Alzheimer's disease: clinical course and cognitive disturbances

The ICTUS Study: A Prospective Longitudinal Observational Study of 1,380 AD Patients in Europe

The long-term objective of the ICTUS study is to identify milestones in Alzheimer's disease (AD) progression and to develop a model to predict disease course in individual AD patients in Europe. The secondary objectives are to describe the patterns of prescribing, and the socioeconomic impact of AD in Europe. Between 2003 and 2005 1,380 patients with probable AD were recruited in specialised (secondary care) clinics in 12 European countries. Their mean age was 76 years and they had a mean of 8.0 +/- (SD) 4.6 years of education. Thirty-five percent were male. The mean MMSE score was 20.4 +/- (SD) 4.0. Forty-three percent had very mild dementia (CDR 0.5) and 44% had mild dementia (CDR 1). All patients completed baseline evaluation and biannual follow-up is ongoing. The goals of the current study are to describe the specific methods for recruitment in this crosscultural setting and the characteristics of the inception ICTUS cohort, including clinical features, co-morbidity, neuropsychological performance, neuropsychiatric symptoms, functional impairment and social burden.

Dementia and mortality in persons with Down's syndrome

BACKGROUND

Numerous studies have documented that persons with Down's syndrome (DS) are at an increased risk of Alzheimer's disease (AD). However, at present it is still not clear whether or not all persons with DS will develop dementia as they reach old age.

METHODS

We studied 506 people with DS, aged 45 years and above. A standardized assessment of cognitive, functional and physical status was repeated annually. If deterioration occurred, the patients were examined and the differential diagnosis of dementia was made according to the revised Dutch consensus protocol and according to the ICD-10 Symptom Checklist for Mental Disorders. We compared our findings with those reported in the literature.

RESULTS

The overall prevalence of dementia was 16.8%. Up to the age of 60, the prevalence of dementia doubled with each 5-year interval. Up to the age of 49, the prevalence is 8.9%, from 50 to 54, it is 17.7%, and from 55 to 59, it is 32.1%. In the age category of 60 and above, there is a small decrease in prevalence of dementia to 25.6%. The lack of increase after the age of 60 may be explained by the increased mortality among elderly demented DS patients (44.4%) in comparison with non-demented patients (10.7%) who we observed during a 3.3-year follow-up. There was no decrease in incidence of dementia in the age group of 60 and above. Our findings are very similar to those published in the literature. Patients with dementia were more frequently treated with antiepileptic, antipsychotic and antidepressant drugs. The history of depression was strongly associated with dementia.

CONCLUSIONS

Our study is one of the largest population-based studies to date. We found that despite the exponential increase in prevalence with age, the prevalence of dementia in the oldest persons with DS was not higher than 25.6%.

Improved detection of auditory P3 abnormality in dementia using a variety of stimuli

The purpose of this study was to test the improved sensitivity of P3 abnormality in the detection of dementia using a variety of auditory stimuli. Improved detection was obtained using auditory stimuli that differed in their cognitive attributes and by using several P3 measures. These measures included P3 latencies and amplitudes relative to pure tone evoked P3s. Fourteen demented patients (mean age 79.2 years) and a matched normative group were tested. Abnormality of P3 latency for pure tone targets was found in ten patients, equivalent to a hit-rate of 72%. The hit-rate could be further increased by using phonemically and phonetically different types of auditory stimuli, thought to vary in their cognitive attributes. These findings underscore the importance of using a variety of stimuli in testing demented patients.

Reduced temporal lobe blood flow in Alzheimer's disease

We used single photon emission computed tomography with the blood flow tracer [123I]N-isopropyl-p-iodoamphetamine (IMP) to study regional cerebral blood flow (rCBF) in 50 mildly and moderately demented Alzheimer's disease (AD) patients to evaluate rCBF as a function of disease severity. Relative rCBF (normalized to occipital cortex) was significantly lower than controls in temporal cortex for both mildly and moderately demented patients. Similar numbers of patients in both groups demonstrated perfusion abnormalities in temporal neocortex. Parietal cortex was more variably involved with greater numbers of moderately than mildly demented patients showing perfusion abnormalities. Relative rCBF in dirsolateral frontal cortex was reduced only in the moderately demented patients. Disease severity, as measured by the Mini Mental Status Examination, was associated with relative rCBF only in dorsolateral frontal and parietal cortex. These results suggest that the temporal lobes are the first neocortical regions affected by AD and that other cortical areas become involved as the disease progresses.

Development of an "early" detection battery for dementia of the Alzheimer type

1. To develop a diagnostic battery sensitive to and specific for the early detection of Alzheimer disease (AD) dementia, the authors reviewed over 400 journal articles dealing with the diagnosis of A.D. or senile dementia and cognitive assessment in organic brain dysfunction and closed head injury. 2. We culled those studies that met our criteria for solid, reliable and statistically significant results and recommend the testing paradigms that most often produced good discrimination of mild AD dementia from normal senescence. 3. These include tests of language, verbal and non-verbal memory, perception, praxis, attention and reasoning. 4. The battery we assembled takes less than 1 hour to administer, requires no special equipment, and was designed as an early screen for use by psychologists, psychiatrists and other trained health care professionals; it is not intended for repeated administration, as in pharmacological or longitudinal studies.

Red cell superoxide dismutase, glutathione peroxidase and catalase in Down syndrome patients with and without manifestations of Alzheimer disease

The activities of red blood cell enzymes that scavenge the superoxide radical and hydrogen peroxide were measured in severely to profoundly retarded adult Down syndrome (DS) patients with and without manifestations of Alzheimer disease (AD), and control individuals matched for sex, age, and time of blood sampling. Cu,Zn superoxide dismutase (SOD-1) and glutathione peroxidase (GSHPx) activities were significantly elevated (1.39-fold and 1.24-fold, respectively) in DS individuals without AD. When an adjustment was made for the SOD gene dosage effect, DS patients with AD manifestations had significantly lower SOD levels than the matched control individuals. In contrast, DS patients with and without AD had a similar elevation in GSHPx (an adaptive phenomenon). The mean catalase (CAT) activity was no different in DS and control individuals; however, in a paired regression analysis, DS patients without AD had marginally lower CAT activity than control individuals, whereas DS patients with AD had slightly but not significantly higher CAT activity. Thus, AD manifestations in this DS population are associated with changes in the red cell oxygen scavenging processes.

Mild senile dementia of the Alzheimer type: 2. Longitudinal assessment

Forty-three subjects with mild senile dementia of the Alzheimer type (SDAT, so-called probable Alzheimer's disease) were studied longitudinally by serial administration of several tests to rate dementia. Comparison was made with 58 healthy elderly controls. The clinical diagnosis was confirmed in all 16 autopsies. At 5 years after entry into the study, the cumulative rate of nursing home placement was 73%, and of death, 30%, rising at 7 years to 84% and 44%, respectively. Four of six clinical measures of dementia were found to correlate with the natural history of SDAT. Several measures are better than a single one in carrying out longitudinal studies of the disorder.

Aluminum and Alzheimer's disease: perspectives for a cytoskeletal mechanism

A considerable volume of literature has accumulated concerning the association of aluminum with Alzheimer's disease. The pathogenic mechanisms resulting in Alzheimer's disease remain unknown, but recent investigations have focused on cytoskeletal abnormalities as perhaps the key lesion in Alzheimer's disease and related neurological disorders. The diversity of neuronal functions that are dependent on cytoskeletal integrity suggests that subtle effects on polymerization, assembly, transcription, or processing of cytoskeletal elements may have significant and far-reaching neurological effects. That aluminum may participate in the development of neuropathological lesions characteristic of Alzheimer's disease is suggested by evidence that aluminum is a potent cytoskeletal toxin, produces cognitive deficits in laboratory animals, and can be detected within abnormal neurons isolated from brain tissue from Alzheimer's disease patients. In this review, a critical look will be taken at the enigmatic role aluminum has played in Alzheimer's disease research, the possibility of its pathogenicity, and its use as a tool for the investigation of cytoskeletal changes that may result in the biochemical and, ultimately, clinical manifestations of Alzheimer's disease.