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Neuroimaging-based brain-age prediction of first-episode schizophrenia and the alteration of brain age after early medication
- Yi-Bin Xi, Xu-Sha Wu, Long-Biao Cui, Li-Jun Bai, Shuo-Qiu Gan, Xiao-Yan Jia, Xuan Li, Yong-Qiang Xu, Xiao-Wei Kang, Fan Guo, Hong Yin
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- Journal:
- The British Journal of Psychiatry / Volume 220 / Issue 6 / June 2022
- Published online by Cambridge University Press:
- 02 December 2021, pp. 339-346
- Print publication:
- June 2022
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- Article
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Background
Neuroimaging- and machine-learning-based brain-age prediction of schizophrenia is well established. However, the diagnostic significance and the effect of early medication on first-episode schizophrenia remains unclear.
AimsTo explore whether predicted brain age can be used as a biomarker for schizophrenia diagnosis, and the relationship between clinical characteristics and brain-predicted age difference (PAD), and the effects of early medication on predicted brain age.
MethodThe predicted model was built on 523 diffusion tensor imaging magnetic resonance imaging scans from healthy controls. First, the brain-PAD of 60 patients with first-episode schizophrenia, 60 healthy controls and 21 follow-up patients from the principal data-set and 40 pairs of individuals in the replication data-set were calculated. Next, the brain-PAD between groups were compared and the correlations between brain-PAD and clinical measurements were analysed.
ResultsThe patients showed a significant increase in brain-PAD compared with healthy controls. After early medication, the brain-PAD of patients decreased significantly compared with baseline (P < 0.001). The fractional anisotropy value of 31/33 white matter tract features, which related to the brain-PAD scores, had significantly statistical differences before and after measurements (P < 0.05, false discovery rate corrected). Correlation analysis showed that the age gap was negatively associated with the positive score on the Positive and Negative Syndrome Scale in the principal data-set (r = −0.326, P = 0.014).
ConclusionsThe brain age of patients with first-episode schizophrenia may be older than their chronological age. Early medication holds promise for improving the patient's brain ageing. Neuroimaging-based brain-age prediction can provide novel insights into the understanding of schizophrenia.
Patterns and processes of latest Ordovician graptolite extinction and recovery based on data from South China
- Chen Xu, Michael J. Melchin, H. David Sheets, Charles E. Mitchell, Fan Jun-Xuan
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- Journal:
- Journal of Paleontology / Volume 79 / Issue 5 / September 2005
- Published online by Cambridge University Press:
- 20 May 2016, pp. 842-861
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We have studied the pattern of graptolite species turnover during the latest Ordovician mass extinction based on four continuous Ashgillian to earliest Llandovery sections together with data from more than 30 other published sections. The studied sections represent relatively shallow-water and deeper-water belts in the Yangtze Platform region. Using temporally scaled range data, species diversities and extinction and origination probabilities have been calculated using several analytical methods, including a capture-mark-recapture method. We test the statistical significance of these results and the apparent taxonomic selectivity of extinction and origination via Monte Carlo simulations and contingency analysis.
Graptolite species diversity within the Yangtze Platform rose steadily during the late Ashgill, until in the mid-late Paraorthograptus pacificus Chron, when rising extinction risk overtook origination. Diversity dropped to very low levels during the early Hirnantian when extinction probabilities attained significantly elevated rates for a period of 600–900 Ky. The period of high extinction risk was followed immediately by a short period of very high origination probability. A second, short period of high extinction risk occurred at the end of Hirnantian time. The Hirnantian extinction events marked a change from relatively low, steady origination and extinction probabilities to a prolonged period of elevated extinction risk and highly variable origination probability that extended well into the Rhuddanian. Extinction and origination was highly selective during the Hirnantian and favored both the survival and diversification of the Normalograptidae relative to the Dicranograptidae, Diplograptidae, and Orthograptidae.
The main phase of extinction in the latest Rawtheyan and early Hirnantian was coincident with continental glaciation in the Southern Hemisphere. The resulting changes in ocean circulation and oxygenation appear to have almost completely eliminated the preferred habitat for most graptolite species. The Yangtze Platform region, however, may have served as a refugium for many taxa that disappeared earlier in other regions as well as a host site for the initiation of graptolite rediversification. Following the end of the glaciation, conditions favorable for graptolite proliferation were restored but graptolite communities remained unstable for much of the late Hirnantian and early Rhuddanian. Accordingly, the Hirnantian mass extinction appears to have fundamentally altered graptolite species dynamics as well as clade dominance patterns. A full understanding of the history of life requires an expanded, hierarchical theory of evolution that gives to mass extinctions (and other levels of selection) an appropriate role in determining clade and diversity histories.