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An MRI study has shown variations in patients with different types of dementia, according to researchers in Japan. They found that observation of atrophy, shrinkage, of different parts of the brain - the amygdala or anterior entorhinal region - could be important in providing a definitive diagnosis of very mild dementia and distinguishing it from normal elderly effects. Hiroshi Ishii, Kenichi Meguro, Satoshi Yamaguchi, Kazumi Hirayama, Michio Tabuchi, Etsuro Mori, and Atsushi Yamadori of Tohoku University Graduate School of Medicine in Sendai, Japan, are working under the umbrella of The Tajiri Project. Their work is helping shed light on the changes that occur in people suffering from various forms of dementia. MRI has been used extensively to study dementia, with a view not only to understanding it, but also to provide the means to provide a definitive diagnosis. However, until now a distinction between brain tissue loss and atrophy due to the "age effect" and the effects of diseases such as Alzheimer's have not laid themselves bare to MRI. Meguro and colleagues hope to remedy this. They selected 485 participants randomly from a community of whom 340 had a Clinical Dementia Rating (CDR) 0 (healthy), 113 were of CDR 0.5 (questionable dementia), and 32 were of CDR 1 and 2 (including 20 with Alzheimer's disease. The researchers visually assessed cortical atrophy, white matter lesions, and other problems. They found that all parts of the brain showed some atrophy in older adults with CDR 0. However, for those of CDR 0.5, the MRI results did not show such a strong correlation between age and dementia. For AD sufferers there was no link at all. Instead, the team observed a strong association with brain tissue atrophy and dementia only in the lateral and medial temporal lobes. For participants of questionable dementia, atrophy of the amygdala, a region of the brain associated with emotions, was the only region correlated with CDR level but they saw no age effect. The researchers conclude that the atrophy of the amygdala or anterior entorhinal is important for diagnosing very mild dementia. "On reading MRI of elderly some findings should be judged carefully," they explain, "Atrophy of the hippocampus, parahippocampal gyrus and amygdala help to distinguish normal aged from AD. Each part of the brain showed atrophy as the age effect, however, as the CDR effect, atrophy was limited to the lateral and medial temporal lobes." The team adds that normal elderly and very mild dementia should be considered distinct. "The amygdala atrophy (anterior entorhinal cortex) is important for discriminating very mild dementia from normal elderly," they add.
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 Meguro and colleagues use MRI to distinguish dementia  MRI can distinguish between dementia and normal brain aging |
