09/04/2013 06:52 BST | Updated 08/06/2013 06:12 BST

Women, Power and Margaret Thatcher

At the height of her political power, elderly people with dementia remembered that Margaret Thatcher was prime minister more readily than that Queen Elizabeth was their queen. Her own declining years unfortunately were plagued by dementia and this remarkable woman will be given a state funeral of entirely royal proportions.

Few women in history have achieved the political, social and economic influence that Margaret Thatcher did, and whether you disagree with what she did or not, by any measure she was a historical 'great'. Above all, she showed that biology had not handicapped women from achieving dominance in the human tribe and that the barriers to women becoming leaders were primarily social and psychological, not Darwinian.

She was a dominant politician, but whereas in a man this would have often have been seen as a virtue, her gender meant that this tough leadership style was often negatively framed as a particularly female type of hectoring.

In accordance with this view, she supposedly interrupted interviewers much more than other politicians, but in fact when psychologists counted her interruptions, she did not. What she did do, was to complain more when she was interrupted, thus giving the impression to sympathetic viewers that she was being badly treated by biased interviewers. She reinforced this successful strategy by tending to personalize issues and to take some critical questions as accusations.

She tended to black and white thinking: she used words like "trend" ,"possibly", "perhaps," and "sometimes" much less than did other world leaders when talking about foreign policy, and the words "always", "never", and "absolutely", much more.

This led her to be assessed as having a cognitively simple, black and white view of the world, yet within a year of the Irish Republican Army almost killing her with a bomb in her hotel in Brighton, she had signed the Anglo-Irish agreement, a key element in the start of the ultimately successful peace process.

Of course, she also fuelled the IRA campaign by her rigid black and white stance in refusing to give their hunger strikers special status in the prisons, yet at the same time her government were holding secret talks with the IRA.

Her apparent cognitive simplicity, in other words, may have been more a stylistic feature of a populist leader who was extremely focused on action.

The best leaders enjoy power because if they don't, they too-easily succumb to stress and self-doubt. Power has strong anti-anxiety and anti-depressant properties and equips leaders to take unpopular decisions and to follow a course of action through the complex forest without being distracted by individual trees. Power can make you smarter and the Irish prime minister Enda Kenny's hugely increased performance since becoming Taoiseach is an example of this.

But no leader can survive too much power for too long and the eleven years of dominance in her country took its toll on Margaret Thatcher's judgment and abilities.

While some power can embolden and smarten, it very easily tips over an inverted-U curve where its chemical effects on the brain disrupt its fine tuning. Among the symptoms are narcissism, loss of empathy, risk-blindness and a mental tunnel vision that comes from over-focus on one's own personal goals.

Margaret Thatcher apparently was a great admirer of Tony Blair, and vice versa, which is not surprising since both these talented people suffered serious distortions of their cognitive and emotional functions as a result of the power they managed to garner over long periods in office.

Both were dragged from their hunting horses not by the dogs of the electorate, but by the hounds of their colleagues.

Power's action on the brain has many similarities to drugs like cocaine, and can cause similar changes to the brain, including, in extreme cases, a sort of addiction to power. Margaret Thatcher found it exceedingly difficult to live without this drug and harbored a bitter and unforgiving resentment against the colleagues who brought her down until dementia came over her.

Margaret Thatcher taught us that women leaders are not immune to the distorting - and sometimes corrupting - effects of power that we have seen throughout the ages in men. My own research of the scientific literature suggests that women may be somewhat less at risk for this, and that we need many more women in positions of power, not just in politics but also in business and other domains of life.

But power is a strong and dangerous drug and we need all the mechanisms of democracy and good governance to tame and constrain our leaders, whether they be men or women.