Obesity linked to brain shrinkage and dementia

THE dangers of obesity are very well known. Being overweight is associated with an increased risk of coronary heart disease and stroke, the two leading causes of death in the Western world. Gout is more common in overweight people, with the risk of developing the condition increasing in parallel with body weight. Obese people are twice as likely to develop type 2 diabetes as those who are not overweight, and being overweight is also associated with several types of cancer. The list goes on…

Less well known is the effect of obesity on the brain. In the past few years, however, it has emerged that being overweight in middle age is linked to an increased risk of Alzheimer’s Disease and other forms of dementia. Two new studies strengthen this association: the first, just published in the Annals of Neurology, shows that abdominal fat is linked to reduced brain volume in otherwise healthy middle-aged adults. The second, published last month in Proceedings of the National Academy of Sciences, shows that this reduction is associated with a common variant of an obesity-related gene.

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Surgery on conscious patients reveals sequence and timing of language processing

THINKING of and saying a word is something that most of us do effortlessly many times a day. This involves a number of steps – we must select the appropriate word, decide on the proper tense, and also pronounce it correctly. The neural computations underlying these tasks are highly complex, and whether the brain performs them all at the same time, or one after the other, has been a subject of debate.

This debate has now apparently been settled, by a team of American researchers who had the rare opportunity to investigate language processing in conscious epileptic patients undergoing surgery. In today’s issue of the journal Science, the researchers report that the brain processes lexical, grammatical and phonological information in a well defined sequence that lasts less than half a second, and that a single language centre known as Broca’s Area is involved in all these tasks.

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