| Part I Characteristics of cognitive impairment in patients with vascular cognitive impairment no dementiaBackground Vascular cognitive impairment(VCI) include all levels of cognitive decline resulting from cerebrovascular disease (CVD) or risk factors for CVD, ranging from mild deficits in one or more cognitive domains to a broad dementia-like syndrome. 7Three broad clinical subtypes are included: vascular cognitive impairment no dementia (VCIND), vascular dementia (VD) and mixed dementia (MD). VCI cases that do not meet the criteria for dementia can also be labeled as vascular cognitive impairment no dementia (VCIND). VCI is the most common form of chronic progressive cognitive impairment in the elderly. In the Canadian Study on Health and Aging (CSHA), the prevalence of VCI has been estimated at 5% in people over age 65 years. These included patients with VCIND. The prevalence of VCIND, however, was 2.6%, that of VD was 1.5%. After 5 years, 77 participants (52%) had died and 58 (46%) had developed dementia. The rate of institutionalization among individuals with VCIND is similar to that of those with VD, and the mortality rate of patients with VCIND is similar to that of patients with VD or mixed AD. Meanwhile, several participants showed actual cognitive improvement in the follow-up, indicating that not all patients with VCIND progress to VD definitely. As a preclinical stage of dementia, early diagnosis and intervention have a great signality in the prevention and treatment of dementia.Objective To investigate the characteristics of cognitive impairment in patients with vascular cognitive impairment no dementia.Methods 43 patients with VCIND and 35 age-,sex- and education level matched normal controls were tested with a wide neuropsychological battery of tests covering global cognitive function,memory,attention,visual spatial skills and executive function and the results were compared. These neuropsychological tests include Montreal cognitive assessment(MoCA),auditory verbal learning test(AVLT),digital span test(DST),Rey-Osterrieth complex figure test(CFT),semantic and phonetic fluency tests, digit symbol coding subtest(DSCT),trail making test(TMT),clock drawing test(CDT) and the Stroop color-word test (SCWT).Informed consent was obtained from all participants and the study was approved by the Ethics Committee.Results The cognitive test scores in multiple domains in VCIND group were significantly lower than those of normal control group. The results were as following: MoCA(19.95±2.40 vs 28.09±1.46, F=78.698, P=0.000), AVLT(F=20.157,17.157,10.986,5.063,7.906,all P=0.000), DST(8.05±0.95 vs 11.00±1.42, F=30.030, P=0.000), CFT (31.63±2.44 vs 33.37±1.86, F=3.020, P=0.023), Stroop C(126.47±18.55vs 77.74±7.39, F=53.428, P=0.000), TMT PartA (67.56±4.45vs 62.40±4.78, F=6.606, P=0.000), TMT PartB(278.09±23.13 vs 132.63±22.39, F=197.202, P=0.000), DSCT(17.35±4.36vs 40.66±9.89, F=51.285, P=0.000),semantic fluency test(P=0.000,0.153,0.479,0.004,0.000,0.556), phonetic fluency test(P=0.000,0.651,0.725,0.000,0.002,0.191). The scores of CDT in two groups (22.95±2.84vs 24.83±3.05, F=2.252, P=0.072) were not statistically significant.Conclusions1. Current study indicates that there are cognitive impairment in multiple domains covering memory, attention, executive function and visual spatial skills in patients with VCIND. The overall cognitive impairment is likely to be the result of interactions among all impaired domains.2. Executive function impairment in patients with VCIND may be related to conversion dysfunction,working memory impairment and perceptual motor and information processing speed slowing. The performance in tests of consuming time is a sensitive index reflecting executive dysfunction.3. Memory impairment in patients with VCIND involves the whole process of memory procedure, that is, instant memory, short-time memory and long-term memory are all impaired.Part II Multi-voxel ~1H-magnetic resonance spectroscopy in patients with vascular cognitive impairment no dementiaObjective The metabolic changes in cerebral gray matters in patients with vascular cognitive impairment no dementia (VCIND) were measured by multi-voxel proton magnetic resonance spectroscopy (~1H-MRS) and its relationship to cognitive impairment were investigated. The value of ~1H-MRS in the early diagnosis of VCIND was evaluated.Methods 18 patients and 18 cognitive normal controls were randomly selected from VCIND group and normal control group respectively. With multi-voxel ~1H-MRS, their levels of N-acetyl aspartate(NAA), creatinine (Cr)and choline (Cho) in gray matters of bilateral frontal,temporal,parietal lobes as well as bilateral thalami were detected and the ratios of NAA/Cr, Cho/Cr were compared. Moreover, the correlations between scores of MoCA as well as those of its sub-items and the ratios of NAA/Cr, Cho/Cr were analyzed in VCIND group.Results Compared with control group, the ratios of NAA/Cr were both significantly decreased in gray matters of left(TL) and right thalamus(TR),of which TL 1.56±0.49 vs 1.89±0.48,F=11.22,P<0.01 and TR 1.63±0.45 vs 1.86±0.33,F=5.36,P<0.05. The decreasing degrees of NAA/Cr ratios were positively correlated with the MoCA score(TL:r=0.54, P<0.01;TR : r=0.44,P<0.05), attention (TL:r=0.43, TR :r=0.36, all P<0.05), memory (TL:r=0.61, P<0.01;TR:r=0.49,P<0.05), language(TL:r=0.39, TR :r=0.31, all P<0.05) and visuospatial/executive function (TL:r=0.29, TR :r=0.33, all P<0.05). Conclusions1. Metabolic abnormalities in bilateral thalamic neurons maybe an early and a crucial link in the pathogenesis of overall cognitive impairment in patients with VCIND.2. Multi-voxel 1H-MRS is an important means in the early diagnosis of VCIND.
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