Are conceptual abilities impaired in schizophrenia?

Whereas semantic processing deficits are well-documented in schizophrenia, conceptual abilities have been poorly explored. This study aims at specifically exploring conceptualization abilities in 34 adults fulfilling schizophrenia according to DSM-IV and 34 healthy controls with similar socio-demographic characteristics. The 2 groups were assessed on the WAIS-R similarities test and the concept generation test (Raoux et al., 2014) consisting of free-sorting 6 cards of pictures of animals and geometric shapes to be separated in two groups or categories based on common attributes. After each sorting, the participant is asked to explain his/her sorting. Whereas the schizophrenic patients performed significantly poorer than the control participants in the semantic knowledge and lexico-semantic tests, there was no difference neither in the WAIS-R similarities test nor in the concept generation test, which supports the hypothesis of preserved high level conceptualization abilities in schizophrenia. However, qualitative differences in performing the concept generation test were evidenced. The patients used more often mixed criteria leading them to compare two different hierarchical levels (e.g., low-level physical attributes vs. high-level semantic criteria). Furthermore, the qualitative analysis based on the explanations provided by the participants shows that the categorizations achieved by schizophrenic patients are more often based on unexpected criteria.

[An alternative word-list for the Free and cued selective reminding test (FCSRT): list presentation and reliability study]. / Validation d'une troisième liste de mots pour l'épreuve Rappel libre/Rappel indicé à 16 items (RL/RI-16) : présentation de la liste C et étude de fidélité

The Free and cued selective reminding test (FCSRT) is one of the most effective neuropsychological test used to assess verbal memory in elderly people with memory problems. There are currently two lists of words: the initial French version (list A) and an alternative one (list B). However, diagnosing early Alzheimer's disease in memory clinics often requires more than two evaluations, particularly in patients with very mild cognitive symptoms and patients with young onset disease. Usually, memory tests can be affected by practice effect, so several expositions of the same list of words could limit its clinical utility. The aim of our study was to create and validate a second alternative version (list C). The study sample was composed of 222 healthy volunteers aged from 17 to 84 years with a mean age of 44.6 years of whom 57% were females and 71% had a higher education. Within a two-month interval, each subject performed the test with one word-list and then the second one. The order of lists presentation was counterbalanced. Our findings indicate that the new alternative list (list C) is equivalent to the initial list of word (list A) for all the recall and recognition subscores, except the number of intrusive errors. This new list of words should be helpful to minimise potential practice effect and better assess memory decline in situations where the FCSRT has to be repeated across follow-up.

Gender-related differences in visuospatial memory persist in Alzheimer's disease.

Gender differences in visuospatial cognition favoring men are larger in tasks requiring active information manipulation than in tasks requiring passive storage. This study was designed to determine whether male advantage in active manipulation of visuospatial information can still be evidenced in Alzheimer's disease (AD). Twenty male and 20 female AD patients with equivalent age, education, dementia severity (Mini-Mental State Examination and Mattis Dementia Rating Scale), and visual discrimination abilities were recruited. We administered the forward span of Corsi block-tapping task and Vecchi's matrix memory task involving passive temporary retention of stimuli location. Active manipulation of visuospatial information was assessed with the backward span of Corsi block-tapping task and Vecchi's pathway task in which patients were required to mentally generate a pathway within a matrix. The results showed that scores on the tasks involving passive storage of visuospatial information were equivalent between the two groups of patients, whereas men performed significantly better than women in tasks requiring active manipulation of visuospatial information. This result was limited to visuospatial processing since no difference between male and female patients was evidenced in the verbal short-term memory tasks, neither when the task involved passive storage nor when the task required active processing. Therefore, this study suggests that, besides other variables such as education or lifestyle factors, gender might also modulate the cognitive manifestation of AD.

Cognitive impairment improves the predictive validity of the phenotype of frailty for adverse health outcomes: the three-city study.

OBJECTIVES: To determine whether adding cognitive impairment to frailty improves its predictive validity for adverse health outcomes. DESIGN: Four-year longitudinal study. SETTING: The French Three-City Study. PARTICIPANTS: Six thousand thirty community-dwelling persons aged 65 to 95. MEASUREMENTS: Frailty was defined as having at least three of the following criteria: weight loss, weakness, exhaustion, slowness, and low physical activity. Subjects meeting one or two criteria were prefrail and those meeting none as nonfrail. The lowest quartile in the Mini-Mental State Examination (MMSE) and the Isaacs Set Test (IST) was used to identify subjects with cognitive impairment. The predictive validity of frailty for incident disability, hospitalization, dementia, and death was calculated first for frailty subgroups and then rerun after stratification according to the presence or absence of cognitive impairment. RESULTS: Four hundred twenty-one individuals (7%) met frailty criteria. Cognitive impairment was present in 10%, 12%, and 22% of the nonfrail, prefrail, and frail subjects, respectively. Those classified as frail scored lower on the MMSE and IST than those classified as prefrail and nonfrail. After adjustment, frail persons with cognitive impairment were significantly more likely to develop disability in activities of daily living (ADLs) and instrumental ADLs over the following 4 years. The risk of incident mobility disability and hospitalization was marginally greater. Incident dementia was greater in the groups with cognitive impairment irrespective of their frailty status. Conversely, frailty was not a significant predictor of mortality. CONCLUSION: Cognitive impairment improves the predictive validity of the operational definition of frailty, because it increases the risk of adverse health outcomes in this particular subgroup of the elderly population.

Clustering and switching processes in semantic verbal fluency in the course of Alzheimer's disease subjects: results from the PAQUID longitudinal study.

Reduced semantic fluency performances have been reported in the preclinical phase of Alzheimer's disease (AD). To investigate the cognitive processes underlying this early deficit, this study analyzed the verbal production of predemented subjects for the animals category with the qualitative parameters related to clustering (i.e. the ability to generate words belonging to semantic subcategories of animals) and switching (i.e. the ability to shift from one subcategory to another) proposed by Troyer. This qualitative analysis was applied to the PAQUID (Personnes Agées QUID) cohort, a 17-year longitudinal population-based study. The performances on the animal verbal fluency task of 51 incident cases of possible and probable AD were analyzed at the onset of dementia, 2 years and 5 years before dementia onset. Each case was matched for age, sex and education to two control subjects leading to a sample of 153 subjects. The mean cluster size and the raw number of switches were compared in the two samples. The results revealed a significantly lower switching index in the future AD subjects than in the elderly controls including 5 years before dementia incidence. A significant decline in this parameter was evidenced all along the prodromal phase until the clinical diagnosis of dementia. In contrast, the mean cluster size could not discriminate the two groups. Therefore the results support the hypothesis that impaired shifting abilities - rather than semantic memory storage degradation - could explain the early decline in semantic fluency performance occurring in the predementia phase of AD.

Executive functions deficit in mild cognitive impairment.

OBJECTIVE: To investigate whether patients diagnosed with amnestic mild cognitive impairment (MCI) have also impairment in attention/executive functions, and therefore to clarify whether all subcomponents of executive control are equally affected in MCI. BACKGROUND: MCI refers to the transitional state between normal aging and dementia. Amnestic MCI is characterized by impaired episodic memory, although subtle impairment of executive functions has been noted on neuropsychologic tests. METHODS: We investigated 20 MCI patients and 20 normal controls using episodic memory, attention/executive functions, language, and praxis tests. RESULTS: MCI patients had significantly lower scores on all measures of the Free and Cued Selective Reminding Test (P<0.05 to 0.01) than controls. Furthermore, MCI had a greater number of perseverations (P<0.01) on Modified Card Sorting Test and the lowest performance on the Stroop Test (P<0.02). CONCLUSIONS: Our findings showed impairment in episodic memory performance in MCI as compared with that of controls. In addition, MCI patients had problems with response inhibition, switching, and cognitive flexibility, which encompass various aspects of executive functions. This suggests that MCI may be identified by using a more detailed procedure for the assessment of cognitive decline than the evaluation of memory alone.

Diffusion tensor imaging in early Alzheimer's disease.

Our aim was to investigate the extent of white matter tissue damage in patients with early Alzheimer disease (AD) using diffusion tensor magnetic resonance imaging (DTI). Although AD pathology mainly affects cortical grey matter, previous magnetic resonance imaging (MRI) studies showed that changes also exist in the white matter (WM). However, the nature of AD-associated WM damage is still unclear. Conventional and DTI examinations (b=1000 s/mm(2), 25 directions) were obtained from 12 patients with early AD (Mini Mental State Examination [MMSE] score=27, Grober and Buschke test score=33.2, digit span score=5.6) and 12 sex- and age-matched volunteers. The right and left mean diffusivity (MD) and fractional anisotropy (FA) of several WM regions were pooled in each patient and control, and compared between the two groups. Volumes of the whole brain and degree of atrophy of the temporal lobe were compared between the two groups. In AD, MD was increased in the splenium of the corpus callosum and in the WM in the frontal and parietal lobes. FA was bilaterally decreased in the WM of the temporal lobe, the frontal lobe and the splenium compared with corresponding regions in controls. Values in other areas (occipital area, superior temporal area, cingulum, internal capsule, and genu of the corpus callosum) were not different between patients and controls. No correlations were found between the MMSE score and the anisotropy indices. Findings of DTI reveal abnormalities in the frontal and temporal WM in early AD patients. These changes are compatible with early temporal-to-frontal disconnections.

A longitudinal study of quantitative and qualitative features of category verbal fluency in incident Alzheimer's disease subjects: results from the PAQUID study.

Category fluency tests were administered at baseline and after 3 and 5 years on two subgroups of subjects from a population-based cohort of elderly subjects: 52 cases of incident possible and probable Alzheimer's disease (AD) and 104 age- and education-matched subjects who remained nondemented. Quantitative and qualitative features of category fluency were assessed to determine how changes occur within 5 years of the diagnosis of AD. Consistent with previous results, we found that the number of words produced on this task was already significantly lower 5 years before the diagnosis in subjects with incident AD as compared with subjects who did not become demented. However, the rate of repetitions only significantly increased in AD subjects at the time of diagnosis, and the rate of intrusions remained low and not significantly different between the two groups. Thus, it is concluded that dysfunction in cognitive processes underlying repetitions and intrusions in verbal fluency tasks, such as inhibitory processes and working memory, may not be the main cause of the very early deficit in verbal fluency occurring in AD.

Patterns of memory impairment and perseverative behavior discriminate early Alzheimer's disease from subcortical vascular dementia.

Previous research suggests that the neuropsychological deficits in Alzheimer's disease (AD) are different from that of vascular dementia (VaD), especially with respect to memory, language and executive functions, but negative findings were reported. Our objective was to clarify the cognitive syndrome in AD and VaD in the early stage of these disorders. We investigated 45 patients with early AD, 23 patients with subcortical VaD and 35 normal controls. All subjects were assessed with neuropsychological battery designed to measure memory, language, praxis and executive functions. Patients with AD had significantly worse scores on Story Recall (p<0.02) and on all measures of the Free and Cued Selective Reminding Test (p<0.03 to 0.001) than did patients with VaD, as well as greater number of perseverations (p<0.02) on category fluency. Conversely, VaD patients had more perseverations (p<0.02) on the Modified Card Sorting Test. Despite the similar degree of overall cognitive deterioration, the findings show more impaired retrieval from long-term storage in AD than in VaD. Moreover, the data suggest that AD and subcortical VaD affect perseverative behavior in a different fashion. These results may be helpful in differentiating AD from VaD in the early stage of these disorders, when mental impairments are not pervasive yet.