Study On Relationship Between Depression And Cognitive Functions In Parkinson's Disease

Objectives:The purposes of this study were:1. To evaluate the levels and dominating factors of non-motor symptoms ( NMS) of Parkinson's disease.2.To investigate characteristic of cognitive functions of PD patients accomplished with depression.3.To study if event-related potentials(P300)can identify cognitive impairment caused by depression of Parkinson's disease or not.Methods: 1. A total of 86 PD patients from the first affiliated hospital of Soochow University were enrolled into this study from March 2010 to February 2011 .They were assessed by general condition questionnaire,Mini-Mental state Examination,the Revised Hoehn and Yahr Staging Scale (H&Y)and Unified Parkinson Disease Rating Scale(UPDRSⅢand UPDRSIV).2.According to CCMD-3 and Hamilton Depression Rating Scale for Depression-24 items, four groups of subjects participated in the investigation. One group (n=30) included non depressed PD patients (nPD), the second group(n =35) comprised depressed PD patients(dPD), the third group (n=19) consisted of patients with mild or moderate depressive symptoms ,and the fourth group (n=16) comprised patients with major depressive symptoms. All PD patients underwent the following neuropsychological tests: Mini—Mental state Examination ( MMSE ),WAIS-Digit Symbol Substitution Test(WAIS-DSST),WAIS-Digit Span Test(WAIS-DSM),Clock drawing test(CDT),Animal Fluency Test(AFT),Trail Making Test(TMT),Stroop color-word test(CWT)。3. Latency and amplitude of event-related potentials-P300 were analyzed in 65 nPD and dPD patients and in 30 health controls matched for age, sex, and educational level.Results:1.NMS were more common across all stages of PD. Almost all PD patients(98.8%)suffered from NMS with the mean NMSS score at 86.41±45.77.Among these NMS,1evel of mood/cognition was ranked the highest,followed by sleep/fatigue, miscellaneous,attention/memory,urinary symptoms,etc.2. The factors influencing NMS(1)High NMSS score in PD was significantly related with advanced age,rigid-akinetic variant,increased severity of the disease of PD(P<0.05 or P<0.01). Duration of disease,education,medication and general cognitive abilities did not yield significant impact on cognition in PD; Correlation of the NMSS score with UPDRSIV score resulted low(r_S=0.246,P<0.05).(2)Multiple regression analysis:The two variables of the H-Y stage and UPDRSⅢwere eventually included in the multiple regression equation of NMS,explaining 57.8% of the total variance(P<0.01) .3. The pattern of cognitive impairment in Parkinson's disease with depression(1)The two groups(dPD and nPD) did not differ in age, education, gender, disease duration, levodopa equivalent dose and severity of motor symptoms measured by UPDRSⅢand H&Y scale score(P>0.05).(2)Patients of dPD (26.97±1.64)gained lower than nPD(27.73±1.46) in MMSE(F=3.865, P>0.05);There were significant differences in WAIS-DST(total score),WAIS-DSST between dPD and nPD groups(F=6.864～6.879, P<0.05); There were great significant differences in WAIS-DST(backward score),CDT,AFT(total numbers and non-zodiac animal numbers),CWT-C(correct score),SIE(correct score) between dPD and nPD groups(F/t=2.859～10.351,P<0.01); There were also great significant differences in TMT-A(time),TMT-B(time),TMTB-A(time),CWT-C(time),SIE(time) between dPD and nPD groups(F/t=-3.718～10.933 ,P<0.01).(3)On various tests the scores of the PD patients with mild or moderate depressive symptoms were halfway between those of the other two groups of patients .There was a significant difference only in CWT-C(correct score) between PD with mild or moderate depressive symptoms and nPD. There were significant differences in TMTB-A(time),CWT-C(time) and SIE(time) between PD with mild or moderate depressive symptoms and PD with major depressive symptoms groups(P<0.05 or P<0.01).4.Event-related potentials-P300( 1 ) cognitive impairment measured by MMSE was common in PD patients,especially in the depressed PD patients ( P<0.01 ) .Compared with HC group(314.47±18.85, 12.47±3.55),the P3lat was significantly prolonged and the P3amp was significantly lower in nPD group patients(343.80±47.98, 7.37±4.24)(P<0.01 or P<0.001), While compared with HC group,the P3lat was more significantly prolonged and the P3amp was more significantly lower in dPD group patients (373.77±64.39,4.91±3.39) (P<0.001). Compared with nPD group patients , the P3lat was significantly prolonged and the P3amp was significantly lower in dPD group patients(P<0.05).(2)The domains of cognitive functions in PD patients were analyzed for their correlation with P300 latency and amplitude. Correlation of the P300 latency with DSST,CDT,TMT-B(time),SIE(time) resulted low(r=-0.269～0.290,P<0.05),while correlation of the P300 latency with MMSE,WAIS-DST,AFT,SIE(correct score),CWT-C(time),CWT-C(correct score),HAMD resulted moderate(r=-0.523～0.409,P<0.05 or P<0.01). Correlation of the P300 amplitude with CDT,TMT-B(time) resulted low(r=-0.246～0.277,P<0.05), while correlation of the P300 amplitude with MMSE,WAIS-DST,SIE(correct score),CWT-C(time),CWT-C(correct score),HAMD resulted moderate(r=-0.340～0.437,P<0.01).Conclusions:1. NMS are more common across all stages of PD,the domain of mood/cognition(losting interest in surroundings,feeling nervous,lacking motivation) has a great effect upon PD patients . High NMSS score in PD is significantly associated with advanced age,rigid-akinetic variant,increased severity of the disease of PD.2.Depression in PD can influence attention,memory,executive functions,especially executive functions. More severe depressive symptoms , the more obvious cognitive decline.3. The P3lat or P3amp of non-demented PD patients is significantly longer or lower, especially in the depressed PD patients. P300 can be used as a biological marker of screening for the depressioned PD .PD patients reveal a good correlation between P300 and frontal dysfunction.Combination of the two applications may increase the detection rate of cognitive impairment .