No abstract

Patients diagnosed with mild cognitive impairment (MCI) have a higher risk of developing Alzheimer's disease (AD). However, not all such patients develop this kind of dementia. The purpose of this prospective study was to assess whether regional cerebral blood flow (rCBF) patterns measured with technetium-99m ethyl cysteinate dimer single-photon emission tomography ((99m)Tc-ECD SPET) in patients suffering from MCI are useful in predicting progression to AD. The study group comprised 42 patients who fulfilled MCI criteria according to the International Psychogeriatric Association and the Alzheimer's Disease Cooperative Study. rCBF was calculated in 16 regions of interest (ROIs). All patients were clinically assessed for 1-3 years. Twenty-one developed AD (group I) while the initial diagnosis of MCI was retained in the other 21 (group II). ROC curves were designed, and sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios were determined for each ROI. Compared with group II (MCI), group I (AD) showed a significant reduction of relative blood flow (RBF), ranging from 7% to 10%, in the following areas: right and left prefrontal, right and left frontal, right and left parietal, right and left temporal, right and left frontoparietotemporal and left posterior lateral temporal. Left prefrontal, left frontal and left parietal areas showed sensitivities and specificities higher than 75% and areas below the ROC curve close to 80%. This study shows that RBF patterns in the right and left prefrontal, right and left frontal and left parietal areas are sensitive early markers of progression towards AD. Reduction of rCBF in the medial temporal and anterior lateral temporal cortex has no value as a predictor since it also occurs in patients with MCI who remain stable.

To find early clinical markers that may predict a likely progression to Alzheimer's disease (AD), the authors performed neuropsychological tests on 82 mild cognitive impairment (MCI) subjects. After 3 years, 38 patients developed AD while 44 retained the diagnosis of MCI. The cognitive differences between the groups were studied. Patients who developed AD showed significantly lower values than did MCI subjects in some neuropsychological scores (P = .02-.001), with sensitivities and specificities higher than 84% and 64%, respectively, for detecting early-onset AD, with a 7.9-fold increased risk of converting to AD (P < .001). Regarding the logistic regression model, the CAMCOG Memory and Perception cognitive screening items were the optimum independent tools to classify the patients who will progress to AD, showing a relative risk of progression of 10.5 (P = .002), 5.5 (P = .008), and 3.9 times (P = .05), respectively, with a sensibility of of 92.1% and a specificity 72.7%.

The main goal of the present study was to explore whether regional cerebral blood flow (rCBF) differs between obsessive-compulsive disorder (OCD) patients without chronic motor tic disorder and those OCD patients with a comorbid chronic tic disorder. Twenty-seven patients suffering from OCD (DSM-IV criteria), including 7 OCD patients who met DSM-IV criteria for simple chronic motor dic disorder, and 16 healthy volunteers were examined at rest using a high resolution SPECT. Seven regions of interest (ROIs) were manually traced and quantified as a percentage of the mean cerebellar uptake. Severity of obsessive-compulsive symptoms (OCS), anxiety and depressive symptoms and presence of motor tics were assessed with the Y-BOCS, HRS-A, HRS-D, MADRS, and Yale Global Tics Severity Scale, respectively. We found a significant relative decrease in rCBF in OCD patients without motor tics compared to healthy volunteers in the right orbitofrontal cortex (OCD without tics = 0.87; healthy volunteers = 0.94; p = 0.02). No significant differences in rCBF were seen when OCD patients with and without chronic tics were directly compared. A lower severity of OCS in OCD patients with chronic tics was found. These results are consistent with previous functional neuroimaging studies at rest that have widely involved the orbitofrontal cortex in the pathophysiology of the OCD. However, our results do not support the idea that OCD patients with chronic tics may constitute a biological subgroup within the OCD.

The combination of functional imaging and neuropsychological tests can diagnose with high sensitivity and specificity if a patient is suffering cognitive impairment in its early stages, and may aid in predicting the risk of developing dementia.