Reading Arabic letters means paying attention to detail and where dots are located, especially when you first learn the language. Not an issue after that.

I fail to see how that is "hard for the brain", when you know that the Arabic alphabet is limited to 28 letters.

The OP should have looked at learning languages that have thousands of ideograms (Japanese Kanji, Chinese, etc...)

Abstract of reference paper here: http://www.ncbi.nlm.nih.gov/pubmed/14744200 It s a shame no full text of this research is freely available.