A longitudinal follow-up of 550 mild cognitive impairment patients: evidence for large conversion to dementia rates and detection of major risk factors involved

The most recent studies about mild cognitive impairment (MCI) are focused on the search for factors that make patients more vulnerable to conversion to dementia, mainly Alzheimer's disease (AD). The aim of this study was to determine which neuropsychological test performances, including episodic memory profiles, and genetic risk factors (APOE ε4) better predict early conversion to dementia among the four MCI subtypes. Data from 550 MCI patients were analyzed for the purpose of this study and were classified according to Petersen's criteria (2004), and also taking into account the absence (probable MCI) or presence (possible MCI) of comorbidities that could explain cognitive deficits. MCI cases were divided into Probable amnestic (Pr-aMCI) (n = 115), probable non-amnestic (Pr-naMCI) (n = 37), possible amnestic (Pss-aMCI) (n = 234), and possible non-amnestic (Pss-naMCI) (n = 164), single or multiple domain. In the whole MCI sample, regression analysis showed that low performances on Orientation, Verbal Delayed Recall of the Word List Learning test from WMS-III, and Luria's Clock test were associated with conversion to dementia, independently of APOE ε4 allele. Cox proportional-hazards showed that the Probable MCI subtype, presence of storage memory impairment, multiple domain condition, and presence of at least one ε4 allele increased the risk of conversion to dementia. Multivariate survival and Kapplan-Meier analyses showed that the Pr-aMCI with storage memory impairment had the most and closest risk of conversion to dementia. In conclusion, the Pr-aMCI subset of patients had 8.5 times more risk of converting to dementia than the Pss-naMCI group, who displayed the slowest conversion rate to dementia.

Cut-off scores of a brief neuropsychological battery (NBACE) for Spanish individual adults older than 44 years old

The neuropsychological battery used in Fundació ACE (NBACE) is a relatively brief, and easy to administer, test battery that was designed to detect cognitive impairment in the adulthood. The NBACE includes measures of cognitive information processing speed, orientation, attention, verbal learning and memory, language, visuoperception, praxis and executive functions. The aim of the present study was to establish the cut-off scores for impairment for different levels of age and education that could be useful in the cognitive assessment of Spanish subjects who are at risk for cognitive impairment, especially dementia. Data from 1018 patients with a mild dementia syndrome, and 512 cognitively healthy subjects, older than 44 years, from the Memory Clinic of Fundació ACE (Barcelona, Spain) were analyzed. In the whole sample, cut-off scores and sensitivity/specificity values were calculated for six conditions after combining 3 age ranges (44 to 64; 65 to 74; and older than 74 years old) by 2 educational levels (until Elementary school; and more than Elementary school). Moreover, general cut-offs are reported for Catalan and Spanish speakers. The results showed that most of NBACE tests reached good sensitivity and specificity values, except for Ideomotor praxis, Repetition and Verbal Comprehension tests, which had a ceiling effect. Word List Learning from the Wechsler Memory Scale-III and Semantic Verbal Fluency were the most useful tests to discriminate between cognitively healthy and demented subjects. The NBACE has been shown to be a useful tool able to detect cognitive impairment, especially dementia, in older than 44 years Spanish persons.

A two-year follow-up of cognitive deficits and brain perfusion in mild cognitive impairment and mild Alzheimer's disease

The 15-Objects Test (15-OT) provides useful gradation of visuoperceptual impairment from normal aging through Alzheimer's disease (AD) and correlates with temporo-parietal perfusion. The objectives of this study were to analyze progression of 15-OT performance in mild cognitive impairment (MCI) and AD, and its correlates with cognition and single photon emission computerized tomography (SPECT), as well as to examine neuropsychological and SPECT differences between the MCI patients who developed AD and those who did not. From the initial 126 participants (42/group), 38 AD, 39 MCI, and 38 elderly controls (EC) were reassessed (SPECT: 35 AD, 33 MCI, 35 EC) after two years. The progression of cognitive and SPECT scores during this period was compared between groups, and baseline data between converters and non-converters. The 15-OT was the only measure of progression that differed between the three groups; worsening scores on 15-OT were associated with worsening in verbal and visual retention, and decreased perfusion on left postsubicular area. In the MCI patients, cerebral perfusion fell over the two years in medial-posterior cingulate and fronto-temporo-parietal regions; AD showed extensive changes involving almost all cerebral regions. No SPECT changes were detected in controls. At baseline, the MCI patients who developed AD differed from non-converters in verbal recognition memory, but not in SPECT perfusion. In conclusion, SPECT and 15-OT appear to provide a potential measure to differentiate between normal aging, MCI, and AD. Worsening on 15-OT was related to decreased perfusion in postsubicular area; but further longitudinal studies are needed to determine the contribution of 15-OT as a predictor of AD from MCI.

Normative data of a brief neuropsychological battery for Spanish individuals older than 49

There is an increasing need for standardized assessment of cognition in older patients that is relatively brief, easy to administer, and has normative data adjusted for age and educational attainment. We tested 332 literate, cognitively normal, Spanish persons older than 49 years from the Memory Clinic of Fundació ACE, Institut Català de Neurociències Aplicades (Barcelona, Spain) with measures of cognitive information processing speed, orientation, attention, verbal learning and memory, language, visuoperception, praxis, and executive functions. Several of the tests were affected by age, education, and/or gender, but the language of administration (i.e., Spanish or Catalan) did not affect the test scores. Standardized scores and percentile ranks were calculated for each age and/or education group for use by clinical neuropsychologists.

Brain perfusion correlates of visuoperceptual deficits in mild cognitive impairment and mild Alzheimer's disease

Visuoperceptual processing is impaired early in the clinical course of Alzheimer's disease (AD). The 15-Objects Test (15-OT) detects such subtle performance deficits in mild cognitive impairment (MCI) and mild AD. Reduced brain perfusion in the temporal, parietal, and prefrontal regions have been found in early AD and MCI patients. The objectives of this study were to confirm the role of the 15-OT in the diagnosis of MCI and AD and to investigate the brain perfusion correlates of visuoperceptual dysfunction (15-OT) in subjects with MCI, AD, and normal aging. Forty-two AD, 42 MCI, and 42 healthy elderly control subjects underwent a brain Single Photon Emission Tomography (SPECT) and separately completed the 15-OT. An analysis of variance compared 15-OT scores between groups. SPM5 was used to analyse the SPECT data. 15-OT performance was impaired in the MCI and AD patients. In terms of the SPECT scans, AD patients showed reduced perfusion in temporal-parietal regions, while the MCI subjects had decreased perfusion in the middle and posterior cingulate. When MCI and AD groups were compared, a significant brain perfusion reduction was found in temporo-parietal regions. In the whole sample, 15-OT performance was significantly correlated with the clinical dementia rating scores, and with the perfusion in the bilateral posterior cingulate and the right temporal pole, with no significant correlation in each separate group. Our findings suggest that the 15-OT performance provides a useful gradation of impairment from normal aging to AD, and it seems to be related to perfusion in the bilateral posterior cingulate and the right temporal pole.

Detection of visuoperceptual deficits in preclinical and mild Alzheimer's disease

Exhaustive neuropsychological assessment of mild cognitive impairment (MCI) subjects frequently identifies cognitive deficits other than memory. However, visuoperception has rarely been investigated in MCI. The 15-Objects Test (15-OT), a visual discrimination task based on the Poppelreuter Test, consists of 15 overlapping objects. Poppelreuter-type tests are frequently used to detect visual agnosia. However, more complex tests, such as the 15-OT, are required to detect visuoperceptual signs in those patients who perform correctly on simple tests. The aim of the present study was to investigate visuoperceptual deficits in MCI patients and to assess the usefulness of the 15-OT to discriminate Alzheimer's disease (AD) and MCI patients from controls. The 15-OT, and a neuropsychological battery included in the diagnostic assessment, was administered to 44 healthy controls, 44 MCI patients, and 44 mild AD patients. Performance on the 15-OT was significantly different between groups. MCI scored between AD and controls. When MCI and AD patients had relatively normal performance on simple tests (Poppelreuter), increased significant abnormalities were found by a more difficult visuoperceptual test (15-OT). Regression analyses showed that the 15-OT was a significant predictor of group membership, but the Poppelreuter Test did not significantly contribute to the models. Visuoperceptual processing is impaired early in the clinical course of AD. The 15-OT allows detection of visuoperceptual deficits in the preclinical and mild AD stages, when classical tests are still unable to detect subtle deficits. So, its inclusion in neuropsychological batteries that are nowadays used in the clinical practice would allow increasing their diagnostic potential.