April 01, 2007

Abnormalities of brain structure and function in GADHD

One of my former students has sent me a preprint of an important paper, due to be published next week, which uses modern brain imaging methods to provide a fascinating new perspective on metagrammatical ideation. In particular, this research helps us to understand why some people feel so strongly about perceived grammatical faults which they nevertheless understand so badly. The paper is J.C. Brother, Dewey, F.X., Cheatham, M., and Howe, C., "Volumetric Analysis and Glucose Metabolic Mapping of the Anterior Cingulate Gyrus in Patients with Grammatical Attention-Deficit Hyperactivity Disorder", Psychiatric Neurobiology, [forthcoming].

I'm late submitting a paper of my own for an upcoming workshop, and behind on a dozen other commitments, so I don't have time to go over this research in detail today . Anyhow, I should wait until you can read the Brother et al. paper for yourself, and it wouldn't be right for me to put the whole thing on line before its formal release. But I don't think the authors will mind if I give you an advance peek at the abstract:

Pullum et al. [1] have identified a behavioral syndrome, grammatical attention-deficit hyperactivity disorder (GADHD), which is characterized by difficulty in focusing on linguistic structure, paradoxically combined with obsessive and affectively intense delusions about widespread violations of "rules of grammar". In this study, we compared 30 patients diagnosed with GADHD to 30 age- and sex-matched controls, using magnetic resonance imaging (MRI) and positron emission tomography (PET) to measure volumes and metabolic activity throughout the cortex. The volumetric analysis found that patients with GADHD had significant bilateral atrophy of parts of the anterior cingulate gyrus, with Brodmann areas 24 and 32 reduced in volume compared to the control subjects (634 ± 232 vs. 399 ± 170 mm3 and 6837 ± 1114 vs. 4171 ± 1572 mm3, respectively) while the metabolic analysis showed that the same areas nevertheless had significantly higher glucose metabolic rates per unit volume (CMRgl of 6.17 ± 1.23 ml per 100 g of tissue mass per minute in the GADHD patients vs. 4.66 ± 0.97 in the controls). These results are interepreted in terms of current theories of attention, reasoning and emotion.

Posted by Mark Liberman at April 1, 2007 06:29 AM