Neuropsychological and cerebral metabolic function in early vs late onset dementia of the Alzheimer type

Age of Symptom Onset and Longitudinal Course of Sporadic Alzheimer's Disease, Frontotemporal Dementia, and Vascular Dementia: A Systematic Review and Meta-Analysis

BACKGROUND

Understanding how the age of dementia symptom onset affects the longitudinal course of dementia can assist with prognosis and care planning.

OBJECTIVE

To synthesize evidence regarding the relationship of age of symptom onset with the longitudinal course of sporadic Alzheimer's disease (AD), vascular dementia (VaD), and frontotemporal dementia (FTD).

METHODS

We searched Medline, CINAHL, Embase, PsycINFO, PubMed, and Scopus for longitudinal studies that examined the impact of sporadic AD, VaD, or FTD symptom onset age on measures of cognition, function, or behavioral symptoms. Studies that examined age at diagnosis only were excluded. Quantitative meta-analysis was conducted where studies reported sufficient data for pooling.

RESULTS

Thirty studies met all inclusion criteria (people with AD (n = 26), FTD (n = 4)) though no studies examined VaD. Earlier onset of AD was associated with more rapid annual cognitive decline (estimate = -0.07; 95% CI -0.14 to 0.00; p = 0.045). Most studies that stratified their sample reported that younger AD onset (usually <  65 years) was associated with more rapid cognitive decline. Other evidence was inconclusive.

CONCLUSION

Younger people with AD appear to have a poorer prognosis in terms of faster cognitive decline than older people with AD. More research is required to determine the impact of symptom onset age in VaD and FTD, and on functional decline in all dementias.

The Longitudinal Early-onset Alzheimer's Disease Study (LEADS): Framework and methodology

Patients with early-onset Alzheimer's disease (EOAD) are commonly excluded from large-scale observational and therapeutic studies due to their young age, atypical presentation, or absence of pathogenic mutations. The goals of the Longitudinal EOAD Study (LEADS) are to (1) define the clinical, imaging, and fluid biomarker characteristics of EOAD; (2) develop sensitive cognitive and biomarker measures for future clinical and research use; and (3) establish a trial-ready network. LEADS will follow 400 amyloid beta (Aβ)-positive EOAD, 200 Aβ-negative EOnonAD that meet National Institute on Aging-Alzheimer's Association (NIA-AA) criteria for mild cognitive impairment (MCI) or AD dementia, and 100 age-matched controls. Participants will undergo clinical and cognitive assessments, magnetic resonance imaging (MRI), [18 F]Florbetaben and [18 F]Flortaucipir positron emission tomography (PET), lumbar puncture, and blood draw for DNA, RNA, plasma, serum and peripheral blood mononuclear cells, and post-mortem assessment. To develop more effective AD treatments, scientists need to understand the genetic, biological, and clinical processes involved in EOAD. LEADS will develop a public resource that will enable future planning and implementation of EOAD clinical trials.

Resting-state EEG alpha/theta power ratio discriminates early-onset Alzheimer's disease from healthy controls

OBJECTIVES

The present study aims to compare early-onset Alzheimer's disease (EOAD) patients with healthy controls (HC), and late-onset Alzheimer's disease (LOAD) patients using resting-state delta, theta, alpha, and beta oscillations and provide a cut-off score of alpha/theta ratio to discriminate individuals with EOAD and young HC.

METHODS

Forty-seven individuals with EOAD, 51 individuals with LOAD, and demographically-matched 49 young and 51 older controls were included in the study. Spectral-power analysis using Fast-Fourier Transformation (FFT) is performed on resting-state electroencephalography (EEG) data. Delta, theta, alpha, and beta oscillations compared between groups and Receiver Operating Characteristic (ROC) curve analysis was conducted.

RESULTS

Compared to healthy controls individuals with EOAD showed an increase in slow frequency bands and a decrease in fast frequency bands. Frontal alpha/theta power ratio is the best discriminating value between EOAD and young HC with the sensitivity and specificity greater than 80% with area under the curve (AUC) 0.881.

CONCLUSIONS

EOAD display more widespread and severe electrophysiological abnormalities than LOAD and HC which may reflect more pronounced pathological burden and cholinergic deficits in EOAD. Additionally, the alpha/theta ratio can discriminate EOAD and young HC successfully.

SIGNIFICANCE

This study is the first to report that resting-state EEG power can be a promising marker for diagnostic accuracy between EOAD and healthy controls.

rCBF and cognitive impairment changes assessed by SPECT and ADAS-cog in late-onset Alzheimer's disease after 18 months of treatment with the cholinesterase inhibitors donepezil or galantamine

Late-onset Alzheimer's disease (AD) differs substantially from early-onset AD. In this cross sectional study we investigated brain perfusion changes after 18 months of treatment with cholinesterase inhibitors (ChEIs) donepezil or galantamine. Twenty-five drug-naïve late-onset AD patients were recruited from outpatient clinics. We examined brain perfusion using single photon emission computed tomography (SPECT) and used three-dimensional stereotactic surface projection (3D-SSP) and the stereotactic extraction estimation method (SEE) level 3 to analyze classified gyrus level segments. We assessed cognitive function using the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) grouped into three subgroup domains, language, memory, and praxis. In the follow-up data, some regions were further hypoperfused, reflecting worsening of the disease, while other regions showed alleviated hypoperfusion, potentially related to the ChEIs treatment. Regional cerebral blood flow (rCBF) decreased in the parietal cortex and increased in the frontal and the limbic cortices. Increased hypoperfusion significantly correlated with ADAS-cog scores changes were seen in the superior parietal lobule, inferior parietal lobule, angular gyrus, and supramarginal gyrus of the parietal cortex. Alleviated hypoperfusion significantly related to recovery of ADAS-cog scores were seen in the rectal and paracentral lobule of the frontal cortex, and the anterior cingulate of the limbic cortex. These regions showed significant relationships with total ADAS-cog and language, memory and praxis subscales scores. The current longitudinal study indicates prominent rCBF changes and their relationships with changes in ADAS-cog scores in late-onset AD patients.

Relationships between cognitive impairment on ADAS-cog and regional cerebral blood flow using SPECT in late-onset Alzheimer's disease

The aim of this study was to examine brain hypoperfusion and its relationship with cognitive dysfunction in late-onset Alzheimer's disease (AD). Forty patients with late-onset AD and not receiving acetylcholinesterase inhibitors were recruited from outpatient clinics. We examined cognitive function using the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) and brain perfusion using single-photon emission computed tomography, and analyzed classified gyrus level segments with three-dimensional stereotactic surface projection and the stereotactic extraction estimation method level 3. ADAS-cog subscales were grouped into three domains: language, memory, and praxis. Patients with late-onset AD showed an apparent reduction in regional cerebral blood flow (rCBF) with a z score >1.5 in the frontal, temporal, and limbic lobes, with lesser reduction in the parietal and occipital lobes. Although hypoperfusion in the orbital, rectal, and subcallosal gyri of the frontal lobe was prominent, rCBF in the inferior frontal gyrus of the frontal lobe was significantly correlated with ADAS-cog total and language and praxis subscale scores. The parahippocampal gyrus of the limbic lobe was also significantly correlated with the ADAS-cog total, language, and praxis subscale scores. Additionally, the cingulate of the limbic lobe was significantly related with ADAS-cog memory. In spite of lesser hypoperfusion, the posterior cingulate gyrus of the limbic lobe was significantly related with ADAS-cog total, language, and memory subscale scores. Further, each subdivision of ADAS-cog was found to be related with various brain regions.

Beta-amyloid deposition in patients with major depressive disorder with differing levels of treatment resistance: a pilot study

BACKGROUND

Lack of treatment response in patients with late-life depression is common. The role of brain beta-amyloid (Aβ) deposition in treatment outcome in subjects with late-life depression remains unclear. The present study aimed to investigate brain Aβ deposition in patients with major depressive disorder (MDD) with differing treatment outcomes in vivo using ¹⁸F-florbetapir imaging. This study included 62 MDD patients and 18 healthy control subjects (HCs).We first employed the Maudsley staging method (MSM) to categorize MDD patients into two groups according to treatment response: mild treatment resistance (n = 29) and moderate-to-severe treatment resistance (n = 33).The standard uptake value ratio (SUVR) of each volume of interest was analysed, and voxel-wise comparisons were made between the MDD patients and HCs. Vascular risk factors, serum homocysteine level, and apolipoprotein E (ApoE) genotype were also determined.

RESULTS

The MDD patients with moderate-to-severe treatment resistance had higher ¹⁸F-florbetapir SUVRs than the HCs in the parietal region (P < 0.01). Voxel-wise comparisons further demonstrated elevated SUVRs in MDD patients with moderate-to-severe treatment resistance in the precuneus, parietal, temporal, and occipital regions. The MDD patients with mild treatment resistance were found to have increased ¹⁸F-florbetapir uptake mainly in the left frontal and parietal regions as compared with the HCs. In addition, voxel-to-voxel correlation analysis showed that brain Aβ deposition was correlated positively with MSM score in the occipital region. ¹⁸F-florbetapir SUVRs were correlated negatively with Mini Mental Status Examination (MMSE) score in the sample of all MDD patients (r = -0.355, P = 0.005).

CONCLUSIONS

This study provided preliminary evidence that region-specific Aβ deposition was present in some (but not all) MDD patients, especially in those with moderate-to-severe treatment resistance, and their depressive symptoms may represent prodromal manifestations of Alzheimer's disease (AD). Depressive symptomatology in old age, particularly in subjects with a poor treatment response, may underscore early changes of AD-related pathophysiology.

Measuring Fluid Intelligence in Healthy Older Adults

The present study evaluated subjective and objective cognitive measures as predictors of fluid intelligence in healthy older adults. We hypothesized that objective cognitive measures would predict fluid intelligence to a greater degree than self-reported cognitive functioning. Ninety-three healthy older (>65 years old) community-dwelling adults participated. Raven's Advanced Progressive Matrices (RAPM) were used to measure fluid intelligence, Digit Span Sequencing (DSS) was used to measure working memory, Trail Making Test (TMT) was used to measure cognitive flexibility, Design Fluency Test (DFT) was used to measure creativity, and Tower Test (TT) was used to measure planning. The Cognitive Failures Questionnaire (CFQ) was used to measure subjective perceptions of cognitive functioning. RAPM was correlated with DSS, TT, and DFT. When CFQ was the only predictor, the regression model predicting fluid intelligence was not significant. When DSS, TMT, DFT, and TT were included in the model, there was a significant change in the model and the final model was also significant, with DFT as the only significant predictor. The model accounted for approximately 20% of the variability in fluid intelligence. Our findings suggest that the most reliable means of assessing fluid intelligence is to assess it directly.

Mapping the Progression of Atrophy in Early- and Late-Onset Alzheimer's Disease

The term early-onset Alzheimer's disease (EOAD) identifies patients who meet criteria for AD, but show onset of symptoms before the age of 65. We map progression of gray matter atrophy in EOAD patients compared to late-onset AD (LOAD). T1-weighted MRI scans were obtained at diagnosis and one-year follow-up from 15 EOAD, 10 LOAD, and 38 age-matched controls. Voxel-based and tensor-based morphometry were used, respectively, to assess the baseline and progression of atrophy. At baseline, EOAD patients already showed a widespread atrophy in temporal, parietal, occipital, and frontal cortices. After one year, EOAD had atrophy progression in medial temporal and medial parietal cortices. At baseline, LOAD patients showed atrophy in the medial temporal regions only, and, after one year, an extensive pattern of atrophy progression in the same neocortical cortices of EOAD. Although atrophy mainly involved different lateral neocortical or medial temporal hubs at baseline, it eventually progressed along the same brain default-network regions in both groups. The cortical region showing a significant progression in both groups was the medial precuneus/posterior cingulate.

Early-onset and late-onset Alzheimer's disease are associated with distinct patterns of memory impairment

The goal of this study was to investigate the specific patterns of memory breakdown in patients suffering from early-onset Alzheimer's disease (EOAD) and late-onset Alzheimer's disease (LOAD). Twenty EOAD patients, twenty LOAD patients, twenty matched younger controls, and twenty matched older controls participated in this study. All participants underwent a detailed neuropsychological assessment, an MRI scan, an FDG-PET scan, and AD patients had biomarkers as supporting evidence of both amyloïdopathy and neuronal injury. Results of the neuropsychological assessment showed that both EOAD and LOAD groups were impaired in the domains of memory, executive functions, language, praxis, and visuoconstructional abilities, when compared to their respective control groups. EOAD and LOAD groups, however, showed distinct patterns of memory impairment. Even though both groups were similarly affected on measures of episodic, short term and working memory, in contrast semantic memory was significantly more impaired in LOAD than in EOAD patients. The EOAD group was not more affected than the LOAD group in any memory domain. EOAD patients, however, showed significantly poorer performance in other cognitive domains including executive functions and visuoconstructional abilities. A more detailed analysis of the pattern of semantic memory performance among patient groups revealed that the LOAD was more profoundly impaired, in tasks of both spontaneous recall and semantic recognition. Voxel-Based Morphometry (VBM) analyses showed that impaired semantic performance in patients was associated with reduced gray matter volume in the anterior temporal lobe (ATL) region, while PET-FDG analyses revealed that poorer semantic performance was associated with greater hypometabolism in the left temporoparietal region, both areas reflecting key regions of the semantic network. Results of this study indicate that EOAD and LOAD patients present with distinct patterns of memory impairment, and that a genuine semantic impairment may represent one of the clinical hallmarks of LOAD.

Sphingomyelin SM(d18:1/18:0) is significantly enhanced in cerebrospinal fluid samples dichotomized by pathological amyloid-β42, tau, and phospho-tau-181 levels

Alzheimer's disease (AD) is a severe and chronic neurodegenerative disorder of the brain. The laboratory diagnosis is limited to the analysis of three biomarkers in cerebrospinal fluid (CSF): amyloid-β42 (Aβ42), total tau, and phospho-tau-181 (P-tau-181). However, there is a need to find more biomarkers in CSF that can improve the sensitivity and specificity. The aim of the present study was to analyze endogenous small metabolites (metabolome) in the CSF, which may provide potentially new insights into biochemical processes involved in AD. One hundred CSF samples were dichotomized by normal (n = 50) and pathological decreased Aβ42 and increased tau and P-tau-181 levels (n = 50; correlating to an AD-like pathology). These CSF samples were analyzed using the AbsoluteIDQ® p180 Kit (BIOCRATES Life Sciences), which included 40 acylcarnitines, 21 amino acids, 19 biogenic amines, 15 sphingolipids, and 90 glycerophospholipids. Our data show that two sphingomyelins (SM (d18:1/18:0) and SM (d18:1/18:1)), 5 glycerophospholipids (PC aa C32:0, PC aa C34:1, PC aa C36:1, PC aa C38:4 and PC aa C38:6), and 1 acylcarnitine (C3-DC-M/C5-OH) were significantly altered in the CSF with pathological "AD-like pathology". Sphingomyelin SM (d18:1/18:0) proved to be a specific (76%) and sensitive (66%) biomarker with a defined cut-off of 546 nM. Correct diagnoses for 21 out of 32 unknown samples could be achieved using this SM (d18:1/18:0) cut-off value. In conclusion, the sphingolipid SM (d18:1/18:0) is significantly increased in CSF of patients displaying pathological levels of Aβ42, tau, and P-tau-181.

Alzheimer's disease first symptoms are age dependent: Evidence from the NACC dataset

INTRODUCTION

Determining the relationship between age and Alzheimer's disease (AD) presentation is important to improve understanding and provide better patient services.

METHODS

We used AD patient data (N = 7815) from the National Alzheimer Coordinating Center database and multinomial logistic regression to investigate presentation age and first cognitive/behavioral symptoms.

RESULTS

The odds of having a nonmemory first cognitive symptom (including impairment in judgment and problem solving, language, and visuospatial function) increased with younger age (P < .001, all tests). Compared with apathy/withdrawal, the odds of having depression and "other" behavioral symptoms increased with younger age (P < .02, both tests), whereas the odds of having psychosis and no behavioral symptom increased with older age (P < .001, both tests).

DISCUSSION

There is considerable heterogeneity in the first cognitive/behavioral symptoms experienced by AD patients. Proportions of these symptoms change with age with patients experiencing increasing nonmemory cognitive symptoms and more behavioral symptoms at younger ages.

Wechsler Adult Intelligence Scale-III profile in the early stages of Alzheimer's disease: performance in subtests sensitive to and resistant to normal decline with ageing

AIM

This study examined the significance of age-related subtest scores from the Japanese version of the Wechsler Adult Intelligence Scale-III in patients in the early stages of Alzheimer's disease (AD).

METHODS

The subjects of this study included 58 elderly Japanese persons classified into two groups: AD group (n = 29) and control group (n = 29). These groups did not differ in age, years of education, gender ratio, Hasegawa's Dementia Scale-Revised score, or Full-Scale IQ score. No subject scored below the cut-off point on Hasegawa's Dementia Scale-Revised, a frequently used dementia screen test in Japan.

RESULTS

At the index score level, General Ability Index scores were the only scores that differed significantly between the groups, with the AD group scoring significantly lower than the control group (P < 0.05, Hedges' g = 0.54). At the subtest level, information scores were the only scores that differed significantly between the groups, with the AD group significantly lower than the control group (P < 0.01, Hedges' g = 0.74).

CONCLUSION

The General Ability Index is a composite score that deducts components of working memory and processing speed, which are sensitive to decline with normal ageing, from the Full-Scale IQ. It also served as a subtest measuring crystallized intelligence, especially of acquired knowledge of general and factual information. Therefore, the results of this study seem to suggest that Wechsler Adult Intelligence Scale-III profile of very early AD may be characterized by weak performance on subtests normally resistant to decline with ageing.

Neuropsychological performance and conversion to Alzheimer's disease in early- compared to late-onset amnestic mild cognitive impairment: CREDOS study

BACKGROUND

Amnestic mild cognitive impairment (aMCI) is regarded as a prodromal stage of Alzheimer's disease (AD). Given that patients with early-onset AD (EOAD) and with late-onset AD (LOAD) are known to have different clinical courses, symptoms and neuroimaging findings, early-onset (EOMCI) and late-onset aMCI (LOMCI) might be expected to have similar differences as EOAD versus LOAD.

METHODS

Our study involving 425 patients with aMCI (124 EOMCI, 301 LOMCI), who were followed for around 1.5 years, and 958 normal control subjects (NC) investigated neuropsychological characteristics and prediction of progression to AD in patients with EOMCI versus LOMCI. Neuropsychological scores were compared between EOMCI, LOMCI and NC with analyses of covariance controlling age, gender, education and disease duration. The risk of AD conversion was evaluated by Cox proportional hazard analyses.

RESULTS

The baseline neuropsychological performances were comparable between EOMCI and LOMCI. Visuospatial memory for EOMCI and verbal memory scores for LOMCI were significant predictors of AD conversion.

CONCLUSION

Our study indicates that EOMCI with visuospatial memory impairment, which implies underlying right predominant pathology, and LOMCI with poor verbal memory, which suggests underlying left predominant pathology, are individual conditions at an increased risk of conversion to AD.

Neuropsychological and neuroimaging markers in early versus late-onset Alzheimer's disease

BACKGROUND

Early-onset Alzheimer's disease (EOAD) has been overshadowed by the more common late-onset AD (LOAD). Yet, the literature indicates EOAD may have less hippocampal-memory presentations and more focal neocortical localization early in the disease.

OBJECTIVE

To evaluate these proposed differences between these 2 forms of AD and to explore what they inform about differences in AD pathophysiology.

METHODS

In all, 21 patients with EOAD and 24 patients with LOAD matched for disease progression and severity were compared on neurocognitive measures and resting state fluorodeoxy-glucose positron-emission tomography (FDG-PET).

RESULTS

Patients with EOAD had worse executive functions with greater hypometabolism in the parietal regions; whereas patients with LOAD had worse confrontation naming and verbal recognition memory with greater hypometabolism in inferior frontotemporal regions.

CONCLUSIONS

In addition to highlighting significant differences between EOAD and LOAD, these results reveal dissociation between executive deficits in AD and frontal hypometabolism, suggesting early disturbances of the parietal-frontal network in EOAD.

Staging Alzheimer's disease progression with multimodality neuroimaging

Rapid developments in medical neuroimaging have made it possible to reconstruct the trajectory of Alzheimer's disease (AD) as it spreads through the living brain. The current review focuses on the progressive signature of brain changes throughout the different stages of AD. We integrate recent findings on changes in cortical gray matter volume, white matter fiber tracts, neuropathological alterations, and brain metabolism assessed with molecular positron emission tomography (PET). Neurofibrillary tangles accumulate first in transentorhinal and cholinergic brain areas, and 4-D maps of cortical volume changes show early progressive temporo-parietal cortical thinning. Findings from diffusion tensor imaging (DTI) for assessment fiber tract integrity show cortical disconnection in corresponding brain networks. Importantly, the developmental trajectory of brain changes is not uniform and may be modulated by several factors such as onset of disease mechanisms, risk-associated and protective genes, converging comorbidity, and individual brain reserve. There is a general agreement between in vivo brain maps of cortical atrophy and amyloid pathology assessed through PET, reminiscent of post mortem histopathology studies that paved the way in the staging of AD. The association between in vivo and post mortem findings will clarify the temporal dynamics of pathophysiological alterations in the development of preclinical AD. This will be important in designing effective treatments that target specific underlying disease AD mechanisms.

Programa de reabilitação neuropsicológica da memória aplicada à demência: um estudo não controlado intrasujeitos

Neste estudo não controlado intrassujeitos, 21 idosos com Alzheimer ou outras demências participaram de um Programa de Reabilitação Neuropsicológica, com oficinas de jardinagem e pistas coloridas. Após o programa, houve aumento nos escores dos seguintes testes: Miniexame do Estado Mental (Z=-1,98, p<0,05); Subteste Verbal de Semelhanças da Escala Wechsler [(Z=-2,09) p<0,05] e Subteste de Aprendizagem de Pares de Fácil Associação para Evocação Tardia da Escala de Memória de Wechsler [(Z=-2,07) p<0,05]. Paralelamente, observou-se redução dos escores de depressão na Escala de Depressão Geriátrica de Yesavage [(Z=-3,02) p<0,00]. Foi demonstrado ainda que essa redução estava associada à aprendizagem de pistas contextuais (reminiscências e sinalizadores) e ao tratamento com anticolinesterásicos administrados por 4 ou 12 semanas [(Z=-2,31) p<0,02]. Ressalta-se, entretanto, que o mesmo não ocorreu com participantes submetidos ao tratamento de 30 semanas [(Z=-2,21) p<0,02].

Increased metabolic vulnerability in early-onset Alzheimer's disease is not related to amyloid burden

Patients with early age-of-onset Alzheimer's disease show more rapid progression, more generalized cognitive deficits and greater cortical atrophy and hypometabolism compared to late-onset patients at a similar disease stage. The biological mechanisms that underlie these differences are not well understood. The purpose of this study was to examine in vivo whether metabolic differences between early-onset and late-onset Alzheimer's disease are associated with differences in the distribution and burden of fibrillar amyloid-beta. Patients meeting criteria for probable Alzheimer's disease (National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's; Disease and Related Disorders Association criteria) were divided based on estimated age at first symptom (less than or greater than 65 years) into early-onset (n = 21, mean age-at-onset 55.2 +/- 5.9 years) and late-onset (n = 18, 72.0 +/- 4.7 years) groups matched for disease duration and severity. Patients underwent positron emission tomography with the amyloid-beta-ligand [(11)C]-labelled Pittsburgh compound-B and the glucose analogue [(18)F]-labelled fluorodeoxyglucose. A group of cognitively normal controls (n = 30, mean age 73.7 +/- 6.4) was studied for comparison. [(11)C]-labelled Pittsburgh compound-B images were analysed using Logan graphical analysis (cerebellar reference) and [(18)F]-labelled fluorodeoxyglucose images were normalized to mean activity in the pons. Group differences in tracer uptake were assessed on a voxel-wise basis using statistical parametric mapping, and by comparing mean values in regions of interest. To account for brain atrophy, analyses were repeated after applying partial volume correction to positron emission tomography data. Compared to normal controls, both early-onset and late-onset Alzheimer's disease patient groups showed increased [(11)C]-labelled Pittsburgh compound-B uptake throughout frontal, parietal and lateral temporal cortices and striatum on voxel-wise and region of interest comparisons (P < 0.05). However, there were no significant differences in regional or global [(11)C]-labelled Pittsburgh compound-B binding between early-onset and late-onset patients. In contrast, early-onset patients showed significantly lower glucose metabolism than late-onset patients in precuneus/posterior cingulate, lateral temporo-parietal and occipital corticies (voxel-wise and region of interest comparisons, P < 0.05). Similar results were found for [(11)C]-labelled Pittsburgh compound-B and [(18)F]-labelled fluorodeoxyglucose using atrophy-corrected data. Age-at-onset correlated positively with glucose metabolism in precuneus, lateral parietal and occipital regions of interest (controlling for age, education and Mini Mental State Exam, P < 0.05), while no correlations were found between age-at-onset and [(11)C]-labelled Pittsburgh compound-B binding. In summary, a comparable burden of fibrillar amyloid-beta was associated with greater posterior cortical hypometabolism in early-onset Alzheimer's disease. Our data are consistent with a model in which both early amyloid-beta accumulation and increased vulnerability to amyloid-beta pathology play critical roles in the pathogenesis of Alzheimer's disease in young patients.

Focal posterior cingulate atrophy in incipient Alzheimer's disease

Severe posterior cingulate cortex hypometabolism is a feature of incipient, sporadic Alzheimer's disease (AD). The aim was to test the hypothesis that this region is focally atrophic in very early disease by studying AD patients at the mild cognitive impairment (MCI) stage, and, if so, to determine whether the amount of atrophy was comparable to that of the hippocampus. Twenty-four patients meeting criteria for amnestic MCI, who all subsequently progressed to fulfil AD criteria, and 28 age-matched controls, were imaged with volumetric MRI. Four regions of interest were manually traced in each hemisphere: two posterior cingulate regions (BA 23 and BA 29/30), the hippocampus (as a positive control) and the anterior cingulate (as a negative control). BA 23 and BA 29/30 were both significantly atrophic and this atrophy was comparable to that found in the hippocampus, in the absence of anterior cingulate cortex (ACC) atrophy. Contrary to previous reports, there was no evidence that posterior cingulate atrophy is specifically associated with early-onset AD. The results indicate that posterior cingulate cortex atrophy is present from the earliest clinical stage of sporadic AD and that this region is as vulnerable to neurodegeneration as the hippocampus.

The topography of grey matter involvement in early and late onset Alzheimer's disease

Clinical observations have suggested that the neuropsychological profile of early and late onset forms of Alzheimer's disease (EOAD and LOAD) differ in that neocortical functions are more affected in the former and learning in the latter, suggesting that they might be different diseases. The aim of this study is to assess the brain structural basis of these observations, and test whether neocortical areas are more heavily affected in EOAD and medial temporal areas in LOAD. Fifteen patients with EOAD and 15 with LOAD (onset before and after age 65; Mini Mental State Examination 19.8, SD 4.0 and 20.7, SD 4.2) were assessed with a neuropsychological battery and high-resolution MRI together with 1:1 age- and sex-matched controls. Cortical atrophy was assessed with cortical pattern matching, and hippocampal atrophy with region-of-interest-based analysis. EOAD patients performed more poorly than LOAD on visuospatial, frontal-executive and learning tests. EOAD patients had the largest atrophy in the occipital [25% grey matter (GM) loss in the left and 24% in the right hemisphere] and parietal lobes (23% loss on both sides), while LOAD patients were remarkably atrophic in the hippocampus (21 and 22% loss). Hippocampal GM loss of EOAD (9 and 16% to the left and right) and occipital (12 and 14%) and parietal (13 and 12%) loss of LOAD patients were less marked. In EOAD, GM loss of 25% or more was mapped to large neocortical areas and affected all lobes, with relative sparing of primary sensory, motor, and visual cortex, and anterior cingulate and orbital cortex. In LOAD, GM loss was diffusely milder (below 15%); losses of 15-20% were confined to temporoparietal and retrosplenial cortex, and reached 25% in restricted areas of the medial temporal lobe and right superior temporal gyrus. These findings indicate that EOAD and LOAD differ in their typical topographic patterns of brain atrophy, suggesting different predisposing or aetiological factors.

Heterogeneity in executive impairment in patients with very mild Alzheimer's disease

BACKGROUND/AIMS

The presence of executive impairment in mild Alzheimer's disease (AD) has primarily been demonstrated by means of group comparison. Whether executive dysfunction is a common feature of mild AD or only present in a subgroup of patients remains unclear. The aim of this study was to describe the frequency of impairment on a set of internationally well-known executive tests in patients with very mild AD.

METHODS

Thirty-six patients with very mild AD (MMSE scores above 23) and 32 healthy control subjects were administered a battery of 7 executive tests: Trail Making part B, Stroop Interference Test, modified Wisconsin Card Sorting Test (WCST), category- and letter-based verbal fluency, a design fluency task and the Similarities subtest from WAIS. Impairment was defined as a score of 2 SD or more below control means.

RESULTS

Executive impairment on at least 1 measure was seen in 76% of the patients, and 50% were impaired on 2 or more tests. Trail Making B and Stroop Interference Test were impaired in more than 40%, whereas only few patients were impaired on Similarities, WCST and design fluency. A wide variation of executive test profiles was seen among the patients.

CONCLUSION

Executive impairments are common in early AD and not just a feature characteristic of a subgroup of patients. Complex attentional skills are more frequently affected than other executive functions. There is, however, considerable heterogeneity among AD patients in the pattern of executive dysfunction.

Molecular neuroimaging in Alzheimer's disease

Considerable data exist to support the use of positron emission tomography (PET) and single photon emission computed tomography (SPECT) scanning as biomarkers for Alzheimer's disease (AD). The techniques are reasonably sensitive and specific in differentiating AD from normal aging, and recent studies with pathological confirmation show good sensitivity and specificity in differentiating AD from other dementias. These techniques also can detect abnormalities in groups of asymptomatic and presymptomatic individuals and may be able to predict decline to dementia. However, there are a number of existing questions related to the use of these techniques in samples that are fully representative of the spectrum of patients with dementia. For example, it is unclear how well PET and SPECT perform in comparison to a clinical diagnosis obtained in the same patient group, when autopsy is used as a gold standard. It will also be important to know what PET and SPECT add to the certainty of diagnosis in addition to the standard clinical diagnosis. Despite these unanswered questions, PET and SPECT may have application as biomarkers for AD in a number of clinical and research settings, especially in academic centers, where most of the existing studies have been done.

Glucose metabolism in early onset versus late onset Alzheimer's disease: an SPM analysis of 120 patients

The aims of this cross-sectional study were (i) to compare the overall glucose metabolism between early onset and late onset Alzheimer's disease in a large sample of patients; and (ii) to investigate the pattern of glucose metabolism as a function of dementia severity in early onset versus late onset Alzheimer's disease, using a statistical parametric mapping (SPM) analysis. Subjects consisted of four groups: 74 patients with early onset Alzheimer's disease, 46 patients with late onset of the disease, and two control groups age matched to each patient group. All the subjects underwent 2-[(18)F]fluoro-2-deoxy-d-glucose (FDG)-PET under the same scanning conditions. Severity of dementia was rated with the Clincial Dementia Rating (CDR). Voxel-based SPM99 was used for statistical analyses. Overall glucose hypometabolism of early onset Alzheimer's disease patients was much greater in magnitude and extent than that of late onset patients, though both groups were similar in dementia severity: the early onset group showed more severe hypometabolism in parietal, frontal and subcortical (basal ganglia and thalamus) areas. When the decline of glucose metabolism was compared as a function of CDR stage, the slope was steeper in early onset than in late onset Alzheimer's disease. The rapid decline occurred at CDR 0.5-1 in the early onset group, whereas similar changes occurred at CDR 2-3 in the late onset group. The greater hypometabolism in early onset than in late onset patients is required to reach the same severity of dementia, probably reflecting greater functional reserve in younger than in older subjects. Alternatively, the metabolic decline curve suggests that the early onset patients may take a more rapid course in the reduction of glucose metabolism than the late onset patients.

Working memory and FDG–PET dissociate early and late onset Alzheimer disease patients

The aims of this study were to determine the influence of the onset of Alzheimer's disease (AD) on 1) memory and cerebral glucose metabolism, 2) the relationships between cognitive performance and cerebral glucose metabolism. Brain metabolism was measured by 18FDG-PET in 12 early onset AD patients (age < 65 years) and 26 late onset ones (> 65), with comparable mean MMSE scores. Working memory, semantic memory and episodic memory were assessed. Cognitivo-metabolic correlations (CMC) and complementary interregional correlations were performed in order to identify specific neurocognitive processes within each group. Both AD groups performed poorly on all tasks, except digit span in the late onset group. The early onset group performed more poorly than the late onset one on both the digit span and Brown-Peterson Paradigm (BPP) tasks. Temporo-parietal hypometabolism was found in both groups, the left hemisphere being more affected than the right, especially in the early onset patients, who also showed specific left frontal hypometabolism. For the BPP task, the CMC principally involved left frontal areas in the early onset group, and the cerebellum in the late onset one. For the digit span task, they involved cerebellar and occipital regions in the latter. Regarding the digit span, the occipital and cerebellar involvement may have reflected an effective compensatory mechanism in the late onset patients, while high left supramarginal gyrus hypometabolism in the early onset patients may have explained their failure in this task. In the BPP task, the lower performance of the early onset group may have been due to a frontal lobe dysfunction, as suggested by 1) the hypometabolism of this region, 2) the CMC results, 3) the interregional correlations, which indicated greater disruption of the antero- posterior loop.

Metabolic interaction between ApoE genotype and onset age in Alzheimer's disease: implications for brain reserve

BACKGROUND

Clinically apparent Alzheimer's disease (AD) is thought to result when brain tissue damage exceeds a critical threshold of "brain reserve", a process possibly accelerated by the apolipoprotein E (ApoE) E4 allele. The interaction between onset age and ApoE genotype was investigated to assess whether early disease onset (<65 years) in patients carrying the E4 allele is associated with greater cerebral metabolic (regional cerebral metabolic rate of glucose utilisation, rCMRgl) reduction.

METHODS

AD patients, divided into early (EOAD; 27 patients) and late onset (LOAD; 65 patients) groups, both groups balanced as to the number of E4 carriers (E4+) and non-carriers (E4-), and matched controls (NC; 35 cases) underwent (18)F-FDG PET ([(18)F]fluorodeoxyglucose positron emission tomography) scanning. SPM'99 software was used to compare AD patients to NC and to perform a two way ANOVA with onset age and ApoE genotype as grouping factors. Results were considered significant at p<0.001, uncorrected.

RESULTS

AD patients demonstrated rCMRgl reductions compared to NC, with rCMRgl lower in association cortex and relatively higher in limbic areas in EOAD compared to LOAD subjects. rCMRgl was lower in the anterior cingulate and frontal cortex for E4+ compared to E4- subjects. A significant onset age by ApoE interaction was detected in the hippocampi and basal frontal cortex, with EOAD E4+ subjects having the greatest rCMRgl reduction.

CONCLUSIONS

The interactive effects of early onset age, possibly reflecting lower brain reserve, and ApoE E4 allele, possibly leading to greater tissue damage, lead to reduced tolerance to the pathophysiological effects of AD in key brain regions.

Neuropsychological performance in early and late onset Alzheimer's disease: comparisons in a memory clinic population

OBJECTIVES

To compare the neuropsychological performance associated with early and late onset Alzheimer's disease (AD), in order to identify differences and compare these with previous reports.

METHODS

Patients attending a memory clinic were given a detailed multi-disciplinary diagnostic assessment, including a battery of neuropsychological tests. From those meeting ICD-10 criteria for Alzheimer's disease (AD), an early-onset (EO) group (n = 40) and a late-onset (LO) group (n = 90) were identified, and their performances compared. Patients with mixed dementia and co-morbid depression were excluded.

RESULTS

After adjustment, the EO and LO groups performed at a comparable level on the majority of the neuropsychological tests. The LO group performed better on the WAIS digit span test, AMIPB Complex Design and the written picture description, and the EO group performed better on the WAIS similarities test and the Boston naming test.

CONCLUSIONS

These findings suggest that, after adjusting for overall dementia severity and pre-morbid IQ, there is greater fronto-parietal/right hemisphere involvement in early-onset AD, and greater temporal/left hemisphere involvement in late-onset AD. This may be due to different genetic risk profiles for AD at different ages.

Alzheimer's disease: differences in technetium-99m HMPAO SPECT scan findings between early onset and late onset dementia

OBJECTIVE

To compare the HMPAO SPECT cerebral perfusion patterns in early and late onset Alzheimer's disease.

METHODS

Twenty patients with early onset disease (<65 years) and 44 patients with late onset disease (>65 years) were studied. All patients fulfilled NINCDS-ADRDA clinical criteria and had details of disease severity and length of history at the time of imaging. Technetium-99m HMPAO SPECT brain scans were acquired on a multi-detector gammacamera and analysed visually and with statistical parametric mapping (SPM99).

RESULTS

Patients with early onset disease had significantly greater posterior cortical association area involvement whereas those with late onset disease had significantly greater medial temporal hypoperfusion. These findings were unchanged after controlling for disease severity and length of illness.

DISCUSSION

These functional imaging findings of the differences between early and late onset Alzheimer's disease are supported by published findings that include histopathological and clinical evidence; namely late onset patients tend to present with the characteristic involvement of the medial temporal lobes producing marked memory loss whereas early onset patients present with predominant posterior cortical association area involvement. These age related findings should be borne in mind when clinically diagnosing, and interpreting functional brain imaging studies in, patients with suspected Alzheimer's disease.

Effect of age on regional cerebral blood flow patterns in Alzheimer's disease patients

The purpose of this study was to explore the influence of age on regional cerebral blood flow (rCBF) patterns in patients with Alzheimer's disease (AD). Single photon emission computed tomography (SPECT) was performed in 79 patients with AD, including 31 younger and 48 older patients divided according to age at examination (<70 and > or = 70 years), and the SPECT data were analyzed using three-dimensional stereotactic surface projection. Although no significant differences in severity and duration of disease between the two groups were found, there were some differences in rCBF patterns. Patients with younger AD had a more severe decrease of rCBF in the parietotemporal and posterior cingulate cortex, while patients with older AD had a more severe decrease of rCBF in the medial temporal region and medial frontal lobe. This observer-independent analysis of SPECT data provides an objective assessment of cortical rCBF abnormalities in patients with AD and is useful in demonstrating the differences in rCBF patterns between younger and older patients with AD.

Differences in cerebral metabolic impairment between early and late onset types of Alzheimer's disease

The purpose of this study was to delineate the specific patterns of cerebral glucose metabolism with regard to the time of onset of Alzheimer's disease (AD).

METHODS

Two groups of 20 AD patients with different ages of onset were examined. The early onset (EO) and late onset (LO) groups had mean ages of onset of 53.9 and 72.7 years. Groups of age-matched normal subjects were used as controls. A regional relative cerebral glucose metabolic image of each subject was obtained by 2-[18F] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET). NEUROSTAT program was used for spatial normalization and voxel-based statistical parametric mapping (SPM) 99 was used for statistical analyses.

RESULTS

Both AD groups had significant hypometabolic regions in the bilateral parieto-temporal regions compared with the age-matched groups. The EO group had more severe hypometabolism in the bilateral parietal and posterior cingulate cortices and precuneus region than the LO group. However, LO group showed no significant hypometabolic regions compared to the EO group.

CONCLUSION

The effects of time of AD onset were delineated as a double dissociation, that is, EO AD patients have a more severe reduction of glucose metabolism. Our finding suggests the existence of biological subtypes of AD.

Relationship between both IQ and Mini-Mental State Examination and the regional cerebral glucose metabolism in clinically diagnosed Alzheimer's disease: a PET study

In order to clarify the hypofunction in which brain areas demonstrate a decline in Intelligence Quotient (IQ), we examined correlations between the IQ and Mini-Mental State Examination (MMSE) and regional cerebral metabolic rate of glucose (rCMRglc) measured using positron emission tomography (PET) in 26 patients with clinically diagnosed Alzheimer's disease (AD). The MMSE scores and full-scale IQ (FSIQ) showed significant correlations with the rCMRglc in the temporal and parietal lobes on both sides and in the left frontal lobe, which were significantly reduced in comparison to those in the normal controls. A multiple regression analysis showed only the MMSE score to predict verbal IQ (VIQ), performance IQ (PIQ) and FSIQ. VIQ was also predicted by the rCMRglc in the left parietal lobe, while PIQ was predicted by the age at onset. The results suggested MMSE to be an index of dementia severity reflected by general intelligence as shown by IQ in AD, and a reduction in the VIQ can thus be used as an index of the left parietal dysfunction, which is not expressed by MMSE.

Measuring the decline of a population of people with early-onset dementia in Lothian, Scotland

OBJECTIVE

To seek differences in the pattern of decline between groups of patients with early-onset dementia of varying aetiologies (clinically defined) on the basis of the investigation of their different clinical profiles.

DESIGN

A cohort of 126 live patients with dementia diagnosed before the age of 65, of various aetiologies, were identified using the Lothian Psychiatric Case Register. Each person was seen for two assessments approximately 1 year apart.

SETTING

Patients were either in long-term care (NHS or other) or at home, usually in the care of relatives.

PATIENTS

Of 126 cases (53 male, 73 female, mean age at referral 58 years), 114 met the diagnostic criteria for DSM-III-R dementia: 60 Alzheimer's type dementia; 13 multi-infarct dementia; 14 alcohol-related dementia; with 25 in a mixed group of overlapping categories and two in 'other' dementia types. By the second assessment, 18 cases had died and two cases refused reassessment.

MEASURES

The data collected included: demographic; behavioural and psychopathological; neurocognitive; neurological; and genetic. Change was assessed.

RESULTS

The alcohol group was distinguished from the other groups by its generally milder profile of impairment and a pattern of change indicating some areas of improvement in the follow-up period.

CONCLUSIONS

There are limitations in the instruments used to measure change in this group of patients; at present, measures of change in dementing illnesses cater predominantly for an elderly population with Alzheimer's disease.

Positron emission tomography for diagnosis of Alzheimer's disease and vascular dementia

In mild or atypical cases of Alzheimer's disease (AD) the differential diagnosis to other dementing diseases, such as vascular dementia (VD), may pose a difficult problem. Beside computed tomography (CT) and magnetic resonance imaging (MRI), functional neuroimaging by positron emission tomography (PET) support the clinical diagnosis by visualizing cerebral function. PET of 18F-2-fluoro-2-deoxy-D-glucose (FDG) for measurement of regional cerebral glucose metabolism (rCMRGl) has shown a typical metabolic pattern in patients with probable AD: hypometabolism in temporoparietal and frontal association areas, but relative recessing of primary cortical areas, basal ganglia and cerebellum. In VD a different pattern is seen. It consists of scattered areas with reduction of rCMRGl typically extending over cortical and subcortical structures. Severity of dementia is correlated with rCMRGl reduction in the temporoparietal association cortex, irrespective of the cause of dementia. Also the total volume of hypometabolic regions is related to severity of dementia but did not differ between AD and VD, even in patients with small lacunar infarction. This indicates that the total volume of functional tissue loss is more important since it also includes the effects of incompletely infarcted tissue and morphologically intact but deafferented cortex. The characteristic metabolic pattern has a high diagnostic accuracy for the discrimination between probable AD, normals and VD, even in patients with mild cognitive impairment. Under clinical and therapeutic aspects the analysis of longitudinal changes of rCMRGl has shown that neuropsychological and metabolic changes are closely related in both, AD and VD.

Age at onset and regional cerebral glucose metabolism in Alzheimer's disease

This study assessed 46 patients with Alzheimer's disease and 21 aged controls using positron emission tomography. Repeated analyses using a general linear model examined the effect of age at onset on the pattern of the regional cerebral metabolic rate of glucose (rCMRglc). The results showed significant age effects on the rCMRglc in the fronto-temporo-parietal association cortices and retrosplenial areas. Disease duration, overall cognitive severity or normal aging could not account for the effects. The age effects were delineated as a double dissociation, that is, early-onset patients have a more severe reduction of regional glucose metabolism in the association cortices, while late-onset patients show a more prominent metabolic deficit in the paralimbic area.

Diagnostic imaging of dementia in the elderly

Dementia is a frequent problem in elderly patients. More than age per se, it may influence the indication for invasive diagnostic and therapeutic procedures to treat other diseases. Here, the role of tomographic imaging methods for differential diagnosis of dementia will be reviewed briefly, with the new possibilities that became available recently. Computed tomography (CT) of the brain is used primarily to detect potentially treatable conditions, such as multiple ischemic infarcts, hematomas, hydrocephalus and brain tumors. It should be performed even at higher age if the general condition of the patient is good enough not to exclude all specific therapeutic measures. Magnetic resonance imaging (MRI) is more sensitive for ischemic white matter lesions and hippocampal atrophy and should therefore used preferentially in mildly affected patients. Functional imaging methods, such as single photon emission computed tomography (SPECT) and positron emission tomography (PET), are necessary only in clinically unclear cases to demonstrate functional impairment of association cortex.

Decreased expression of nuclear and mitochondrial DNA-encoded genes of oxidative phosphorylation in association neocortex in Alzheimer disease

We recently reported 50% decreases in mRNA levels of mitochondrial DNA (mtDNA)-encoded cytochrome oxidase (COX) subunits I and III in Alzheimer disease (AD) brains. The decreases were observed in an association neocortical region (midtemporal cortex) affected in AD, but not in the primary motor cortex unaffected in AD. To investigate whether the decreases are specific to mtDNA-encoded mRNA, we extended this analysis to nuclear DNA (nDNA)-encoded subunits of mitochondrial enzymes of oxidative phosphorylation (OXPHOS). Brains from five AD patients showed 50-60% decreases in mRNA levels of nDNA-encoded subunit IV of COX and the beta-subunit of the F0F1-ATP synthase in midtemporal cortex compared with mRNA levels from midtemporal cortex of control brains. In contrast, these mRNAs were not reduced in primary motor cortices of the AD brains. The amount of nDNA-encoded beta-actin mRNA and the amount of 28S rRNA were not altered in either region of the AD brain. The results suggest that coordinated decreases in expression of mitochondrial and nuclear genes occur in association cortex of AD brains and are a consequence of reduced neuronal activity and downregulation of OXPHOS machinery.

Mapping histology to metabolism: coregistration of stained whole-brain sections to premortem PET in Alzheimer's disease

The association between [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) counts obtained 8 h before death and neurofibrillary tangle (NFT) staining density in a patient with Alzheimer's disease (AD) was evaluated. In our patient FDG-PET counts were globally decreased with a greater focal deficit in the left medial temporal region independent of volume loss. After death, whole-brain sections derived from cryomacrotome sectioning were stained for NFTs by the Gallyas method and elastically warped into their native space enabling registration with premortem FDG-PET data. Gallyas staining density was localized to the paralimbic cortex of the basal forebrain, medial temporal, and orbital frontal regions. The poor correlation between NFT staining density and hypometabolism on FDG-PET implicates alternate mechanisms underlying the metabolic defect in AD.

Patterns of neuropsychological impairment in dementia of the Alzheimer type and multi-infarct dementia

Patterns of performance on 22 neuropsychological tests were examined in 58 patients with presumed dementia of the Alzheimer type (DAT) and 58 patients with presumed multi-infarct dementia (MID). Few differences between patterns of performance in DAT and MID were found when overall level of performance was taken into account. Within the DAT group, there were some age-related differences in performance that in themselves might support other studies suggesting clinical and neuropathological differences between subtypes of DAT that are related in part to the age at which the condition occurs. However, similar age-related patterns were found in the MID group and the DAT and MID groups did not differ significantly in this respect. Considerable inter-individual variability in pattern of performance was apparent within each group. A proportion of patients were re-assessed 10 months after initial assessment: the extent of decline over time was not predictable from patients' characteristics or test performances at initial assessment. 'De-differentiation' in patterns of impairment, over time or with increasing severity of impairment, was not observed.

Neurotrophins and Alzheimer's disease: beyond the cholinergic neurons

Improvement of the cholinergic deficit in Alzheimer's disease (AD) by intracerebral application of nerve growth factor (NGF) serves as a paradigmatic example for a novel approach to the treatment of neurodegeneration. The first part of this paper presents and discusses experiments which were performed in our laboratory to study the NGF receptor response after intracerebral NGF treatment in vivo. We found that intraparenchymal NGF elicits prolonged tyrosine phosphorylation of Trk type NGF receptors. Our results indicate that intraparenchymal injections are preferable to intraventricular application for targeting specific neuronal populations with minimal side effects. Besides the cholinergic deficit, severely disturbed brain energy metabolism, particularly in cortical association areas, is another consistent feature of AD. Metabolic hypofunction is observed early in the disease progression and correlates with the cognitive impairment. Cell culture findings are presented which indicate that brain-derived neurotrophic factor (BDNF), and other neurotrophins with activity on the TrkB tyrosine kinase receptor, increase mRNA levels and biochemical activity of enzymes of the glycolytic pathway in brain cells. Treatment with these factors was also found to stimulate glucose utilization in rat embryonic cortex cells in primary cultures. Our observations suggest that selected neurotrophins should become useful not only for the treatment of the cholinergic deficit in AD, but also of the cortical metabolic hypofunction associated with this disease.

Everyday functioning in Alzheimer's disease: contribution of neuropsychological testing

COGNITIVE AND BEHAVIORAL problems associated with Alzheimer's disease are variable and complex; consequently, each patient should be managed by an advanced practice nurse (APN) so that everyday functioning is maximized and excess disabilities are prevented. Neuropsychological testing is sensitive to neuropathological conditions and holds promise for assisting APNs in the care of the Alzheimer's patient by pinpointing areas of cognitive and behavioral impairment. In this article, an overview is given of the essentials of a neuropsychological assessment for the Alzheimer's patient as performed by the neuropsychologist. Use of assessment results by the APN for designing interventions that compensate for losses but which preserve remaining abilities is discussed.

A single photon emission computed tomography study of cerebral regional perfusion changes induced by a learning task in subjects with mild memory impairment

Fifteen nondemented subjects with memory complaints underwent serial single photon emission computed tomography (SPECT) studies with technetium-99m-d, l-hexamethyl-propylene amine oxime (HMPAO) as tracer. Scans were carried out under a baseline conditions and during the learning phase of the Memory Efficiency Profile (MEP), a combined visual perception and memory task developed by Rey. Results indicate a positive correlation between activation, as indexed by HMPAO uptake, and neuropsychological assessment. Right temporal activation was correlated with MEP immediate recall. The right cerebellum was correlated with both MEP immediate and delayed recall. This study suggests that SPECT can show cortical activation during cognitive performance in subjects with mild memory impairment.

Impairment in mitochondrial cytochrome oxidase gene expression in Alzheimer disease

Brains from 5 patients with Alzheimer's disease (AD) showed a 50%-65% decrease in mRNA levels of the mitochondrial-encoded cytochrome oxidase (COX, a marker of oxidative metabolism) subunits I and III in the middle temporal association neocortex, but not in the primary motor cortex, as compared to 5 control brains. The amount of mitochondrial-encoded 12S rRNA was not altered, nor was the amount of nuclear-encoded lactate dehydrogenase B mRNA (a marker of glycolytic metabolism). These data suggest that the decrease in COX I and III subunits mRNA in affected brain regions may contribute to reduced brain oxidative metabolism in AD.

Difference of regional cerebral metabolic pattern between presenile and senile dementia of the Alzheimer type: a factor analytic study

Positron emission tomographic studies using metabolic ratios to represent the contrast between certain brain regions have shown differences of cerebral glucose metabolism between presenile and senile dementia of Alzheimer type (DAT). In this study, factors for regional variance of cerebral metabolism in 61 patients with probable Alzheimer's disease were obtained using principal component analysis (PCA). The difference between two age groups of DAT patients according to age at onset < or = 65 years (n = 30) and > 65 years (n = 31) were investigated. A PCA using nine pairs of cerebral regions normalized to cerebellum for reduction of intersubject variability identified five regional factors for cerebral metabolism: one each for the left and right temporo-parietal cortex, and the other three for frontal cortex, primary visual and sensorimotor cortex, and mesial temporal sensorimotor cortex, and mesial temporal cortex. The age groups differed significantly only in the factor for the right temporo-parietal cortex, with a more prominent metabolic reduction in presenile than senile DAT. Severity of dementia was correlated with the factors for the right and left temporo-parietal cortex. The effect of age at onset on glucose metabolism of the right temporo-parietal cortex was independent from that of dementia severity in DAT.

The cortical topography of temporal lobe hypometabolism in early Alzheimer's disease

Alzheimer's disease (AD) is characterized by a pathological process with specific predilection for association neocortex and the mesial temporal lobes. Recently developed high-resolution positron emission tomographs (PET) are able to quantitate regional cerebral metabolic rates for glucose (rCMRglc) in these brain regions and map the distribution of the metabolic consequences of Alzheimer pathology. In order to evaluate the relative involvement of mesial and neocortical temporal lobe brain regions in AD, we studied 22 AD patients, 11 of whom were mildly demented and 11 of whom were moderately demented in comparison to 8 age-matched control subjects. We used a PET instrument with 2.6 mm in-plane resolution and quantitated rCMRglc in anterior, middle, and posterior temporal neocortex, visual association cortex, primary visual cortex, and mesial temporal cortex. Although the moderately demented AD patients showed significantly lower metabolic rates than controls in visual association cortex and all temporal lobe regions except right anterior temporal neocortex, the mildly demented patients were different from the controls in only middle temporal neocortex. Considerable variability was found in the relative involvement of mesial temporal lobes and temporal neocortex in the AD patients, however, as shown by greater variance of a ratio of mesial temporal lobe rCMRglc to temporal neocortical rCMRglc (MES/NEO ratio) in the AD patients than the controls. A series of stepwise multiple regressions showed that this ratio was related to patient cognitive symptomatology, with more severely memory-impaired patients showing lower MES/NEO ratios, while patients with visuospatial disturbances showed higher MES/NEO ratios. In addition, the only biological variable that was related to this ratio was patient age, with older patients showing lower MES/NEO ratios. These results indicate that mesial temporal lobe structures are not invariably the earliest nor the most severely metabolically involved brain regions in AD and that the relative involvement of the mesial and neocortical temporal lobe is related to the patient's cognitive symptoms and age.

Symptom progression in Alzheimer's disease: relation to onset age and familial aggregation. Results of a longitudinal study

We investigated the hypotheses that symptom progression in Alzheimer's disease is related to onset age and familial aggregation. In a psychiatric outpatient clinic we examined a cohort of 265 consecutively admitted patients 90 of which were diagnosed mild to moderate Alzheimer's disease according to the ICD-10 research criteria. Within twelve months follow-up 73 cases of these 90 patients were investigated twice. We found that early onset cases compared to late onset cases as well as patients with a familial aggregation compared to patients without such an aggregation were no different with respect to the rate of symptom progression in Alzheimer's disease. Furthermore, the hypothesis that early onset cases with a familial aggregation more rapidly deteriorate cognitively compared to late onset cases without such an aggregation could not be confirmed. Our results suggest that the large interindividual variation of symptom progression in Alzheimer's disease cannot be explained by onset age and familial aggregation.