Study On Narcolepsy's Decreased Daytime Alertness And Its Neural Mechanism

Narcolepsy is a kind of chronic neurological diseases with the incidence rate of about three over ten thousand.One of main symptoms of narcolepsy is irresistible sleep attack.Current concept of narcolepsy is defined by semeiology.Its clinical symptoms are excessive daytime sleep,cataplexy(sudden and temporary loss of muscle tone),sleep paralysis,hypnagogic hallucinations.According to the presence of cataplexy,narcolepsy can be divided into two subtypes,type?narcolepsy with cataplexy which is more typical and type?narcolepsy without cataplexy.As the few narcolepsy patients scattered around the world,diagnosis and research on this population becomes really hard.For now,China public,scientific research personnel or even medical workers still know little about this disease.Our study use scales,procedures and PSG to research on alertness of narcolepsy,and then use functional magnetic resonance technology to explore its neural mechanisms.Results are as follows:Study 1 find a daytime alertness function decline phenomenon.We use three kinds of methods to test daytime vigilance: Psychomotor Vigilance Task(PVT),Epworth Sleepiness Scale(ESS)and Multiple Sleep Latency Test(MSLT)which is based on polysomnography equipment.Psychomotor vigilance task(PVT)is used to measure alertness objectively.We see the patient's reaction time is longer than controls,which means patients' psychomotor vigilance is lower.Also,patients got higher scores on Epworth Sleepiness Scale,which means patients' objective vigilance is lower.MSLT results show that patients have shorter sleep latency and abnormal sleep structure.All the three methods show that patients' vigilance level is reduced.It also shows that there's relationship between PVT and MSLT.Firstly,the correlation between PVT,ESS and MSLT was calculated.1/RT was used to represent PVT and REM latency and sleep latency were used to represent MSLT.Negative correlation was found between PVT and MSLT(REM latency)(T=-0.879,p<0.01).We further analyze the regression of PVT to MSLT.Result show that 1/RT significantly project REM latency(F=17.03*,?R2=0.73).According to the results as well as in the previous large-scale network studies in mental and neurological diseases,we further put forward the second hypothesis.Study 2 Default Mode Network and Left Frontal Parietal Network function abnormal in narcolepsy.Also,we use Independent Component Analysis and YEO large-scale brain network template to extract DMN and FPN,then we use two-sample T test to compare the patients and controls on these two brain network.It shows that compared to healthy people,left Angular Gyrus,right Cerebellum Posterior Lobe,Precentral Gyrus,left Superior Temporal Gyrus,left Anterior Cingulate,Medial Frontal Gyrus in narcolepsy patients are in lower activity.The angular gyrus is in higher activity.We further use one-sample T test to see the representativeness of our research samples.Sampling bias is one of the reasons why narcolepsy shows higher activity in IFG.But for angular and IPL,sampling bias is not the reason to explain the difference.The activity of angular is positively correlated with REM latency in narcolepsy(T=0.858,p<0.05).PVT performance and the activity of angular for narcolepsy are in nearly significance(T=-0.731,p=0.062).Brain activity(f ALFF)of Left angular and IPL and right IFG were extracted to correlate with vigilance task results.Angular activity is positively correlated with the sleep latency in MSLT(T=0.858,p<0.05).So we can see the relationship between the decline of DMN activity and the result of MSLT.