I've interviewed probably a hundred CEOs and, with few exceptions, my observation has been "the bigger the company, the bigger the jerk." CEOs, especially in big companies, tend to be self-centered, clueless, overconfident and utterly convinced of their own genius.

I've always assumed that those character flaws drove them to become CEOs, but that's not the case. To climb the ladder or grow a company, would-be CEOs need empathy (to work well others) and humility (to put their own ideas aside in favor of those of their superiors).

Apparently, CEOs become jerks after they've achieved their goal because the exercise of power (corporate or political) causes measurable brain damage, according to a study conducted at McMaster University in Ontario.

As explained in a recent article in The Atlantic, when neuroscientist Sukhvinder Obhi

"put the heads of the powerful and the not-so-powerful under a transcranial-magnetic-stimulation machine, he found that power, in fact, impairs a specific neural process, 'mirroring,' that may be a cornerstone of empathy."

While it may seem strange that exterior events can cause changes in your brain structure, the human brain possesses the characteristic of neuroplasticity, which causes it to constantly "rewire" itself. Using biz-blab, for example, actually makes you stupid.

Because the exercise of power over large groups of people is not part the human DNA (which is optimized for cooperation in small groups), it's not surprising that it has a debilitating effect on brain function.

The results of Obhi's study are echoed twenty years of lab and field experiments by psychology professor Dacher Keltner at UC Berkeley, who found that people

"under the influence of power... acted as if they had suffered a traumatic brain injury--becoming more impulsive, less risk-aware, and, crucially, less adept at seeing things from other people's point of view."

As you might expect, the amount of brain damage (and consequent bizarre behavior) increases when people in power surround themselves with toadies and sycophants who adapt and cater to the big-wig's whims and moods.

According to a landmark article in Brain: A Journal of Neurology, in the most pronounced cases, the brain damage can create a condition called "Hubris Syndrome" which manifests itself as any (or all) of the following behaviors,

Sees the world as a place for self-glorification through the use of power

Has a tendency to take action primarily to enhance personal image

Shows disproportionate concern for image and presentation

Exhibits messianic zeal and exaltation in speech

Conflates self with nation or organization

Shows excessive self-confidence

Manifestly has contempt for others

Loses contact with reality

Resorts to restlessness, recklessness and impulsive actions

Displays incompetence with disregard for nuts and bolts of policy making

I don't know about you, but I'm not finding it very difficult to find examples of obviously brain-damaged behavior in recent business news (Kalanick, Stumpf, Mayer, etc.) Indeed, it's surprising that many big company CEOs manage to behave (more or less) normally.

Power-wielders who don't want to suffer from brain damage (and the consequent hubris and failure) must take positive steps to avoid it. Experts suggest the following:

Keep people in your life who "knew you when" and know how to pop your bubble of pretension. Encourage and reward honesty, but discourage and penalize flattery, from employees and advisors. Avoid the trappings of power and privilege that only serve to further isolate you from normal human interaction.