Following lines base upon the great book of Dr. Temple Grandin „Animals in Translation“ – http://www.grandin.com/inc/animals.in.translation.ch3.html is a short excerpt, as well as various papers about brain morphology with Klinefelter’s syndrome, ADHD and autism.

Please correct me if I interpreted outcome of the book wrong:

According to the three-brain-theory, humans and animals have exactly the same brain but humans have a wider frontal part of the brain where the executive functions (logical thinking, etc…) sit. If the frontal part is damaged, the animal brain in us will dominate, with simple emotions like in animals. That’s the reason for which autists (and possibly Klinefelter’s) have a greater relationship to animals than „normal people“. I also know from autists who don’t become warm with animals and Klinefelter’s, too. If you know a Klinefelter, you know an individual Klinefelter ….Children are similar to animals, they do not manipulate or complain about you having too much money. They love you the way you are. A cat or a dog does so, too.

I found out that, according to Temple Grandin, the frontal lobes with autistic people are of normal size but they work as if they were smaller. In contrast, scientists found out that frontal lobes in Klinefelter’s are smaller than in average. So there is a ‚real‘ damage to the brain. Temple Grandin, however, also highlights the advantage of differently working cognitive and executive functions. It’s the reason for which people with Klinefelter’s syndrome (and autists) tend to have higher sensitivity to noise and maybe also to other features of their surroundings (I’m not sure about that point, however, but some of them are able to smell much more than usual). They also perceive much more details than a big picture which might be good when you have to detect errors or things which could be a danger but are often perceived as bad since you are distracted then (–> AD(H)D) and you have problems to concentrate on a certain task. With normal people, frontal lobes are either wider or work the usual way, that is, people don’t see what they do not expect to see, they see the big picture but not the details in it. That’s a major advantage when you want to focus on something (especially at work when phones are ringing and there is hectic pace in the background) and a major disadvantage overlooking details which may lead to errors or bring you in danger. Speaking for myself, I’m able to recognize the tiny cloud details in the sky which tell you about a probable (sudden) weather change. I use it as a big advantage not to be surprised when hiking in the mountains. Most people don’t know there are even signs for a weather change and later you will hear them complaining about „the storm was completely unexpected!“

Anyway, there appear to be some similarities between brains of people with XXY, ADHD and autism:

• In all conditions, amygdala is smaller, and the neocortex is thinner than with normal people.
• Frontal lobes are only smaller with Klinefelter’s and ADHD’s but of normal size with autists (but they use it as if they were smaller which could be the main difference between most Klinefelter’s and autists).
• Cerebellum (steering motoric skills) is smaller with both Klinefelter’s and autists.
• Some parts of the neocortex like the left temporal region seem to grow and therefore improve with testosterone replacement (Steinman et al.,2009) influencing positively verbal fluency and attention.
• Other parts reveal contradictory results of testosterone therapy in studies.

As there is a wide range of results and barely a unique (behaviorial) feature all Klinefelter’s are sharing, I’d like to emphasize here that Klinefelter’s is not the same as autism! The genotype 47,XXY does not imply having both autism and AD(H)D, too.

Some brain features seem to be quite similar, but not with every 47,XXY man. Maybe some of us show more similarities with autistic/animal brain and develop a closer relationship to animals but this must not be true for all of us. We’re still individuals. It’s another reason for which I prefer to speak of Klinefelter’s spectrum than of a syndrome in the future.

Last but not least:

The research I do here as a concerned person results from deep curiousity. I know very well that I’m fishing in foreign water, and I certainly ignore much of the underlying mechanisms leading to different brain morphology as the gene topic is really complicated. I just try to puzzle out the story of behavior and emotions as far as I am able to do it and I’m looking forward to any comments, criticisms and help of scientists or specialists who might have a deeper insight into that topic.  Since I did not finish Temple Grandins book yet, I’ll provide you further information about everything which might help us. And please note: I speak for myself, I honestly try not to generalize like it’s been done a long time with stigmatizing it as Klinefelter’s syndrome. By approaching the subject in a natural science thinking manner, bad outcome looses its scare factor and good outcome (like positive characteristics which can be observed) might be confirmed beyond doubt.