Mario F. Mendez

Classification of primary progressive aphasia and its variants

This article provides a classification of primary progressive aphasia (PPA) and its 3 main variants to improve the uniformity of case reporting and the reliability of research results. Criteria for the 3 variants of PPA—nonfluent/agrammatic, semantic, and logopenic—were developed by an international group of PPA investigators who convened on 3 occasions to operationalize earlier published clinical descriptions for PPA subtypes. Patients are first diagnosed with PPA and are then divided into clinical variants based on specific speech and language features characteristic of each subtype. Classification can then be further specified as “imaging-supported” if the expected pattern of atrophy is found and “with definite pathology” if pathologic or genetic data are available. The working recommendations are presented in lists of features, and suggested assessment tasks are also provided. These recommendations have been widely agreed upon by a large group of experts and should be used to ensure consistency of PPA classification in future studies. Future collaborations will collect prospective data to identify relationships between each of these syndromes and specific biomarkers for a more detailed understanding of clinicopathologic correlations.

Neurobehavioral changes associated with caudate lesions.

We report behavioral and cognitive characteristics of 12 patients with caudate nuclei lesions, 11 unilateral and one bilateral. These patients developed an acute behavioral change characterized by apathy, disinhibition, or a major affective disturbance. The pattern of personality change correlated with size and location of lesion within the caudate but not the laterality. Seven patients were further compared with matched controls on a series of neuropsychological tests. Their performance was impaired on tasks requiring planning and sequencing. They had short attention spans and decreased free recall of episodic and semantic items with good recognition memory scores. Similar behavioral and cognitive changes also occur in early Huntingtons disease, frontal-lesioned patients, and caudate-lesioned animals, and correspond to disturbances of specific frontal-caudate circuits. These results implicate the caudate nuclei in mediating prefrontal behaviors and possibly in the conceptual integration of memories.

Development of Scoring Criteria for the Clock Drawing Task in Alzheimer's Disease

To investigate the reliability and validity of freehand clock drawings, a frequently used measure of constructional apraxia, in patients with Alzheimers disease.

Posterior Cortical Atrophy: Clinical Characteristics and Differences Compared to Alzheimer’s Disease

Background: Predominant and progressive complex visual disorders are often due to posterior cortical atrophy (PCA), a rare early-onset dementing syndrome presenting with visual complaints. In clinicopathological studies, PCA is most commonly considered a form of Alzheimer’s disease (AD); no prior study has evaluated clinical differences between PCA and AD. Methods: This study identified 15 patients who presented with progressive complex visual disorders and predominant occipitoparietal hypoperfusion on SPECT. These patients were retrospectively compared on clinical variables with 30 patients with clinically probable AD matched for gender, age and duration of illness. Results: The PCA patients presented with alexia, elements of Balint’s syndrome, apperceptive visual agnosia, dressing apraxia and environmental disorientation along with elements of Gerstmann’s syndrome. Compared to the AD patients, the 15 PCA patients (mean age of onset 58 years, range 51–64) had significantly better verbal fluency, less memory difficulty, more depression and greater insight into their illness but similar familial and apolipoprotein E risk factors. In the PCA patients, MRI often showed occipitoparietal atrophy without detectable mesiotemporal atrophy. Conclusions: PCA is a distinct clinical syndrome and not just AD with prominent visual deficits. Compared to AD controls, PCA patients have better language and memory but more insight and depression and more posterior atrophy on MRI. These results indicate clinical criteria for the diagnosis of PCA and recommend specific interventions such as visual aids and antidepressant medications. Similar risk factors and course suggest that PCA is most commonly an early-onset posteriorly shifted AD variant.

An investigation of moral judgement in frontotemporal dementia.

Objective:To investigate the basis of disturbed moral judgment in patients with frontotemporal dementia (FTD). Background:FTD is characterized by difficulty in modulating social behavior. Patients lack social propriety and may perform sociopathic acts. In addition, FTD patients often lack empathy for others. These findings suggest alterations in the nature of morality in patients with FTD. Method:We administered an inventory of moral knowledge and two moral dilemmas to 26 patients with the frontal variant of FTD, 26 patients with Alzheimer disease (AD), and 26 normal control subjects. The FTD patients met Consensus Criteria for FTD and had corroborative frontal abnormalities on functional neuroimaging. The FTD and AD patients were comparably impaired on dementia measures. Results:All these groups showed the retention of knowledge for moral behavior and the ability to make “impersonal” moral judgments. In contrast, the FTD patients were impaired in their ability to make immediate, emotionally based moral judgments compared with the patients with AD and the normal control subjects. Conclusions:These findings are consistent with an attenuation of the automatic emotional identification with others that is part of the innate moral sense. Such a disturbance may result from neurodegenerative disease affecting the ventromedial frontal cortex.

Pick's disease versus Alzheimer's disease A comparison of clinical characteristics

The clinical recognition of Picks disease depends on its differentiation from Alzheimers disease (AD). To identify distinguishing clinical features, we reviewed the clinical records of 21 patients with pathologically confirmed Picks disease and matched them by sex, age of onset, and duration of dementia with 42 patients having pathologically confirmed AD. In the absence of temporal or frontal lobar atrophy on CTs, all the Pick patients and none of the AD patients had three of five clinical features: presenile onset (before age 66), an initial personality change, hyperorality, disinhibition, and roaming behavior. In addition, the Pick patients had a tendency toward reiterative and other speech disturbances. These findings suggest that Pick patients are potentially distinguishable from AD patients on the basis of clinical manifestations.

Diagnostic criteria for the behavioral variant of frontotemporal dementia (bvFTD): Current limitations and future directions

The most widely established diagnostic criteria for the behavioral variant of frontotemporal dementia have now been in use for almost a decade. Although consensus criteria have provided a much needed standard for frontotemporal dementia research, a growing body of evidence suggests that revisions are needed to improve their applicability. In this article, we discuss the limitations of current diagnostic criteria and propose the establishment of an international consortium to revise diagnostic and research criteria for the behavioral variant of frontotemporal dementia.

Development of methodology for conducting clinical trials in frontotemporal lobar degeneration

To design clinical trials for the frontotemporal lobar degenerations (FTLD), knowledge about measurement of disease progression is needed to estimate power and enable the choice of optimal outcome measures. The aim here was to conduct a multicentre, 1 year replica of a clinical trial in patients with one of four FTLD syndromes, behavioural variant frontotemporal dementia (bvFTD), progressive nonfluent aphasia (PNFA), progressive logopenic aphasia (PLA) and semantic dementia (SMD). Patients with one of the four FTLD syndromes were recruited from five academic medical centres over a 2 year period. Standard operationalized diagnostic criteria were used. In addition to clinical inclusion and exclusion criteria, patients were required to exhibit focal frontal, temporal or insular brain atrophy or dysfunction by neuroimaging. Patients underwent neuropsychological, functional, behavioural, neurological and MR imaging assessment at baseline and approximately 12 months later. Potential outcome measures were examined for their rates of floor and ceiling values at baseline and end of study, their mean changes and variances. The neuropsychological tests were combined into two cognitive composites -- one for language functions and the other for executive functions. There were 107 patients who underwent baseline assessment and 78 who completed a follow-up assessment within 10-16 months. Two global measures, the FTLD-modified Clinical Dementia Rating (FTLD-modified CDR) and the Clinical Global Impression of Change (CGIC) demonstrated decline in the majority of patients. Several cognitive measures showed negligible floor or ceiling scores either at baseline or follow-up. Scores declined at follow-up in the majority of patients. The cognitive, executive and combined composites were shown to be sensitive to change across all FTLD syndromes. Patients improved at follow-up on the behavioural scales -- the Frontal Behavioural Inventory (22%) and the Neuropsychiatric Inventory (28%) -- suggesting that these instruments may not be ideal for clinical trial use. It was feasible to recruit FTLD patients in a simulated multi-centre trial. There are several candidate outcome measures -- including the FTLD-CDR and the cognitive composites -- that could be used in clinical trials across the spectrum of FTLD.

Lifespan trajectory of myelin integrity and maximum motor speed.

OBJECTIVE Myelination of the human brain results in roughly quadratic trajectories of myelin content and integrity, reaching a maximum in mid-life and then declining in older age. This trajectory is most evident in vulnerable later myelinating association regions such as frontal lobes and may be the biological substrate for similar trajectories of cognitive processing speed. Speed of movement, such as maximal finger tapping speed (FTS), requires high-frequency action potential (AP) bursts and is associated with myelin integrity. We tested the hypothesis that the age-related trajectory of FTS is related to brain myelin integrity. METHODS A sensitive in vivo MRI biomarker of myelin integrity (calculated transverse relaxation rates (R(2))) of frontal lobe white matter (FLwm) was measured in a sample of very healthy males (N=72) between 23 and 80 years of age. To assess specificity, R(2) of a contrasting early-myelinating region (splenium of the corpus callosum) was also measured. RESULTS FLwm R(2) and FTS measures were significantly correlated (r=.45, p<.0001) with no association noted in the early-myelinating region (splenium). Both FLwm R(2) and FTS had significantly quadratic lifespan trajectories that were virtually indistinguishable and both reached a peak at 39 years of age and declined with an accelerating trajectory thereafter. CONCLUSIONS The results suggest that in this very healthy male sample, maximum motor speed requiring high-frequency AP burst may depend on brain myelin integrity. To the extent that the FLwm changes assessed by R(2) contribute to an age-related reduction in AP burst frequency, it is possible that other brain functions dependent on AP bursts may also be affected. Non-invasive measures of myelin integrity together with testing of basic measures of processing speed may aid in developing and targeting anti-aging treatments to mitigate age-related functional declines.

Preliminary findings : Behavioral worsening on donepezil in patients with frontotemporal dementia

OBJECTIVE The objective of this study was to evaluate donepezil, an acetylcholinesterase inhibitor, in the treatment of frontotemporal dementia (FTD). METHODS Twelve patients with FTD who received donepezil for six months were compared with 12 FTD controls on behavioral measures. RESULTS The groups did not differ on most variables at baseline or at six months; however, the donepezil group had greater worsening on the FTD Inventory. Four treated patients had increased disinhibited or compulsive acts, which abated with discontinuation of the medication. CONCLUSION There were no changes in global cognitive performance or dementia severity; however, a subgroup of patients with FTD can experience worsening of symptoms with donepezil.