Deciphering logopenic primary progressive aphasia: a clinical, imaging and biomarker investigation.

Within primary progressive aphasia the logopenic variant remains less understood than the two other main variants, namely semantic and non-fluent progressive aphasia. This may be because of the relatively small number of explored patients and because of the lack of investigations with a comprehensive three-level characterization of cognitive, brain localization and biological aspects. The aim of the present study was to decipher the logopenic variant through a multimodal approach with a large cohort of 19 patients (age 66.5 ± 8.7 years, symptom duration 3.2 ± 0.6 years) using detailed cognitive and linguistic assessments, magnetic resonance imaging and perfusion single-photon emission computed tomography as well as cerebrospinal fluid biomarkers screening for Alzheimer pathology. The linguistic assessment unveiled that language dysfunction is not limited to the typical feature of word finding and verbal working memory impairments but that it extends into the language system affecting to some degree syntactic production, phonological encoding and semantic representations. Perfusion tomography revealed damage of the temporal-parietal junction with a peak of significance in the superior temporal gyrus (Brodmann area 42), and of some less significant prefrontal areas (Brodmann areas 8, 9 and 46), whereas hippocampal cortices were unaffected. Magnetic resonance imaging, which was visually assessed in a larger group of 54 patients with logopenic, non-fluent, semantic variants as well as with posterior cortical atrophy, confirmed that the logopenic variant demonstrates predominant atrophy of left temporal-parietal junction, but that this atrophy pattern has a relatively poor sensitivity and specificity for clinical diagnosis. Finally, the biomarker study revealed that two-thirds of the logopenic patients demonstrated a profile indicative of Alzheimer pathology whereas one-third had a non-Alzheimer profile. Splitting the two groups showed that logopenic aphasia due to probable Alzheimer pathology is a more aggressive variant characterized by more extensive language/cognitive disorders affecting, in addition to lexical processes and verbal working memory, also phoneme sequencing, semantic processing and ideomotor praxis. Concordantly, logopenic aphasia due to probable Alzheimer pathology demonstrated more extensive brain hypoperfusion involving larger regions throughout the inferior parietal, the posterior-superior and the middle temporal cortex. These findings allow for unfolding logopenic aphasia into two subvariants differing by disease severity, lesion nature and lesion distribution, which has important implications for diagnosis, patient management and for potential future trials with anti-Alzheimer drugs. The present data therefore provide novel insight into the cognition and brain damage of logopenic patients while unveiling the existence of distinct diseases constituting a 'logopenic aphasia complex'.

Trajectory Pattern of Cognitive Decline in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy.

BACKGROUND AND OBJECTIVE: The course and pattern of cognitive decline in ischemic cerebral small vessel disease (cSVD) remains poorly characterized. We analysed the trajectory pattern of cognitive decline from age 25 to 75 years in CADASIL. METHODS: We applied latent process mixed models to data obtained from CADASIL patients who were repeatedly scored during follow-up using 16 selected clinical scales or cognitive tests. RESULTS: The modelled evolutions of these scores obtained from 1243 observations in 265 patients recruited at the French National Referral Centre (50.1 years on average and 45.3% males) showed wide and heterogeneous variations in amplitude along the age-related progression of the disease. While the Backward Digit Span remained essentially stable, a linear deterioration of scores obtained using the Symbol Digit Numbers or Number of Errors of Trail Making Test B was detected from 25 to 75 years. In contrast, the largest score changes were observed at midlife using the Digit Cancellation Task. All other tests related to executive functions, memory performances, or global cognitive efficiency showed a rate of change accelerating especially at the advanced stage of the disease. Male gender, the presence of gait disorders or of some disability at baseline were found to predict earlier or large changes of 4 scores (Index of Sensitivity to Cueing, Delayed Total Recall, Initiation/Perseveration and Barthel Index) in a subgroup of individuals distinct form the rest of the sample. DISCUSSION: Cognitive alterations develop heterogeneously during the progression of CADASIL and vary largely according to the stage of the disease. These results suggest that not only the target population, study duration but also the stage of disease progression should be considered in preparing future clinical trials aimed at reducing cognitive decline in any such condition.

Episodic memory false recognition for familiar information in Alzheimer's disease.

Patients with Alzheimer's disease (AD) suffer from various types of memory distortions. We showed that confabulations are plausible memories, mainly reflecting the recall of repeated personal events mistakenly considered by confabulating patients as specific and unique events. The aim of this study is to see whether the notion that over-learned information interferes in episodic memory recall, as it does in confabulation, can be extended to another type of memory distortion, namely false recognition (i.e., a claim to recognize something that was not encountered previously). If this is the case, it should be expected that in an episodic recognition memory task AD patients produce more false recognition for well known non-studied, non to-be-remembered material than for unknown non-studied, non to-be-remembered material. In order to verify this prediction, AD patients and normal controls (NC) were administered two experiments. In Experiment 1, we presented pictures, of which half were supposed to be well known and the other half unknown monuments. For each picture, participants were asked to say whether or not the monument was known or not to them. Immediately following this semantic encoding task, participants were administered an episodic recognition memory task in which, in the same way as in the previous phase, among the non-studied items, half were supposed to be well known and the other half unknown. In Experiment 2 the same procedure was used employing well known and unknown symbols. It was predicted that AD patients make more false recognitions for non-studied well-known items than for non-studied unknown items. The results show that this is actually the case, suggesting that confusion between "uniqueness," i.e., specific unique events, and "multiplicity," i.e., repeated events, is also involved in false recognition.

Modeling the Cognitive Trajectory in CADASIL.

BACKGROUND: For developing future clinical trials in Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), it seems crucial to study the long-term changes of cognition. OBJECTIVE: We aimed to study the global trajectory of cognition, measured by the Mini-Mental State Examination (MMSE) and the Mattis Dementia Rating Scale (MDRS), along the course of CADASIL. METHODS: Follow-up data of 185 CADASIL patients, investigated at the French National Referral center CERVCO from 2003, were considered for analysis based on strict inclusion criteria. Assuming that the MMSE and the MDRS provide imprecise measures of cognition, the trajectory of a common cognitive latent process during follow-up was delineated using a multivariate latent process mixed model. After adjustment of this model for sex and education, the sensitivities of the two scales to cognitive change were compared. RESULTS: Analysis of the cognitive trajectory over a time frame of 60 years of age showed a decrease of performances with aging, especially after age of 50 years. This decline was not altered by sex or education but patients who graduated from high school had a higher mean cognitive level at baseline. The sensitivities of MMSE and MDRS scales were similar and the two scales suffered from a ceiling effect and curvilinearity. CONCLUSION: These data support that cognitive decline is not linear and mainly occurs after the age of 50 years during the course of CADASIL. They also showed that MMSE and MDRS scales are hampered by major limitations for longitudinal studies.

Predictors of clinical or cerebral lesion progression in adult moyamoya angiopathy.

OBJECTIVE: To identify independent predictors of clinical or cerebral lesion progression in a large sample of adult patients with moyamoya angiopathy (MMA) prior to decisions regarding revascularization surgery. METHODS: Ninety participants (median age, 37.5 years) were assessed at baseline and followed for a median time of 42.8 months. Incident ischemic and hemorrhagic strokes, death, as well as any incident ischemic and hemorrhagic lesions on MRI were recorded. Multiple demographic, clinical, and cerebral imaging measures at baseline were considered as potential predictors of clinical or cerebral tissue change at follow-up. Data were analyzed based on the Andersen-Gill counting process model, followed by internal validation of the prediction model. RESULTS: Among multiple potential predictive measures considered in the analysis, Asian origin, a history of TIAs, and a reduction in hemodynamic reserve, as detected by imaging, were found to be significantly associated with an increased risk of combined clinical and imaging events. While the model estimated the risk of clinical or cerebral lesion progression to be approximately 0.5% per year when none of these factors was present, this risk exceeded 20% per year when all factors were present. CONCLUSION: A simple combination of demographic, clinical, and cerebral perfusion imaging measures may aid in predicting the risk of incident stroke and cerebral lesion progression in adult patients with MMA. These results may help to improve therapeutic decisions and aid in the design of future trials in adults with this rare condition.