Temporoparietal hypometabolism in frontotemporal lobar degeneration and associated imaging diagnostic errors.

OBJECTIVE: To evaluate the cause of diagnostic errors in the visual interpretation of positron emission tomographic scans with fludeoxyglucose F 18 (FDG-PET) in patients with frontotemporal lobar degeneration (FTLD) and patients with Alzheimer disease (AD). DESIGN: Twelve trained raters unaware of clinical and autopsy information independently reviewed FDG-PET scans and provided their diagnostic impression and confidence of either FTLD or AD. Six of these raters also recorded whether metabolism appeared normal or abnormal in 5 predefined brain regions in each hemisphere-frontal cortex, anterior cingulate cortex, anterior temporal cortex, temporoparietal cortex, and posterior cingulate cortex. Results were compared with neuropathological diagnoses. SETTING: Academic medical centers. PATIENTS: Forty-five patients with pathologically confirmed FTLD (n=14) or AD (n=31). RESULTS: Raters had a high degree of diagnostic accuracy in the interpretation of FDG-PET scans; however, raters consistently found some scans more difficult to interpret than others. Unanimity of diagnosis among the raters was more frequent in patients with AD (27 of 31 patients [87%]) than in patients with FTLD (7 of 14 patients [50%]) (P=.02). Disagreements in interpretation of scans in patients with FTLD largely occurred when there was temporoparietal hypometabolism, which was present in 7 of the 14 FTLD scans and 6 of the 7 scans lacking unanimity. Hypometabolism of anterior cingulate and anterior temporal regions had higher specificities and positive likelihood ratios for FTLD than temporoparietal hypometabolism had for AD. CONCLUSIONS: Temporoparietal hypometabolism in FTLD is common and may cause inaccurate interpretation of FDG-PET scans. An interpretation paradigm that focuses on the absence of hypometabolism in regions typically affected in AD before considering FTLD is likely to misclassify a significant portion of FTLD scans. Anterior cingulate and/or anterior temporal hypometabolism indicates a high likelihood of FTLD, even when temporoparietal hypometabolism is present. Ultimately, the accurate interpretation of FDG-PET scans in patients with dementia cannot rest on the presence or absence of a single region of hypometabolism but rather must take into account the relative hypometabolism of all brain regions.

Validation of consensus panel diagnosis in dementia.

BACKGROUND: The clinical diagnosis of dementing diseases largely depends on the subjective interpretation of patient symptoms. Consensus panels are frequently used in research to determine diagnoses when definitive pathologic findings are unavailable. Nevertheless, research on group decision making indicates that many factors can adversely affect panel performance. OBJECTIVE: To determine conditions that improve consensus panel diagnosis. DESIGN: Comparison of neuropathologic diagnoses with individual and consensus panel diagnoses based on clinical scenarios only, fludeoxyglucose F 18 positron emission tomography images only, and scenarios plus images. SETTING: Expert and trainee individual and consensus panel deliberations using a modified Delphi method in a pilot research study of the diagnostic utility of fludeoxyglucose F 18 positron emission tomography. PATIENTS: Forty-five patients with pathologically confirmed Alzheimer disease or frontotemporal dementia. MAIN OUTCOME MEASURES: Statistical measures of diagnostic accuracy, agreement, and confidence for individual raters and panelists before and after consensus deliberations. RESULTS: The consensus protocol using trainees and experts surpassed the accuracy of individual expert diagnoses when clinical information elicited diverse judgments. In these situations, consensus was 3.5 times more likely to produce positive rather than negative changes in the accuracy and diagnostic certainty of individual panelists. A rule that forced group consensus was at least as accurate as majority and unanimity rules. CONCLUSIONS: Using a modified Delphi protocol to arrive at a consensus diagnosis is a reasonable substitute for pathologic information. This protocol improves diagnostic accuracy and certainty when panelist judgments differ and is easily adapted to other research and clinical settings while avoiding the potential pitfalls of group decision making.

Occupation attributes relate to location of atrophy in frontotemporal lobar degeneration.

Frontotemporal lobar degeneration (FTLD) often presents with asymmetric atrophy. We assessed whether premorbid occupations in FTLD patients were associated with these hemispheric asymmetries. In a multi-center chart review of 588 patients, occupation information was related to location of tissue loss or dysfunction. Patients with atrophy lateralized to the right had professions more dependent on verbal abilities than patients with left-lateralized or symmetrical atrophy. In a subgroup of 96 well-characterized patients with quantified neuroimaging data, the lateralization effect was localized to the temporal lobes and included verbal and mathematical ability. Patients whose professions placed high demands on language and mathematics had relatively preserved left temporal relative to right temporal volumes. Thus, occupation selection occurring in early adulthood is related to lateralized brain asymmetry in patients who develop FTLD decades later in the relatively deficient hemisphere. The finding suggests that verbal and mathematical occupations may have been pursued due to developmental right-lateralized functional impairment that precedes the neurodegenerative process. Alternatively, long-term engagement of activities associated with these occupations contributed to left-lateralized reserve, right-lateralized dysfunction, or both.

An open-label study of memantine treatment in 3 subtypes of frontotemporal lobar degeneration.

There are currently no Food and Drug Administration-approved treatments for frontotemporal lobar degeneration (FTLD). The objectives of this study were to explore the tolerability of memantine treatment in FTLD and to monitor for possible effects on behavior, cognition, and function. Forty-three individuals who met clinical criteria for FTLD [21 with frontotemporal dementia (FTD), 13 with semantic dementia (SD), and 9 with progressive nonfluent aphasia (PA)] received 26 weeks of open-label treatment with memantine at a target dose of 20 mg daily. Concurrent treatment with acetylcholinesterase inhibitors was prohibited. Cognitive and functional outcome measures included the Mini Mental State Examination, Alzheimer's Disease Assessment Scale-Cognitive (ADAS-cog), clinical dementia rating-sum of boxes, Neuropsychiatric Inventory (NPI), Frontal Behavior Inventory, Executive Interview (EXIT25), Texas Functional Living Scale (TFLS), Geriatric Depression Scale, and Unified Parkinson's Disease Rating Scale-motor scale. Most subjects were able to tolerate the target dose of memantine. A transient improvement was observed on the total NPI score primarily in the FTD group. Variable declines were observed on the ADAS-cog, EXIT25, Frontal Behavior Inventory, NPI, TFLS, and UPDRS scores. The FTD and SD groups declined on most of the cognitive and behavioral outcome measures, but remained stable on the UPDRS, whereas the progressive nonfluent aphasia group remained relatively stable on the ADAS-cog, NPI, and TFLS, but declined on the UPDRS. Memantine was well-tolerated in these subjects. Future placebo-controlled trials of memantine in FTLD are warranted and may have greater power to detect behavioral and cognitive effects if focused on the FTD and SD clinical syndromes.

Reduced hippocampal functional connectivity in Alzheimer disease.

OBJECTIVE: To determine if functional connectivity of the hippocampus is reduced in patients with Alzheimer disease. DESIGN: Functional connectivity magnetic resonance imaging was used to investigate coherence in the magnetic resonance signal between the hippocampus and all other regions of the brain. PARTICIPANTS: Eight patients with probable Alzheimer disease and 8 healthy volunteers. RESULTS: Control subjects showed hippocampal functional connectivity with diffuse cortical, subcortical, and cerebellar sites, while patients demonstrated markedly reduced functional connectivity, including an absence of connectivity with the frontal lobes. CONCLUSION: These findings suggest a functional disconnection between the hippocampus and other brain regions in patients with Alzheimer disease.

MMSE scores decline at a greater rate in frontotemporal degeneration than in AD.

The clinical diagnostic criteria for frontotemporal degeneration (FTD) include relative preservation of memory and visuospatial function, in contradistinction to characteristics of Alzheimer's disease (AD). The Mini-Mental State Examination (MMSE) contains items to assess these areas of cognition. In a retrospective case-control study of participants at two institutionally-based AD centers, we determined whether total MMSE and MMSE subscores would reflect the disease progression projected by the clinical criteria of FTD vs. AD. Participants were 44 subjects with FTD (7 pathologically confirmed) and 45 with pathologically confirmed AD. Each subject had at least two MMSEs with minimum inter-test intervals of 9 months. We compared annualized rates of change for total MMSE scores and cognitive domain subscores over time and between groups by two independent samples t-tests and proportion tests. The total MMSE score (p = 0.03) and language subscore (p = 0.02) showed a greater rate of decline for the FTD group than the AD group, although the constructional praxis item declined less rapidly in the FTD group (p = 0.018). Changes in MMSE subscores paralleled the clinical diagnostic criteria for FTD. The more rapid progression on the language subscore was observed in both language and behavioral variants of FTD.

Vascular disease and risk factors, rate of progression, and survival in Alzheimer's disease.

Two hundred forty-seven patients with early Alzheimer's disease were studied for the association of demographic, functional, and cognitive status and vascular comorbidities and risk factors present at index visit to rate of clinical disease progression over 3 years and to survival time. Patients who progressed to the moderate stage were designated fast progressors; those who remained in the early stage were designated slow progressors. At index visit, Mini-Mental State Exam score was significantly lower for the fast than the slow group; global impairment was significantly higher for the fast group. Cognitive scores showed greater annual decline in the fast group, and the fast group also had a greater annualized global change. The fast group had a shorter median survival time from onset, but age at onset, age at initial visit, history of heart problems, myocardial infarct, stroke, hypertension, diabetes, or past or current smoking did not differ between groups.

Convergence of connected language and SPECT in variants of frontotemporal lobar degeneration.

The characterization of frontotemporal lobar degeneration (FTLD) is complicated and not widely recognized. Connected language measures (ie, discourse) and functional neuroimaging may advance knowledge specifying early distinctions among frontal dementias. The present study examined the correspondence of discourse measures with (1) clinical diagnosis and (2) single photon emission computed tomography (SPECT) imaging. Nineteen subjects were selected from Alzheimer's Disease Center (ADC) participants if they were diagnosed with early-stage frontotemporal lobar degeneration and also underwent single photon emission computed tomography and discourse evaluation. First, clinical diagnoses given by specialists at an Alzheimer's Disease Center were compared with the discourse-based diagnostic profiles. Secondly, compromised brain regions that were predicted from discourse profiles were compared with SPECT findings. Results revealed a significant correspondence between the ADC diagnosis and the discourse-based diagnoses. Also, the discourse profiles across frontotemporal lobar degeneration subtypes were consistently associated with distinctive patterns of SPECT hypometabolism in the right frontal, left frontal, or left temporal lobes. These findings suggest that discourse methods may be systematized to provide an efficient adjunct measure beyond the traditional word and sentential level measures. Objectifying complex language performance may contribute to early detection and differentiation among frontotemporal lobar degeneration variants because consensus in the literature states that language is a core disturbance of frontotemporal lobar degeneration.

Referral patterns for syndromes associated with frontotemporal lobar degeneration.

We compared demographics of subjects diagnosed with frontotemporal degeneration (FTD) at a group of 5 clinics specializing in this non-Alzheimer dementia against those subjects diagnosed at standard Alzheimer disease centers, to determine any differences in referral patterns between such clinics. Of the two major phenotypes of FTD, behavior and language, the latter more frequently presented to the specialty clinics (46% of FTD diagnoses versus 19%, P < 0.001). Mean age at onset for the behavioral presentation phenotype was one year younger at the specialty clinics (P < 0.01). Mean age at onset for the language phenotype was 3 years older (P < 0.001) than for the behavioral phenotype at standard centers but did not differ between the two evaluating groups. Cases with FTD referred to all of the dementia evaluation sites in this study did not differ significantly from those previously reported in the literature. Clinics specializing in FTD recruit more language presentation cases. There were statistical but not clinically significant differences in ages at onset.

Frontotemporal lobar degeneration with motor neuron disease-type inclusions predominates in 76 cases of frontotemporal degeneration.

This report presents the largest series of consecutive, neuropathologically confirmed cases of frontotemporal degeneration (FTD). Prior studies have found dementia lacking distinctive histology (DLDH) to be the most common pathology underlying the clinical diagnosis of FTD. In this series of 76 cases, 29 (38%) were found to have frontotemporal lobar degeneration with motor neuron disease-type inclusions (FTLD-MND-type) or FTLD-MND (with ALS), the most common neuropathological classification in our series. Only eight (11%) were classified as Pick's disease. Several cases originally designated as DLDH could be reclassified as FTLD-MND-type based on current recommendations for classification of FTD.

Lateralization on neuroimaging does not differentiate frontotemporal lobar degeneration from Alzheimer's disease.

Lateralization on neuroimaging was compared in cases of frontotemporal lobar degeneration (FTLD; n = 10) and cases of definite Alzheimer's disease (AD; n = 17). All of the cases were pathologically confirmed and semi-quantitative and statistical parametric mapping methods were employed. Seven of the 10 FTLD cases had lateralization on at least one neuroimaging modality: single photon emission computerized tomography (SPECT), MRI, or CT. All 6/6 FTLD cases with SPECT showed lateralization. MRI results generally agreed with SPECT findings. Three of 4 FTLD cases had lateralized atrophy on CT. For the AD cases, 10/17 SPECTs, 2/7 MRIs, and 1/9 CTs showed lateralized findings. Of the neuroimaging modalities utilized, SPECT was the most sensitive in detecting lateralization.

Can alzheimer's disease and dementias with Lewy bodies be distinguished clinically?

To determine if Alzheimer's disease (AD), its Lewy body (LB) variant (LBV), and diffuse LB disease (DLBD) are distinguishable at initial clinical evaluation, data from autopsy-confirmed AD, LBV, and DLBD were examined. No significant differences were found in age at onset, age at death, total duration of illness, duration of illness before initial visit, duration of illness from initial visit to death, or severity of illness at initial evaluation. Hallucinations and delusions were significantly more frequent for LBV and DLBD, respectively, than for AD, and falls were more frequent for DLBD than for AD. Extrapyramidal symptoms (EPS) were less frequent in neuroleptic-free AD subjects than in LB subjects; the percentage of AD patients with EPS after neuroleptic exposure was less than that among LB patients. Seizures were significantly more common for DLBD than for AD or LBV. LB dementias differed from AD at initial evaluation, with more frequent hallucinations and delusions, EPSs, and seizures, and longitudinally in neuroleptic sensitivity, but the data did not distinguish LBV from DLBD.

Reduction in levels of 24S-hydroxycholesterol by statin treatment in patients with Alzheimer disease.

BACKGROUND: The statin treatment of dyslipidemia is associated with a reduced risk of development of Alzheimer disease (AD). The effect may be mediated by a reduction in cholesterol biosynthesis in the brain, by lowering levels of apolipoprotein E (apo E)-containing lipoproteins, or by pleitropic effects such as reduction in beta-amyloid production. In the brain, cholesterol from damaged or dying neurons is converted to 24S-hydroxycholesterol by cholesterol 24-hydroxylase (CYP46). The oxysterol is subsequently transferred across the blood-brain barrier, transported to the liver by low-density lipoproteins (LDLs), and excreted as bile acids. Most of plasma 24S-hydroxycholesterol is derived from brain cholesterol; consequently, plasma levels of the oxysterol reflect brain cholesterol catabolism. OBJECTIVE: To examine the effect of 3 statins and a nonstatin hypolipidemic agent on plasma levels of 24S-hydroxycholesterol and apo E in patients with AD. STUDY DESIGN: The study had a sequential parallel design. It was open-labeled and involved lipoprotein and 24S-hydroxycholesterol evaluations at baseline and at 6 weeks of treatment with 40 mg of lovastatin, simvastatin, or pravastatin sodium per day, or 1 g of extended-release niacin per day. Blood samples were drawn after a 12-hour fast for measurement of plasma sterols, oxysterols, lipoprotein cholesterol, and levels of apo E, plasma transaminases, and glucose. Measurements were made at baseline and during treatment. RESULTS: Statin treatment reduced levels of plasma lathosterol by 49.5%, 24S-hydroxycholesterol by 21.4%, LDL cholesterol by 34.9%, and total cholesterol by 25%. The ratios of lathosterol-campesterol and 24S-hydroxycholesterol-LDL cholesterol were reduced significantly, but the ratio of 24S-hydroxycholesterol-total cholesterol was unchanged. Extended-release niacin also significantly reduced levels of 24S-hydroxycholesterol by 10% and LDL cholesterol by 18.1%. None of the agents lowered plasma concentration of apo E. CONCLUSIONS: Statins lowered levels of plasma 24S-hydroxycholesterol without affecting levels of apo E. The LDL lowering was more pronounced than 24S-hydroxycholesterol reductions. The effect of statins on LDL partially explains the reduction of plasma oxysterol level.