A Discussion In The Relationship Between Leukoaraiosis And Cognitive Impariment

Cognition is a basic human activity, refers to awareness and understanding of the psychological process of things. Vascular cognitive impairment(VCI) is defined as various types and degree of cognitive impairment leaded by or associated with vascular factors,and is one of the highest incidence of cognitive impariment in clinical.VCI is Divided into non-vascular dementia cognitive impairment (V-CIND) and vascular dementia (VaD) Which is divided into seven subtypes, subcortical ischemic vascular dementia (SIVD) is the most common clinical subtype. Leukoaraiosis (LA) as a cause of subcortical ischemia and the relationship between cognitive impariment has caused a broad view of the scholars.Leukoaraiosis (LA) was first proposed by Hachinski in 1987 , it is a video of academic language used to describe the periventricular and semi-oval center of symmetry diffuse white matter punctate or patchy changes. CT showed low-density zone, MRI T1-weighted images showed low signal,MRI T2-weighted images showed high signal. Many brain diseases are associated with the existence of LA.With the widespread use of head CT and MRI imaging methods in brain disease,the detection rate of LA is significantly increased.The relationship between LA and cognitive impariment is one of the issue of great importance. Domestic and foreign research results on the LA's role in cognitive impariment remains controversial. Most of the studies regards that LA is closely related with impaired cognitive function. However, some studies suggest that there is no correlation between cognitive impairment and LA. This study is to explore the relationship between LA and cognitive impariment.This study select the inpatients whose head CT examination proved to be LA over the age of 60 in department of neurology of The Second Hospital Of Jilin University from March to December 2008.With the LA classification grading standards we divided them into LA-1 group, LA-2 group, LA-3 group and LA-4 group. LA group selected a total of 67 cases of patients, age(71.62±4.64)years; 38 male, 29 female. After grading, 12 patients in LA-1 group,20 patients in LA-2,21 patients in LA-3 group,14 patients in LA-4 group. The socio-demographic data was not significant in each group.The cognitive function was quantified, we used the scale of the mini-mental state examination(MMSE),the Montreal Cognitive Function Assessment Scale(MoCA), activities of daily living scale (ADL). Hachinski Ischemic Scale used to determine VCI or others. We diagnosis VaD According to DSM-Ⅳdiagnostic criteria.We analysis the characteristics of cognitive impairment according to MoCA Scale.The results showed,the cases were all older patients with multiple vascular risk factors.The prevalence rate of VCI in LA cases is 85.07%,V-CIND is 23.88%,VaD is 61.19%.In LA-3, LA-4 group, the prevalence rate of VCI is as high as 95.24% and 100%.In LA group,the composition of normal intelligence, V-CIND and VaD are different,with the LA increased, the intelligence Scale MoCA, MMSE scores decreased, ADL scores increased gradually,and there was a significant difference between each group. Scale MoCA analysis showed that there was a significant anomaly in the implementation of visual spatial ability, attention and concentration, abstract thinking ability, delayed recall ability, directional power in LA patients,the above-mentioned areas of cognitive scores decreased with the rise of LA level.LA often occur in the elderly, vascular factors are the main risk factors, the main pathogenesis is demyelination and ischemia. LA lesions mainly located in deep periventricular white matter which is vulnerable to the ischemia based on the anatomical and physiological characteristics. Hypertensive cerebral arteriosclerosis is the basis of white matter ischemia.From functional anatomical point of view, the main effect of white matter is the connectivity role,linking the cortex, subcortical gray matter, forming a complete system. LA lesions destroyed this linking and lead to incompletinon of the cortex and subcortical gray matter function. Limbic system as the basis of anatomical structure of human advanced function-intelligence, which fibers are through the periventricular white matter, forming a complete intelligent system, LA is bound to damage to the limbic system fiber linking, cause the damage of the limbic system, thus giving rise to human cognitive impariment.The limbic system is composed of of the Papez loop around thalamus and Livengston loop around the midvrain. Papez loop, also known as the inner edge of ring, each once on lift and right, was linked by the hippocampus. The nerve impulses is afferented from the septal area into cingulate, and then to the hippocampus, and then by the hippocampus, fornix afferented to papillary body. The impulse then afferented into the former nuclear beam via the hypothalamus. By the hypothalamus which in turn rebate back to the previous Chuan radiation. There is extensive contacts between Cingulate cortex and the new cortex. Hippocampus which is a place to memory and storage, the damage will be serious in recent memory loss. Livengston edge loop, also known as Basolateral loop, including the orbital frontal surface, anterior temporal lobe, insula, septal area, amygdala and dorsomedial hypothalamus nuclear. This ring is related with memory and emotions, and in which the amygdala is the emotional expression, and the Central and lateral temporal lobe damage can lead to refractory forgetfulness.Deep white matter lesions may damage the frontal-subcortical loop, causing frontal-subcortical loop dysfunction ,adn then leading the implementation damage outstanding such as abstract thinking, concept formation and conversion,information processing speed, the interference suppression function,thus giving rise to the impariment of abstract thinking ability, implementation ability, attention and other areas of cognitive impariment. At the same time, deep brain white matter lesions also damaged the joint associaton fiber(callosal convolution,superior longitudinal fasciculus, fasciculus fronto- occipitalis), which play an important role in the conduction of cognitive and emotional . Due to extensive white matter lesions priority damage joint fibers,lead the impariment of frontal lobe . Memory damage is common in VCI .And the reasons may be that vascular lesions damage the hippocampus and memory-related medial temporal lobe; or the shrinkage of the hippocampus and cortex.with the vascular lesions.In a word, this study suggest, there is correlation between LA and cognitive impariment.LA can cause varying degrees of cognitive impairment. The more serious LA is, the more obvious cognitive impariment is and the incidence of VCI.It is abnormal in the implementation of visual spatial ability, attention and concentration, abstract thinking ability, delayed recall ability with LA cognitive impariment. With the rise of the LA classification, there is significant differences in the above areas. Clinicians should pay attention to the above-mentioned cognitive test domain.