily fool us. Studies show we only detect lies half the time -- no better than chance. As we see more of their get information from others, these traits can become clearer. But by then, they may have already swindled us.

We may mistakenly believe that once sociopaths get what they ostensibly want -- a particular job or sexual partner -- they will be satisfied, and stop being sociopathic. Alas, that is rarely the case. Rather, such personality traits endure.

By contrast, narcissism, as defined by DSM5, consists of "impairments in self function" -- either identity ("excessive reference to others for self-definition and self-esteem regulation") or self-direction ("goal-setting is based on gaining approval from others"), with "impairments in interpersonal functioning" -- either empathy or intimacy ("relationships largely superficial and exist to serve self-esteem regulation..little genuine interest in others...").

Sociopathy and narcissism thus differ in key ways. Narcissism commonly leads people to exaggerate their accomplishments, but sociopathy is more likely to prompt wholesale disregard for the truth.

Individuals may also have mixes of both of these personality disorders or traits. After all, the DSM lists only 10 personality disorders; but no two people are exactly alike. Even if individuals share certain personality traits, the intensity and manifestations vary.

Personality traits and disorders, also occur along spectrums from minimal to moderate to severe.

Countless people display these traits when these don't rise to the level of disorders -- which, by definition, significantly impair functioning at home or work. Many people feel depressed after major disappointments. But others commit suicide. Before taking a test, many of us feel nervous, but anxiety cripples some people. I once treated a patient who was so blocked by anxiety that she couldn't cross the street unless someone accompanied her. She did all her Christmas annual shopping downstairs from her apartment.

These disorders and traits, when present, also interact with other aspects of our personalities -- shyness, outgoingness, and intelligence -- whether verbal, mathematical social or emotional. Hence, a person can have traits of sociopathy, and have diminished regard for the truth or social norms, but be a brilliant novelist, painter or politician.

All this is to say that these issues are complex but can provide a framework that can help in understanding key aspects of people we meet and their behavior, and making sense of them -- to recognize that our individual emotional responses to them may say something about them - not just us, and that these categories may endure.

Awareness of categories of personality traits may also help us, as a country, make the best possible decisions about who we should choose as our national leaders.

Psychiatrists cannot diagnose individuals we have not met and interviewed, but we can try to educate voters as they make their own decisions.