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We appreciate the interest and comments of Drs Harvey, Ron, du Boulay, Murray, and Lewis regarding our recent article in the Archives.The authors commented that the expected rate of signal hyperintensities in younger subjects is greater than O. We agree that this is the case, and suspect that chance sampling variation resulted in a rate of hyperintensities in our control subjects that underestimated the prevalence of these abnormalities in young subjects. However, although greater, the rate reported by Harvey et al is not significantly different from the rate in our control group (Fisher's Exact Test; P<.32). Furthermore, we do not wish to leave readers with the impression that the finding of white matter abnormalities in a sample of bipolar patients is in itself of interest. It is the increased rate of hyperintensities in the bipolar subjects compared with controls that is intriguing. When the rate in
Dupont R, Jernigan TL, Butters N, Delis D, Hesselink JR, Heindel W, Gillin JC. White Matter Abnormalities on Magnetic Resonance Imaging in Bipolar Patients-Reply. Arch Gen Psychiatry. 1990;47(12):1173. doi:10.1001/archpsyc.1990.01810240093017