Investigation Of Intertemporal Decision-making Function And Its Correlation With Impulsive Personality Characteristics Of Geriatric Depressive Patients

Objective: In daily life,people often need to weigh and make trade-offs between different time points,especially now and in the future,such as a smaller immediate reward and a larger delayed reward,which is called intertemporal decision making.The delay discounting task is a widely used paradigm for exploring the intertemporal decision and measuring impulsive choice,which refers to individual’s subjective value of reward decreased gradually with the delay time of reward obtained increased.For example,a choice between 50 yuan immediately received and 100 yuan to be received after a week may be treated as comparable to a choice between an immediate 50 yuan and,say,an immediate 25 yuan.Impulsivity is widely described as a rapid and unplanned response to internal or external stimuli without considering the negative consequences of these reactions on individuals or others.Impulsivity is a multi-dimensional structure and a variety of measures to assess impulsive behavior have been developed,including self report personality measurement and external behavior tasks which are associated with a particular structure of impulse.The results about the correlation of delayed discounting and self reporting impulsivity are different.Geriatric depression can be divided into two subtypes: early onset and late onset.These two subtypes may have distinct etiologies in which late onset geriatric depression is more associated with cardiovascular burden and early onset geriatric depression with genetic predisposition.There are few studies on delayed discounting in geriatric depression abroad,and the subtypes of geriatric depression has not been discussed.In clinical studies,geriatric depression generally refers to the first onset of primary depression in the elderly.This study explored the intertemporal decision-making function and its correlation with impulsive personality characteristics of geriatric depressive patients.Methods: 40 Patients with geriatric depression(GD)and 40 demographic characteristic matched health controls(HC)were recruited.Both the decision-making function,impulsive triats and cognitive function of the subjects were measured through the delay discounting task,the Barratt impulsiveness scale and Mini-Mental State Examimation(MMSE)separately.In addition,the degree of depression in geriatric depressive patients were evaluated by Hamilton Depression Scale(HAMD).Results: The lgk,a logarithm of the delay discounting rate k,and the scores of Barratt Impulsiveness Scale,Attentional Impulsiveness Subscale,Motor Impulsiveness Subscale in GD group [(-2.00±0.81),(42.67±8.51),(46.50±16.84),(43.50±10.45)] were larger than these of the HC group [(-2.31±0.51),(32.27±6.18),(34.81±8.15),(26.88±7.65],and the differences were statistically significant(t=2.060,P=0.043;t=6.252,P<0.001;t=3.951,P<0.001;t=8.117,P<0.001).In addition,lgk showed a positive correlation with the scores of Motor Impulsiveness Subscale(r=0.408,p=0.009),which showed no correlation with the total scores of the Barratt Impulsivity Scale(r=0.204,P=0.207)and the scores of Attentional Impulsiveness Subscale(r=0.000,P=0.998)in GD group.Conclusion: The delayed discounting ability of geriatric depression is impaired compared with the healthy controls and is correlated with the scores of Motor Impulsiveness Subscale,suggesting that in the negative emotional state,delayed discounting and Motor Impulsiveness Subscale may measure the same field of impulsivity.This study provides a theoretical basis for assessing the health of the patients,the changes in the outcome of the treatment and the improvement of their daily functions in clinical works.