W.A. van Gool

Visual assessment of medial temporal lobe atrophy on magnetic resonance imaging: interobserver reliability

We conducted an interobserver study to assess agreement on visual rating of medial temporal lobe atrophy on coronal T1-weighted MRI. A total of 100 studies of elderly individuals, using two different MRI techniques (spin echo and inversion recovery sequences), were analysed by four raters (three neurologists and one neuroradiologist) using a five-point rating scale. Complete agreement was found in 37% of the total sample. Interobserver agreement as expressed by kappa values was 0.44 (95% CIl0.34–0.54) and 0.51 (95% Cl=0.41–0.61) for the two techniques. After dichotomizing medial temporal lobe atrophy into present or absent, a post hoc analysis revealed higher complete agreeement (70%), with kappa values of 0.59 (95% Cl=0.51–0.67) and 0.62 (95% Cl=0.48–0.075), for the two techniques (all four raters). From this study we conclude that visual rating of medial temporal lobe atrophy on MRI in the coronal plane yields fair to good agreement among observers. We recommend this type of visual rating for use in clinical settings when a quick judgement on the presence of medial temporal lobe atrophy is needed.

The significance of neuroinflammation in understanding Alzheimer’s disease

Summary.The interest of scientists in the involvement of inflammation-related mechanisms in the pathogenesis of Alzheimer’s disease (AD) goes back to the work of one of the pioneers of the study of this disease. About hundred years ago Oskar Fischer stated that the crucial step in the plaque formation is the extracellular deposition of a foreign substance that provokes an inflammatory reaction followed by a regenerative response of the surrounding nerve fibers. Eighty years later immunohistochemical studies revealed that amyloid plaques are indeed co-localized with a broad variety of inflammation-related proteins (complement factors, acute-phase proteins, pro-inflammatory cytokines) and clusters of activated microglia. These findings have led to the view that the amyloid plaque is the nidus of a non-immune mediated chronic inflammatory response locally induced by fibrillar Aβ deposits. Recent neuropathological studies show a close relationship between fibrillar Aβ deposits, inflammation and neuroregeneration in relatively early stages of AD pathology preceding late AD stages characterized by extensive tau-related neurofibrillary changes.In the present work we will review the role of inflammation in the early stage of AD pathology and particularly the role of inflammation in Aβ metabolism and deposition. We also discuss the possibilities of inflammation-based therapeutic strategies in AD.

Familial aggregation in frontotemporal dementia

Objective and background Frontotemporal dementia (FTD) is a common, non-Alzheimers dementia. Its familial occurrence has been reported, but the frequency of positive family history is unknown. Methods We carried out a nationwide genetic-epidemiologic study of FTD in the Dutch population of 15 million people. The family history of dementia was analyzed in 74 FTD patients and 561 age- and gender-matched control subjects. Results We found one or more first-degree relatives with dementia before age 80 in 38% (28 of 74) of FTD patients, but only in 15% (84 of 561) of control subjects. Ten percent of FTD patients had two or more first-degree relatives with dementia compared with 0.9% of the control subjects. Seven percent of FTD patients showed the ApoE4E4 genotype versus 2.3% of the control subjects. The first-degree relatives of FTD had a risk of 22% for dementia before age 80 compared with 11% in relatives of control subjects. The age of onset of dementia in affected first-degree relatives of FTD patients (60.9 ± 10.6 years) was significantly lower than among affected relatives of control subjects (72.3 ± 8.5 years). The first-degree relatives of FTD patients were 3.5 times (95% CI, 2.4 to 5.2) more at risk for developing dementia before age 80 than relatives of control subjects. The hazard ratio in the subgroup with unknown linkage to chromosome 17 was 2.4 (95% CI, 1.5 to 3.7). Conclusion This study documents the importance of genetic factors in a proportion of FTD patients with the age at onset of dementia in first-degree relatives being 11 years earlier than in the general population.

Neuroinflammation - An Early Event in Both the History and Pathogenesis of Alzheimer's Disease

Background: About hundred years ago, Oskar Fischer proposed that the senile plaques are the consequence of the deposition of a foreign substance that could induce an inflammatory response leading to an abnormal neuritic response of the surrounding neurons. Objectives: To show that the interest in inflammation in Alzheimer’s disease (AD) is not only an early event in the history of AD but that inflammation is also an early event in the pathogenesis of AD. Methods: Evaluation of the neuropathological, epidemiological and genetic evidence for a role of inflammation early in the pathogenesis of AD. Results: Neuropathological studies show presence of activated microglia and inflammation-related mediators in the cerebral neocortex of autopsied patients with a low Braak stage for AD pathology. Prospective population-based cohort studies indicate that higher serum levels of acute phase proteins predict dementia. On a genetic level, it was found that the production capacity of proinflammatory cytokines after stimulation with lipopolysaccharide (a process that is under strong genetic control) is higher in offspring with a parental history of late-onset AD. Conclusion: Neuropathological studies show that a neuroinflammatory response in the cerebral neocortex parallels the early stages of AD pathology and precedes the late stage, tau-related pathology. Epidemiological and genetic studies indicate that systemic markers of the innate immunity are risk factors for late-onset AD.

Neuroinflammatory perspectives on the two faces of Alzheimer’s disease

Summary.The amyloid plaques in Alzheimer’s disease (AD) brains are co-localized with a broad variety of inflammation-related proteins (complement factors, acute-phase proteins, pro-inflammatory cytokines) and clusters of activated microglia. The present data suggest that Aβ deposits in AD brains are closely associated with a locally induced, non-immune mediated, chronic inflammatory response. Clinicopathological and neuroradiological studies show that activation of microglia is a relatively early pathogenic event that precedes the process of neuropil destruction in AD. Epidemiological studies indicate that polymorphisms of certain cytokines and acute-phase proteins that are colocalized with Aβ plaques, are genetic risk factors of AD. Epidemiological studies have also shown that the use of classical nonsteroidal anti-inflammatory drugs (NSAIDs) can prevent the risk of AD but clinical trials with anti-inflammatory drugs in AD patients were negative. These findings indicate that anti-inflammatory agents can be helpful in the prevention but not in the treatment of AD. So, pathological, genetic and therapeutic studies suggest that inflammatory mechanisms are most likely involved in the early steps of the pathological cascade. In the autosomal dominant inherited forms of AD the primary factor is the increased production of Aβ1–42 resulting into fibrillar Aβ deposition that elicits a brain inflammatory response. The etiology of the sporadic forms is yet unknown but this subtype is considered to be heterogeneous and multifactorial in its pathogenesis. Here we review the evidence that inflammation related events could be a critical etiological factor in certain forms of the sporadic AD.

Changes in vasopressin cells of the rat suprachiasmatic nucleus with aging

The suprachiasmatic nucleus (SCN) of the hypothalamus is considered to be the endogenous clock of the mammalian brain, regulating circadian rhythmicity of a great number of physiological and behavioural parameters. Numerous studies have shown that the circadian organization in the rat is progressively disturbed in senescence. However, a recent study by Peng et al.17 using conventionally stained material, revealed no decrease in overall SCN cell number of senescent rats. Their results have now been confirmed in this study. In addition, an increase in SCN volume (P = 0.02) and nucleus diameter (P = 0.001) and an overall decrease in cell density (P = 0.006) was observed. All these parameters seem to confirm the absence of a general degeneration in the senescent SCN. However, the major aim of the present study was to determine whether a well-defined population of neurons, i.e. the vasopressinergic (AVP) cells of the SCN, shows changes with aging. Immunocytochemical staining with antivasopressin and morphometry revealed a decrease of 31% (P = 0.007) in the number of these SCN neurons, whereas the remaining vasopressin cells became larger (P = 0.001). There were no statistical significant differences between rats housed in standard cages and those housed in an enriched environment in either age group, but the groups were relative small. Changes in either the number or stainability of SCN vasopressin neurons may be a morphological correlate of changed circadian rhythms in senescence.

Aging and circadian rhythms

Publisher Summary This chapter summarizes the current knowledge about the circadian system and its organization and provides an overview of chronobiological studies in which age or dementia has been treated as independent variable. It also discusses the relevance of considering circadian variations in gerontology and indicates possible fruitful future directions of the research related to aging and circadian rhythms. Circadian rhythms—that is, rhythmic changes with a periodicity of approximately 24 hours—can be observed in organisms ranging from protozoans to humans. Organization in the dimension time is a pervasive characteristic of living systems. The circadian timekeeping system appears to be changed during aging in both animals and humans. Because of the growing interest in gerontology, the number of functional systems for which age-related changes are described is continuously increasing. In contrast to some other systems sensitive to the effects of aging, the circadian timekeeping system is directly implicated in the organization of various important physiological functions. The reduction in suprachiasmatic nuclei (SCN) cell number found in old age and even stronger in Alzheimers disease represents a possible morphological correlate of circadian rhythm alterations in old age.

14-3-3 testing in diagnosing Creutzfeldt–Jakob disease A prospective study in 112 patients

Objective: To study the sensitivity and specificity of 14-3-3 testing in a prospective series of patients suspected of having Creutzfeldt-Jakob disease (CJD). Background: The 14-3-3 protein immunoassay on CSF has favorable test characteristics as a premortem diagnostic tool in CJD. However, the 14-3-3 protein is a normal cellular protein expressed in various tissues, and its presence in CSF reflects extensive destruction of brain tissue as in CJD, but also in ischemic stroke and meningoencephalitis. Methods: 14-3-3 was tested in the CSF of a prospective series of 110 consecutive patients suspected of having CJD. Results: The sensitivity was 97% and the specificity was 87% in this series. False-positive results were mainly caused by stroke and meningoencephalitis. Conclusion: The 14-3-3 protein is a highly sensitive and specific marker for CJD when used in the appropriate clinical context.

Age-related changes in the sleep pattern of male adult rats

In order to study whether or not the age-related changes in the sleep pattern observed in humans also occur in rats, young adult (4 months) and old (22 months) male Wistar rats were implanted with EEG and EMG electrodes for 24 h on-line registration by means of an automatic sleep-classifier. During the 12 h light period, the old rats as compared to the young adult ones showed a significant increase of the time spent awake and a decrease of active sleep time. Furthermore, the light-dark ratio was decreased in the old rats for wakefulness and active sleep. Off-line analysis of the EEG during quiet sleep and active sleep revealed no differences between the two age groups. These results suggest the existence of a number of considerable age-related changes in the sleep pattern of adult rats, which are comparable to those observed in humans.

Chapter 11 - Circadian rhythms and the suprachiasmatic nucleus in perinatal development, aging and Alzheimer's disease

Circadian rhythms are already present in the fetus. At a certain stage of pre-natal hypothalamic development (around 30 weeks of gestation) the fetus becomes responsive to maternal circadian signals. Moreover, recent studies showed that the fetal biological clock is able to generate circadian rhythms, as exemplified by the rhythms of body temperature and heart rate of pre-term babies in the absence of maternal or environmental entrainment factors. Pre-term babies that are deprived of maternal entrainment and kept under constant environmental conditions (e.g., continuous light) in the neonatal intensive care unit run the risk of developing a biological clock dysfunctioning. However, the fact should be acknowledged that at least in mice the development of the circadian pacemaker (i.e., SCN) does not depend on environmental influences (Davis and Menaker, 1981), although other data suggest that severe disruption of the maternal circadian rhythm indeed abolishes the circadian rhythm of the fetal SCN (Shibata and Moore, 1988). During aging and in particular in AD circadian rhythms are disturbed. These disturbances include phase advance and reduced period and amplitude, as well as an increased intradaily variability and a decreased interdaily stability of the rhythm. Among the factors underlying these changes the loss of SCN neurons seems to play a central role. Other contributory factors may be reduced amount of light, degenerative changes in the visual system and the level of activity and decreased melatonin.