Biomedical subjects

O Almkvist

Publications and source records attributed to O Almkvist.

67 records · Page 4Linked to original sources

PubMedDate not supplied

Skin vessel reactivity is impaired in Alzheimer's disease.

Fifteen patients with Alzheimer's disease (AD) and 16 age-matched controls underwent skin vessel reactivity tests employing three vasodilating substances with different modes of action: acetylcholine (ACh), nitroprusside, and isoprenaline. The substances were iontophoresed into the skin and the results were mapped through a newly developed laser Doppler perfusion imager. The skin vascular responses of the patients to ACh and isoprenaline but not nitroprusside were significantly attenuated compared to those of the controls. The differences between patient and control groups concerning skin vessel reactivity might be due to receptor/signal transduction abnormalities but might in addition indicate an attenuated endothelium-dependent vasodilation in AD. The results of this study support the hypothesis that AD might be a systemic disease. They suggest that tests of skin vessel reactivity might be of help in the antemortem diagnosis of AD.

Acetylcholine↗

PubMedDate not supplied

Quantitative electroencephalography in mild cognitive impairment: longitudinal changes and possible prediction of Alzheimer's disease.

The present study evaluated the clinical course of patients with mild cognitive impairment (MCI), the pattern of electroencephalography (EEG) changes following cognitive deterioration, as well as the potential of neurophysiological measures in predicting dementia. Twenty-seven subjects with MCI were followed for a mean follow up period of 21 months. Fourteen subjects (52%) progressed (P MCI) to clinically manifest Alzheimer's disease (AD), and 13 (48%) remained stable (S MCI). The two MCI subgroups did not differ in baseline EEG measures between each other and the healthy controls (n = 16), but had significantly lower theta relative power at left temporal, temporo-occipital, centro-parietal, and right temporo-occipital derivation when compared to the reference AD group (n = 15). The P MCI baseline alpha band temporo-parietal coherence, alpha relative power values at left temporal and temporo-occipital derivations, theta relative power values at frontal derivations, and the mean frequency at centro-parietal and temporo-occipital derivations overlapped with those for AD and control groups. After the follow-up, the P MCI patients had significantly higher theta relative power and lower beta relative power and mean frequency at the temporal and temporo-occipital derivations. A logistic regression model of baseline EEG values adjusted for baseline Mini-Mental Test Examination showed that the important predictors were alpha and theta relative power and mean frequency from left temporo-occipital derivation (T5-O1), which classified 85% of MCI subjects correctly.

Adult↗

PubMedDate not supplied

Sleep disturbances and exposure to organic solvents.

An inquiry about sleep habits and sleep disturbances revealed a significantly higher prevalence of insomnia in a solvent-exposed group than in a comparable group that had no occupational exposure to organic solvents. In the solvent-exposed group was also registered an increased consumption of hypnotics, and a significant increase occurred in the number of individuals who had consulted physicians because of sleep disorders. The results indicate that solvent exposure could induce sleep disturbance.

Asbestos↗

PubMedDate not supplied

Cognitive and behavioral differentiation of frontal lobe degeneration of the non-Alzheimer type and Alzheimer's disease.

Neuropsychological differences between 14 patients with a clinical diagnosis of frontal lobe degeneration of non-Alzheimer type (FLD) and 15 patients with a clinical diagnosis of Alzheimer's disease (AD) were studied. The most efficient psychometric predictors of FLD were Digit Symbol, estimation tasks, word list recall, and particularly the FAS word fluency test. Behavioral predictors of FLD and AD showed a double dissociation: regression and impulsivity characterized FLD, whereas lack of motivation and slowness were typical of AD. Cognitive and behavioral differences between groups were not related to the degree of dementia, as measured by Mini Mental State Examination, indicating that differences remained during progression of the diseases.

Affective Symptoms↗

PubMedDate not supplied

Impairment of neocortical metabolism predicts progression in Alzheimer's disease.

Progression rates of Alzheimer's disease (AD) vary considerably, and they are particularly difficult to predict in patients with mild cognitive impairment. We performed a prospective multicenter cohort study in 186 patients with possible or probable AD, mostly with presenile onset. In a cross-sectional analysis at entry, impairment of glucose metabolism in temporoparietal or frontal association areas measured with positron emission tomography was significantly associated with dementia severity, clinical classification as possible versus probable AD, presence of multiple cognitive deficits and history of progression. A prospective longitudinal analysis showed a significant association between initial metabolic impairment and subsequent clinical deterioration. In patients with mild cognitive deficits at entry, the risk of deterioration was up to 4.7 times higher if the metabolism was severely impaired than with mild or absent metabolic impairment. Copyrightz1999S.KargerAG, Basel

Aged↗

PubMedDate not supplied

A follow-up study of the family with the Swedish APP 670/671 Alzheimer's disease mutation.

OBJECTIVE: To study the progression of Alzheimer's disease (AD) at a very early stage and to evaluate clinical markers of presymptomatic AD. SETTING: Longitudinal study at a university hospital. SUBJECTS: A Swedish family harboring a double mutation at codons 670/671 of the APP gene on chromosome 21 was followed longitudinally for 3 years. Both mutation carriers and noncarriers participated. OUTCOME MEASUREMENTS: Results from clinical investigations, electroencephalography, neuropsychological and neuroradiological examinations including magnetic resonance imaging, single-photon emission computed tomography and positron emission tomography were assessed and compared on two or more occasions. MAIN OUTCOME: During follow-up, 1 initially asymptomatic mutation carrier who was near the expected age of onset for this family, developed cognitive symptoms, and at the end of the follow-up fulfilled the diagnostic criteria for AD. One mutation carrier with cognitive symptoms at the first examination showed clinical deterioration and was diagnosed with AD. One demented mutation carrier died and was shown to have typical AD neuropathology at autopsy. The two remaining asymptomatic mutation carriers, as well as all the noncarriers were asymptomatic. These mutation carriers who were near the expected age of onset of AD but without clinical signs of the disease, did not show changes in either electrophysiological parameters or volumes of the temporal lobes. However, in these 2 individuals the blood flow in the temporal lobe showed intermediate values between the symptomatic mutation carriers and healthy noncarriers. Two neuropsychological tests showed a deterioration that paralleled clinical symptoms in 1 of the mutation carriers who was close to the expected age of onset and who at the end of the follow-up had clinical signs of AD. In the same subject, brain glucose metabolism was pathologically reduced in the temporal lobes before other clinical symptoms were obvious. CONCLUSION: In this familial form of AD a reduced temporal lobe glucose metabolism was indicative of AD before the expected clinical onset. Reduced glucose metabolism even preceded the development of subjective or objective cognitive dysfunction and might therefore serve as a clinical marker for AD before the onset of clinical symptoms. Reduced cerebral blood flow in the temporal lobes and cognitive deterioration paralleled the clinical decline in the early stage of the disease. Copyrightz1999S.KargerAG,Basel

Adult↗

PubMedDate not supplied

First symptoms--frontotemporal dementia versus Alzheimer's disease.

Frontotemporal dementia (FTD) is often misdiagnosed as Alzheimer's disease (AD). We hypothesized that the first symptoms associated with FTD would be different from those seen in AD and that the first symptoms in FTD would reflect loss of function in the frontal region with the greatest degree of degeneration. The objective of the study was to compare the earliest symptoms in patients with FTD and AD, and to delineate the symptoms that were associated with right, left or bilateral frontotemporal degeneration in FTD. The first symptoms in 52 FTD and 101 AD patients were determined in retrospect. Based on functional imaging studies, the FTD patients were divided into those with predominantly bilateral (n = 15), left-sided (n = 19) and right-sided (n = 18) patterns of atrophy. The results showed that disinhibition, social awkwardness, passivity and loss of executive function were more common in FTD, while memory loss was more common in AD. Disinhibition was greatest in the asymmetric right-sided group, language dysfunction was commonest in the asymmetric left-sided group and loss of executive function was most frequent in the bilateral group. In summary, different first symptoms appeared in FTD and AD, which may help distinguish between the diseases. The anatomic site for FTD largely determined the kind of first symptoms.

Aged↗

PubMedDate not supplied

Responder characteristics to a single oral dose of cholinesterase inhibitor: a double-blind placebo-controlled study with tacrine in Alzheimer patients.

A proportion of Alzheimer's disease (AD) patients treated for several months with cholinesterase (ChE) inhibitors have shown some favorable response on cognition, but the characteristics of the responders are still unclear. This study attempts to identify the characteristics of individuals with a positive behavioral response after a double-blind randomized administration of a single oral dose of tacrine (40 mg) and placebo to AD patients. Furthermore, the relationship between single-dose and long-term responders are examined. Twenty-four mildly to very mildly demented AD patients participated in the study. They all fulfilled the diagnosis of probable AD according to NINCDS-ADRDA criteria. Active treatment (tacrine 40 mg) and placebo was administered in random order on 2 consecutive days, and the effects were evaluated within 2 h using neuropsychological tests (assessing visuospatial ability, episodic memory and attention), registration of EEG activity and measurement of red blood cells (RBC) acetylcholinesterase (AChE), ChE activity and concentrations of tacrine and its metabolites in plasma. Results demonstrated significant improvement, tacrine compared to placebo, in measures of attention, but not in episodic memory or visuospatial ability. A single-dose response was therefore defined in terms of improvement in attention. The tacrine plasma concentration (pcTHA) showed a positively skewed distribution (mean +/- SD: 10.5 +/- 11.8, range: 1.0-51.8 ng/ml). There were no significant differences between single-dose responders compared to nonresponders in pcTHA, metabolites of tacrine, inhibition of AChE in RBC, tau levels in CSF, AChE activity in CSF or plasma and demographic variables. However, single-dose responders showed a higher right frontal alpha/theta ratio on EEG and had lower glucose metabolism in the parietal-temporal association cortex at baseline. In addition, the frequency of apolipoprotein E (APOE) epsilon 4 alleles was higher in responders. Interestingly, the single-dose response was related to the long-term response, although not significantly, which probably was due to lack of power. To conclude, the present study identified single-dose responders in terms of improved attentional performance associated with a relatively higher alpha/theta activity in the right frontal regions of the brain measured on EEG and predominance of APOE epsilon 4 allele.

Acetylcholine↗

PubMedDate not supplied

White matter lesions impair initiation of FAS flow.

Word fluency performance is known to rely on left frontal cortical regions and has also been shown to be affected by lesions in the white matter, which may be seen as white matter hyperintensities (WMH) on magnetic resonance imaging. However, word fluency may be divided into two independent components, initial and late performance, separated in time [J Clin Exp Neuropsychol 1998;20:137-143]. The purpose of the current study was to investigate the relationship between the two components of FAS fluency performance and WMH. Patients varying in degree of memory impairment participated: Alzheimer's disease, mild cognitive impairment and subjective memory disorder. WMH were rated with the Scheltens scale in the periventricular and deep subcortical areas. Results demonstrated that WMH in this sample of patients may be summarized in two indices according to a principal factor analysis, one anterior factor mainly related to WMH in the frontal lobes and adjacent to ventricles, and a second posterior factor related to parietal and occipital WMH. The initial FAS performance was related to anterior WMH, in particular left frontal or lateral periventricular hyperintensities, whereas the late FAS performance was not related to any index of WMH.

Aged↗

PubMedDate not supplied

Tone duration discrimination in demented, memory-impaired, and healthy elderly.

In order to assess the diagnostic validity of a new test of tone duration discrimination (TDD), we tested elderly subjects, 32 Alzheimer-type (AD) and 11 vascular-type dementia (VAD) patients, 11 memory-impaired (MI), and 21 healthy controls with a TDD test as well as with 18 standard neuropsychological (NP) tests. The TDD test efficiently discriminated demented patients from MI, and MI from controls. As an index of cognitive impairment, the TDD test was sensitive also in comparison to NP tests. This suggests that processing of auditory duration information is impaired in dementia as well as in MI. Patients suffering from AD and VAD differed in that the VAD but not the AD patients improved their TDD performance when the interstimulus interval was lengthened. This shows that the processing of auditory temporary information involves functions sensitive to dementia diseases as well as to MI. The TDD test could add discriminatory power in diagnosis and differential diagnosis of dementia.

Aged↗

PubMedDate not supplied

Global dimensional complexity of multichannel EEG in mild Alzheimer's disease and age-matched cohorts.

Multichannel EEG as sequence of momentary brain field maps constitutes a trajectory through K-dimensional state space (K = number of channels); the complexity of this trajectory is assessed by the nonlinear measure of global correlation dimension (Global Dimensional Complexity, GDC) with the number of electrodes as embedding dimension. We analyzed eyes-closed EEG of three age-matched subject groups: mild Alzheimer's disease (AD; n = 21), mild cognitive impairment (29) and subjective memory complaint (29). Kruskal-Wallis statistics showed an overall effect between groups. AD patients differed significantly (GDC = 4.56) from mild cognitive impairments (GDC = 4.98) and from subjective memory complaints (GDC = 4.93). GDC also had significant positive correlations with mental condition and performance (MMSE and WAIS-R scores). Thus, the dynamics of brain state development over time in mild AD differs from that in mild cognitive impairment and in subjective memory complaint cases.

Aged↗

PubMedDate not supplied

Neuropsychological deficits in vascular dementia in relation to Alzheimer's disease: reviewing evidence for functional similarity or divergence.

The hypothesis that vascular dementia (VAD) may be associated with a specific pattern of neuropsychological dysfunction as compared to Alzheimer's disease (AD) is reviewed. The empirical findings were evaluated with regard to methodology, most importantly the comparability between groups regarding demographic variables and severity of dementia. They were also classified according to the cognitive and sensory-motor functions affected. No consistent differences were found between VAD and AD patients in neuropsychological performance testing general cognitive functioning, syntax, verbal comprehension, visuospatial tasks, and primary as well as semantic memory, indicating a functional similarity between VAD and AD. However, inferior performance was found for VAD in executive functioning, verbal fluency, attention, and motor performance. Superior performance for VAD was found in naming and with regard to intrusion errors. The findings on episodic memory were inconclusive. These results should be considered in light of possible selection bias due to the fact that all studies used a hospital-based sample of subjects and not subjects from the community. Bias may also arise from the variations in lesion site, size, number, and timing between different VAD groups. Third, the risk of confounding errors due to a lack of comparability between etiological groups in terms of demographic variables as well as cognitive decline cannot be excluded. Future studies should take into account variation in the severity of cognitive decline, variation regarding lesion characteristics, etiological factors, and subtypes of VAD in order to increase our knowledge about the functional features of VAD.

Aged↗

PubMedDate not supplied

Quantitative electroencephalography power and coherence in Alzheimer's disease and mild cognitive impairment.

In this study the best combination of quantitative electroencephalographic variables (qEEG) for the discrimination of groups with mild to moderate Alzheimer's disease (AD), mild cognitive impairment and healthy subjects was defined and related to neuropsychological performance. The study population included 18 patients with mild to moderate probable AD, 19 subjects with objective memory disturbance, 17 subjects with subjective memory complaints who did not have clinical evidence of memory disturbance, and 16 healthy controls. AD patients had significantly increased theta and decreased alpha relative power, mean frequency, and temporoparietal coherence. There was no significant difference in the mean frequency in the left temporal region between AD patients and subjects with objective memory disturbances. Temporoparietal coherence appeared as a discriminant variable together with alpha and theta relative power only between AD patients and controls giving 77.8% sensitivity and 100% specificity. Significant correlations between regional changes in qEEG variables and cognitive functions were found.

Aged↗