Living for three months in New York has made me feel like I have an extra decade to live.
Just before I came to Manhattan, I gave a TEDx talk on 'the Perfect City" where I argued that just as cities make people walk faster - the bigger the city the faster they walk - so they may also help people think faster and more creatively. Indeed, the rate of innovation and the more creative industries scale with the size of the city.
But I hadn't expected to experience first hand what feel like the quasi-neurological effects of living in New York which strike me as encompassing these three things: excitation, expectation and empowerment.
Before expanding on these, a word on my research here with my colleague Yaakov Stern at Columbia University, who coined the term 'cognitive reserve', to capture an as yet not understood process which means that the more education, rich social networks and/or mental stimulation you have, the less likely you are to be diagnosed with Alzheimer's Disease. This is in spite of some well-educated or well-stimulated cognitively apparently normal people having Alzheimer's-type pathology lurking in their brain tissue.
Whatever cognitive reserve is, it is remarkable to see how social artifacts like education are able to diminish the grim linkages between the molecular chemistry of the brain on the one hand, and the functions of memory and awareness on the other.
One possible mechanism for this - still only a hypothesis that I recently proposed in the journal Neurobiology of Aging - is that education and stimulation repeatedly trigger a chemical messenger in the brain called noradrenaline (also called norepinephrine) which, it turns out, has remarkable properties, including quelling the toxic effects of a key Alzheimer's pathology on surrounding healthy brain cells.
Noradrenaline in moderate doses also acts as a sort of fertilizer, helping the brain make new physical connections between cells and even stimulating new brain cells to grow. What's more, it also 'rescues' other crucial cells for other key chemical messengers in the brain such as dopamine and acetylcholine, which are critical for attention, thinking and memory.
Whenever you are presented with a challenge or a problem, whenever you learn something new and each time your are surprised by something, your brain releases noradrenaline. A lifetime of challenge, problem-solving, learning and novelty is what education buys you. And it may be buying you a lot more.
But education is not the only source of noradrenaline release in your brain: cities like New York are engines of novelty - you are constantly surprised by new things and you really can feel your brain almost physically responding to this.
The late writer Christopher Hitchens wrote that when you come to New York, you go to bed an hour later and wake up an hour earlier, and I can confirm this anecdotally myself. Noradrenaline is the key 'wake-up' drug of the brain and it may be that the shear repeated novelty and stimulus of this great city is chemically flooding my brain with this brain-protecting substance.
But of course a caution is needed. Like many of the brain's chemical messengers, noradrenaline has a 'Goldilock's zone' where too much and too little are bad for brain function, while the 'just right' range in the middle helps the brain function really well. And New York like other cities can be very stressful for some people, particularly if they are on the edge financially or emotionally. For them, there may be no positive effects on their brain function and indeed the reverse may be true.
So what are these 'three E's of Manhattan? The first is excitation - that constant novelty and pace that I have little doubt increases noradrenaline secretion. Mice who are put into stimulating environments where the objects in their cages are changed frequently develop better memory and even grow new brain cells. What's more, it is the noradrenaline which novelty triggers which seems to be the link that causes its beneficial effects.
The second is expectation. Older people in New York don't seem to think themselves old. Some have to keep working into their seventies and even eighties for harsh financial reasons, but others seem to have cast off the psychological limitations of what people of a certain age are supposed to behave like. Seventy-year olds dance on roller-blades in central park, before going back to their appartments to decide on their next career move.
Of course this is a wealthy place and wealth opens opportunities that hardship close, and wealth offers the third 'E' - empowerment. In my book The Winner Effect , I showed how money, power and success change brain function by increasing dopamine activity and hence making people mentally sharper, more motivated and bolder.
New York is full of mentally sharp, highly motivated and bold people in their seventies, eighties and above, who appear to me to be empowered by a sub-culture where people are empowered by their age rather than being disadvantaged and mentally disabled by a youth-worshiping agism which prevails in many developed countries.
So even as the pharmaceutical industry desperately searches for a cognitive enhancing drug which will delay Alzheimer's Disease among the over-fifties - I have my own, which may be the modern equivalent of a 19th century Alpine sanitorium trying to stave off the killer of that era, tuberculosis. My "Kur" for our 21st century cognitive aging epidemic is to spend 3 months in New York.
And the challenge is to find ways of re-creating this experience across the world, which any city worth its salt should be able to do.