RESUMO
Near-infrared spectroscopy (NIRS) studies have reported that prefrontal hemodynamic dysfunction during executive function tasks may be a promising biomarker of psychiatric disorders, because its portability and noninvasiveness allow easy measurements in clinical settings. Here, we investigated the degree to which prefrontal NIRS signals are genetically determined. Using a 52-channel NIRS system, we monitored the oxy-hemoglobin (oxy-Hb) signal changes in 38 adult pairs of right-handed monozygotic (MZ) twins and 13 pairs of same-sex right-handed dizygotic (DZ) twins during a letter version of the verbal fluency task. Heritability was estimated based on a classical twin paradigm using structured equation modeling. Significant genetic influences were estimated in the right dorsolateral prefrontal cortex and left frontal pole. The degrees of heritability were 66% and 75% in the variances, respectively. This implies that the prefrontal hemodynamic dysfunction observed during an executive function task measured by NIRS may be an efficient endophenotype for large-scale imaging genetic studies in psychiatric disorders.
Assuntos
Neuroimagem Funcional/métodos , Genética Comportamental/métodos , Córtex Pré-Frontal/fisiologia , Desempenho Psicomotor/fisiologia , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Comportamento Verbal/fisiologia , Adulto , Algoritmos , Encefalopatias/diagnóstico , Encefalopatias/genética , Encefalopatias/psicologia , Escolaridade , Feminino , Interação Gene-Ambiente , Hemoglobinas/análise , Hemoglobinas/metabolismo , Humanos , Testes de Inteligência , Masculino , Transtornos Mentais/genética , Fatores Socioeconômicos , Gêmeos Dizigóticos , Gêmeos MonozigóticosRESUMO
BACKGROUND: Long-term longitudinal studies are necessary to establish neuroimaging indicators which contribute to the detection of severity changes over time in patients with major depressive disorder (MDD). METHODS: One hundred sixty-five patients with MDD underwent clinical assessments and near-infrared spectroscopy (NIRS) examination at the initial evaluation (T0). After 1.5 years, 45 patients who visited for the follow-up evaluation (T1.5) were included in the analysis. The authors conducted analyses using the 17-item Hamilton Rating Scale for Depression (HAMD) scores and mean oxy-hemoglobin concentration ([oxy-Hb]) changes during a cognitive task in NIRS at T0 (T0_HAMD, T0_[oxy-Hb]) and at T1.5 (T1.5_HAMD, T1.5_[oxy-Hb]), and their intra-individual longitudinal changes (ΔHAMDâ¯=â¯T1.5_HAMDâ¯-â¯T0_HAMD, Δ[oxy-Hb]â¯=â¯T1.5_[oxy-Hb]â¯-â¯T0_[oxy-Hb]). RESULTS: For severity-dependent regions, the Δ[oxy-Hb] in the right inferior frontal gyrus (IFG) was negatively correlated with the ΔHAMD. For severity-independent regions, the intra-class correlation coefficients between T0_ and T1.5_[oxy-Hb] were moderate in the bilateral middle frontal gyri (MFG). LIMITATIONS: The percentage of patients included in the follow-up examination was relatively small. CONCLUSIONS: Brain activation in the right IFG and the bilateral MFG as measured by NIRS may differentially indicate clinical severity and trait-related abnormalities in MDD.