Concentrations of monoamines and their metabolites in the cerebrospinal fluid from patients with senile dementia of the Alzheimer type and vascular dementia of the Binswanger type

Cerebrospinal fluid and positron-emission tomography biomarkers for noradrenergic dysfunction in neurodegenerative diseases: a systematic review and meta-analysis

The noradrenergic system shows pathological modifications in aging and neurodegenerative diseases and undergoes substantial neuronal loss in Alzheimer's disease and Parkinson's disease. While a coherent picture of structural decline in post-mortem and in vivo MRI measures seems to emerge, whether this translates into a consistent decline in available noradrenaline levels is unclear. We conducted a meta-analysis of noradrenergic differences in Alzheimer's disease dementia and Parkinson's disease using CSF and PET biomarkers. CSF noradrenaline and 3-methoxy-4-hydroxyphenylglycol levels as well as noradrenaline transporters availability, measured with PET, were summarized from 26 articles using a random-effects model meta-analysis. Compared to controls, individuals with Parkinson's disease showed significantly decreased levels of CSF noradrenaline and 3-methoxy-4-hydroxyphenylglycol, as well as noradrenaline transporters availability in the hypothalamus. In Alzheimer's disease dementia, 3-methoxy-4-hydroxyphenylglycol but not noradrenaline levels were increased compared to controls. Both CSF and PET biomarkers of noradrenergic dysfunction reveal significant alterations in Parkinson's disease and Alzheimer's disease dementia. However, further studies are required to understand how these biomarkers are associated to the clinical symptoms and pathology.

Dysfunction of norepinephrine and its metabolites in Alzheimer's dementia - A review with meta-analysis

Some studies point locus coeruleus cell loss, the central nervous system main source of norepinephrine, to be one of the earliest neuropathological events of Alzheimer's disease (AD). However, there are conflicting reports regarding the level of norepinephrine and its metabolites (3-Methoxy-4-hydroxyphenylglycol (MHPG), 3,5-dihydroxyphenylglycine (DHPG) and 3,4 -dihydroxyphenylglycolaldehyde (DOPEGAL)) in AD patients. Uncover these alterations may be a key factor for understanding cognitive deficits and AD pathology. We review the literature that compare norepinephrine and its metabolites between AD patients and non-demented controls. A meta-analysis did not reveal significant statistical differences, but there was a trend towards a lower level of norepinephrine of AD, with almost no difference in MHPG in the cerebrospinal fluid. Regarding MHPG in plasma, DHPG and DOPEGAL we only performed a qualitative analyse due to the small or absent number of studies. These findings point to a decrease in norepinephrine, what is in line with locus coeluleus cell loss in AD. The absence of statistical difference and an equal level of MHGP could indicate a compensatory mechanism.

YQBS Improves Cognitive Dysfunction in Diabetic Rats: Possible Association with Tyrosine and Tryptophan Metabolism

OBJECTIVE

This study is aimed to determine the metabolomic effects of the hybrid medicine formula Yi-Qi-Bu-Shen (YQBS) on the neurotransmitter aspects of cognitive impairment in diabetic rats.

METHODS

In the current study, streptozotocin (STZ) was used to induce diabetic animal model in male Sprague Dawley (SD) rats. After successful establishment of diabetic SD rats' model, age-matched healthy SD rats and diabetic SD rats were treated with low and high doses of YQBS, and then tested for learning memory ability and analyzed for pathological changes. In addition, neurotransmitter metabolic changes in hippocampal subdivisions of rats from different treated groups were analyzed using liquid chromatography-mass spectrometry (LC-MS) technique.

RESULTS

YQBS could significantly improve memory-cognitive impairment in diabetic rats as evidenced by the shortening of latency to target and the reduction of latency first entrance to target. Moreover, YQBS also improved the pathological alterations in the hippocampal region in the brains of diabetic rats. Metabolomic analysis showed that the expression of noradrenaline hydrochloride was down-regulated and the expressions of levodopa and 5-hydroxytryptophan were up-regulated in the hippocampal tissues of diabetic rats treated with YQBS.

CONCLUSION

These findings demonstrate that YQBS has protective effects against diabetic cognitive dysfunction, which might act through alteration in tyrosine and tryptophan metabolism.

Strong Out-of-Plane Vibrations and Ultrasensitive Detection of Dopamine-like Neurotransmitters

The detection of monoamine neurotransmitters has become a vital research subject due to their high correlations with nervous system diseases, but insufficient detection precisions have obstructed diagnosis of some related diseases. Here, we focus on four monoamine neurotransmitters, dopamine, norepinephrine, epinephrine, and serotonin, to conduct their rapid and ultrasensitive detection. We find that the low-frequency (<200 cm^-1) Raman vibrations of these molecules show some sharp peaks, and their intensities are significantly stronger than those of the high-frequency side. Theoretical calculations identify these peaks to be from strong out-of-plane vibrations of the C-C single bonds at the joint point of the ring-like molecule and its side chain. Using our surface enhanced low-frequency Raman scattering substrates, we show that the detection limit of dopamine as an example can reach 10 nM in artificial cerebrospinal fluid. This work provides a useful way for ultrasensitive and rapid detection of some neurotransmitters.

Association of the MAOB rs1799836 Single Nucleotide Polymorphism and APOE ɛ4 Allele in Alzheimer's Disease

BACKGROUND

The dopaminergic system is functionally compromised in Alzheimer's dis-ease (AD). The activity of monoamine oxidase B (MAOB), the enzyme involved in the degradation of dopamine, is increased during AD. Also, increased expression of MAOB occurs in the post-mortem hippocampus and neocortex of patients with AD. The MAOB rs1799836 polymorphism modulates MAOB transcription, consequently influencing protein translation and MAOB activity. We recently showed that cerebrospinal fluid levels of amyloid β1-42 are decreased in patients carry- ing the A allele in MAOB rs1799836 polymorphism.

OBJECTIVE

The present study compares MAOB rs1799836 polymorphism and APOE, the only con- firmed genetic risk factor for sporadic AD.

METHOD

We included 253 participants, 127 of whom had AD, 57 had mild cognitive impairment, 11 were healthy controls, and 58 suffered from other primary causes of dementia. MAOB and APOE polymorphisms were determined using TaqMan SNP Genotyping Assays.

RESULTS

We observed that the frequency of APOE ɛ4/ɛ4 homozygotes and APOE ɛ4 carriers is sig- nificantly increased among patients carrying the AA MAOB rs1799836 genotype.

CONCLUSION

These results indicate that the MAOB rs1799836 polymorphism is a potential genetic biomarker of AD and a potential target for the treatment of decreased dopaminergic transmission and cognitive deterioration in AD.

New frontiers in Alzheimer's disease diagnostic: Monoamines and their derivatives in biological fluids

Current diagnosis of Alzheimer's disease (AD) relies on a combination of neuropsychological evaluations, biomarker measurements and brain imaging. Nevertheless, these approaches are either expensive, invasive or lack sensitivity to early AD stages. The main challenge of ongoing research is therefore to identify early non-invasive biomarkers to diagnose AD at preclinical stage. Accumulating evidence support the hypothesis that initial degeneration of profound monoaminergic nuclei may trigger a transneuronal spread of AD pathology towards hippocampus and cortex. These studies aroused great interest on monoamines, i.e. noradrenaline (NA), dopamine (D) ad serotonin (5-HT), as early hallmarks of AD pathology. The present work reviews current literature on the potential role of monoamines and related metabolites as biomarkers of AD. First, morphological changes in the monoaminergic systems during AD are briefly described. Second, we focus on concentration changes of these molecules and their derivatives in biological fluids, including cerebrospinal fluid, obtained by lumbar puncture, and blood or urine, sampled via less invasive procedures. Starting from initial observations, we then discuss recent insights on metabolomics-based analysis, highlighting the promising clinical utility of monoamines for the identification of a molecular AD signature, aimed at improving early diagnosis and discrimination from other dementia.

Alterations and interactions of subcortical modulatory systems in Alzheimer's disease

The pathogenesis of Alzheimer's disease (AD) is not fully understood. Here we summarize current knowledge on the involvement of the serotonergic, noradrenergic, dopaminergic, cholinergic, and opioid systems in AD, emphasizing the importance of interactions between the serotonergic and the other subcortical modulatory systems during the progression of AD. In physiological conditions, all neurotransmitter systems function in concert and are interdependent at both the neuroanatomical and molecular levels. Through their early involvement in AD, cognitive and behavioral abilities that rely on their interactions also become disrupted. Considering that serotonin (5HT) regulates the release of noradrenaline (NA), dopamine (DA) and acetylcholine (ACh), any alteration in 5HT levels leads to disturbance of NA, DA, and ACh homeostasis in the brain. One of the earliest pathological changes during the prodromal phase of AD is a decrease of serotonergic transmission throughout the brain, with serotonergic receptors being also affected. Additionally, serotonergic and noradrenergic as well as serotonergic and dopaminergic nuclei are reciprocally interconnected. As the serotonergic dorsal raphe nucleus (DRN) is affected by pathological changes early in AD, and the noradrenergic locus coeruleus (LC) and dopaminergic ventral tegmental area (VTA) exhibit AD-related pathological changes, their connectivity also becomes altered in AD. Such disrupted interactions among neurotransmitter systems in AD can be used in the development of multi-target drugs. Some of the potential AD therapeutics (such as ASS234, RS67333, tropisetron) target multiple neurotransmitter systems to achieve the best possible improvement of cognitive and behavioral deficits observed in AD. Here, we review how serotonergic system interacts with other subcortical modulatory systems (noradrenergic, dopaminergic, cholinergic, and opioid systems) during AD.

The multi-faceted impact of methamphetamine on Alzheimer's disease: From a triggering role to a possible therapeutic use

Although it has been initially synthesized for therapeutic purposes and currently FDA-approved and prescribed for obesity, attention-deficit/hyperactivity disorder, narcolepsy and depression, methamphetamine became a recreational drug that is nowadays massively manufactured illegally. Because it is a powerful and extremely addictive psychotropic agent, its abuse has turned out to become a major health problem worldwide. Importantly, the numerous effects triggered by this drug induce neurotoxicity in the brain ultimately leading to serious neurological impairments, tissue damage and neuropsychological disturbances that are reminiscent to most of the symptoms observed in Alzheimer's disease and other pathological manifestations in aging brain. In this context, there is a growing number of compelling evidence linking methamphetamine abuse with a higher probability of developing premature Alzheimer's disease and consequent neurodegeneration. This review proposes to establish a broad assessment of the effects that this drug can generate at the cellular and molecular levels in connection with the development of the age-related Alzheimer's disease. Altogether, the objective is to warn against the long-term effects that methamphetamine abuse may convey on young consumers and the increased risk of developing this devastating brain disorder at later stages of their lives, but also to discuss a more recently emerging concept suggesting a possible use of methamphetamine for treating this pathology under proper and strictly controlled conditions.

Neuropharmacology of the Neuropsychiatric Symptoms of Dementia and Role of Pain: Essential Oil of Bergamot as a Novel Therapeutic Approach

Aging of the population makes of dementia a challenge for health systems worldwide. The cognitive disturbance is a serious but not the only issue in dementia; behavioral and psychological syndromes known as neuropsychiatric symptoms of dementia remarkably reduce the quality of life. The cluster of symptoms includes anxiety, depression, wandering, delusions, hallucinations, misidentifications, agitation and aggression. The pathophysiology of these symptoms implicates all the neurotransmitter systems, with a pivotal role for the glutamatergic neurotransmission. Imbalanced glutamatergic and GABAergic neurotransmissions, over-activation of the extrasynaptic N-methyl-D-aspartate (NMDA) receptors and alterations of the latter have been linked to the development of neuropsychiatric symptoms experienced by almost the entire demented population. Drugs with efficacy and safety for prevention or long term treatment of these disorders are not available yet. Aromatherapy provides the best evidence for positive outcomes in the control of agitation, the most resistant symptom. Demented patients often cannot verbalize pain, resulting in unrelieved symptoms and contributing to agitation. Bergamot essential oil provides extensive preclinical evidence of analgesic properties. Incidentally, the essential oil of bergamot induces anxyolitic-like effects devoid of sedation, typical of benzodiazepines, with a noteworthy advantage for demented patients. These data, together with the reported safety profile, form the rational basis for bergamot as a neurotherapeutic to be trialed for the control of behavioral and psychological symptoms of dementia.

Rosmarinic acid suppresses Alzheimer's disease development by reducing amyloid β aggregation by increasing monoamine secretion

A new mechanism is revealed by which a polyphenol, rosmarinic acid (RA), suppresses amyloid β (Aβ) accumulation in mice. Here we examined the brains of mice (Alzheimer's disease model) using DNA microarray analysis and revealed that the dopamine (DA)-signaling pathway was enhanced in the group fed RA versus controls. In the cerebral cortex, the levels of monoamines, such as norepinephrine, 3,4-dihydroxyphenylacetic acid, DA, and levodopa, increased after RA feeding. The expression of DA-degrading enzymes, such as monoamine oxidase B (Maob), was significantly downregulated in the substantia nigra and ventral tegmental area, both DA synthesis regions. Following in vitro studies showing that monoamines inhibited Aβ aggregation, this in vivo study, in which RA intake increased concentration of monoamine by reducing Maob gene expression, builds on that knowledge by demonstrating that monoamines suppress Aβ aggregation. In conclusion, RA-initiated monoamine increase in the brain may beneficially act against AD.

Complex noradrenergic dysfunction in Alzheimer's disease: Low norepinephrine input is not always to blame

The locus coeruleus-noradrenergic (LC-NA) system supplies the cerebral cortex with norepinephrine, a key modulator of cognition. Neurodegeneration of the LC is an early hallmark of Alzheimer's disease (AD). In this article, we analyze current literature to understand whether NA degeneration in AD simply leads to a loss of norepinephrine input to the cortex. With reported adaptive changes in the LC-NA system at the anatomical, cellular, and molecular levels in AD, existing evidence support a seemingly sustained level of extracellular NE in the cortex, at least at early stages of the long course of AD. We postulate that loss of the integrity of the NA system, rather than mere loss of NE input, is a key contributor to AD pathogenesis. A thorough understanding of NA dysfunction in AD has a large impact on both our comprehension and treatment of this devastating disease.

Noradrenergic Hypothesis Linking Neurodegeneration-Based Cognitive Decline and Astroglia

In the past, manipulation of the cholinergic system was seen as the most likely therapeutic for neurodegeneration-based cognitive decline in Alzheimer's disease (AD) (Whitehouse et al., 1982). However, targeting the noradrenergic system also seems a promising strategy, since more recent studies revealed that in post-mortem tissue from patients with AD and other neurodegenerative disorders there is a robust correlation between cognitive decline and loss of neurons from the Locus coeruleus (LC), a system with diffuse noradrenaline (NA) innervation in the central nervous system (CNS). Therefore, the hypothesis has been considered that increasing NA signaling in the CNS will prevent, or at least halt the progression of neurodegeneration and cognitive decline. A hallmark of the age- and neurodegeneration-related cognitive decline is reduced neurogenesis. We here discuss noradrenergic dysfunction in AD-related cognitive decline in humans and its potential involvement in AD pathology and disease progression. We also focus on animal models to allow the validation of the noradrenergic hypothesis of AD, including those based upon the immunotoxin-mediated ablation of LC based on saporin, a protein synthesis interfering agent, which offers selective and graded demise of LC neurons, Finally, we address how astrocytes, an abundant and functionally heterogeneous cell type of neuroglia maintaining homeostasis, may participate in the regulation of neurogenesis, a new strategy for preventing LC neuron loss.

Monoaminergic neuropathology in Alzheimer's disease

None of the proposed mechanisms of Alzheimer's disease (AD) fully explains the distribution patterns of the neuropathological changes at the cellular and regional levels, and their clinical correlates. One aspect of this problem lies in the complex genetic, epigenetic, and environmental landscape of AD: early-onset AD is often familial with autosomal dominant inheritance, while the vast majority of AD cases are late-onset, with the ε4 variant of the gene encoding apolipoprotein E (APOE) known to confer a 5-20 fold increased risk with partial penetrance. Mechanisms by which genetic variants and environmental factors influence the development of AD pathological changes, especially neurofibrillary degeneration, are not yet known. Here we review current knowledge of the involvement of the monoaminergic systems in AD. The changes in the serotonergic, noradrenergic, dopaminergic, histaminergic, and melatonergic systems in AD are briefly described. We also summarize the possibilities for monoamine-based treatment in AD. Besides neuropathologic AD criteria that include the noradrenergic locus coeruleus (LC), special emphasis is given to the serotonergic dorsal raphe nucleus (DRN). Both of these brainstem nuclei are among the first to be affected by tau protein abnormalities in the course of sporadic AD, causing behavioral and cognitive symptoms of variable severity. The possibility that most of the tangle-bearing neurons of the LC and DRN may release amyloid β as well as soluble monomeric or oligomeric tau protein trans-synaptically by their diffuse projections to the cerebral cortex emphasizes their selective vulnerability and warrants further investigations of the monoaminergic systems in AD.

Epigenetic dysregulation of brainstem nuclei in the pathogenesis of Alzheimer's disease: looking in the correct place at the right time?

Even though the etiology of Alzheimer's disease (AD) remains unknown, it is suggested that an interplay among genetic, epigenetic and environmental factors is involved. An increasing body of evidence pinpoints that dysregulation in the epigenetic machinery plays a role in AD. Recent developments in genomic technologies have allowed for high throughput interrogation of the epigenome, and epigenome-wide association studies have already identified unique epigenetic signatures for AD in the cortex. Considerable evidence suggests that early dysregulation in the brainstem, more specifically in the raphe nuclei and the locus coeruleus, accounts for the most incipient, non-cognitive symptomatology, indicating a potential causal relationship with the pathogenesis of AD. Here we review the advancements in epigenomic technologies and their application to the AD research field, particularly with relevance to the brainstem. In this respect, we propose the assessment of epigenetic signatures in the brainstem as the cornerstone of interrogating causality in AD. Understanding how epigenetic dysregulation in the brainstem contributes to AD susceptibility could be of pivotal importance for understanding the etiology of the disease and for the development of novel diagnostic and therapeutic strategies.

Monoaminergic and Histaminergic Strategies and Treatments in Brain Diseases

The monoaminergic systems are the target of several drugs for the treatment of mood, motor and cognitive disorders as well as neurological conditions. In most cases, advances have occurred through serendipity, except for Parkinson's disease where the pathophysiology led almost immediately to the introduction of dopamine restoring agents. Extensive neuropharmacological studies first showed that the primary target of antipsychotics, antidepressants, and anxiolytic drugs were specific components of the monoaminergic systems. Later, some dramatic side effects associated with older medicines were shown to disappear with new chemical compounds targeting the origin of the therapeutic benefit more specifically. The increased knowledge regarding the function and interaction of the monoaminergic systems in the brain resulting from in vivo neurochemical and neurophysiological studies indicated new monoaminergic targets that could achieve the efficacy of the older medicines with fewer side-effects. Yet, this accumulated knowledge regarding monoamines did not produce valuable strategies for diseases where no monoaminergic drug has been shown to be effective. Here, we emphasize the new therapeutic and monoaminergic-based strategies for the treatment of psychiatric diseases. We will consider three main groups of diseases, based on the evidence of monoamines involvement (schizophrenia, depression, obesity), the identification of monoamines in the diseases processes (Parkinson's disease, addiction) and the prospect of the involvement of monoaminergic mechanisms (epilepsy, Alzheimer's disease, stroke). In most cases, the clinically available monoaminergic drugs induce widespread modifications of amine tone or excitability through neurobiological networks and exemplify the overlap between therapeutic approaches to psychiatric and neurological conditions. More recent developments that have resulted in improved drug specificity and responses will be discussed in this review.

Neuroprotective Effects of Simvastatin and Cilostazol in L-Methionine-Induced Vascular Dementia in Rats

Vascular dementia (VaD) is a degenerative cerebrovascular disorder that leads to progressive decline in cognitive abilities and memory. Several reports demonstrated that oxidative stress and endothelial dysfunction are principal pathogenic factors in VaD. The present study was constructed to determine the possible neuroprotective effects of simvastatin in comparison with cilostazol in VaD induced by L-methionine in rats. Male Wistar rats were divided into four groups. Group I (control group), group II received L-methionine (1.7 g/kg, p.o.) for 32 days. The remaining two groups received simvastatin (50 mg/kg, p.o.) and cilostazol (100 mg/kg, p.o.), respectively, for 32 days after induction of VaD by L-methionine. Subsequently, rats were tested for cognitive performance using Morris water maze test then sacrificed for biochemical and histopathological assays. L-methionine induced VaD reflected by alterations in rats' behavior as well as the estimated neurotransmitters, acetylcholinesterase activity as well as increased brain oxidative stress and inflammation parallel to histopathological changes in brain tissue. Treatment of rats with simvastatin ameliorated L-methionine-induced behavioral, neurochemical, and histological changes in a manner comparable to cilostazol. Simvastatin may be regarded as a potential therapeutic strategy for the treatment of VaD. To the best of our knowledge, this is the first study to reveal the neuroprotective effects of simvastatin or cilostazol in L-methionine-induced VaD. Graphical Abstract ᅟ.

The Locus Coeruleus: Essential for Maintaining Cognitive Function and the Aging Brain

Research on cognitive aging has focused on how decline in various cortical and hippocampal regions influence cognition. However, brainstem regions play essential modulatory roles, and new evidence suggests that, among these, the integrity of the locus coeruleus (LC)-norepinephrine (NE) system plays a key role in determining late-life cognitive abilities. The LC is especially vulnerable to toxins and infection and is often the first place Alzheimer's-related pathology appears, with most people showing at least some tau pathology by their mid-20s. On the other hand, NE released from the LC during arousing, mentally challenging, or novel situations helps to protect neurons from damage, which may help to explain how education and engaging careers prevent cognitive decline in later years.

Blink Reflex May Help Discriminate Alzheimer Disease From Vascular Dementia

PURPOSE

Dementia has several different etiologies, and vascular dementia (VaD) is considered the second leading cause of dementia after Alzheimer disease (AD). Various studies used blink reflex in different spectrum of neurological diseases as a complementary diagnostic test. We performed blink test in AD, VaD, and mixed dementia to investigate different usefulness of blink reflex in differentiating these types of dementia.

METHODS

Blink reflex was performed for patients with AD (n = 18), VaD (n = 17), mixed dementia (n = 19), and normal subjects (n = 20). The absolute latency of R1, R2, and contralateral R2 (R2c) was determined and then compared with normal values. We used ROC curve to determine the screening cut-off value for R2 and R2c to discriminate dementia with vascular component and AD.

RESULTS

The mean age ± SD of patients was 71.61 ± 8.23, 66.71 ± 11.48, 75.26 ± 8.32, and 66.60 ± 3.91 years in 4 groups of AD, VaD, mixed dementia, and normal, respectively. R2 and R2c were recorded in fewer number of subjects with VaD or mixed dementia than AD and normal subjects. For mean R2 latency higher than 45 milliseconds, the sensitivity and specificity were 42% and 100%, respectively, and for latency higher than 45 milliseconds, the sensitivity and specificity were 72% and 89%, respectively.

CONCLUSIONS

R2 and R2c components of blink reflex could specifically discriminate between Alzheimer and dementia with vascular component. The interruption of descending corticoreticular pathways by small infarcts could explain it.

Noradrenergic dysfunction in Alzheimer's disease

The brain noradrenergic system supplies the neurotransmitter norepinephrine throughout the brain via widespread efferent projections, and plays a pivotal role in modulating cognitive activities in the cortex. Profound noradrenergic degeneration in Alzheimer's disease (AD) patients has been observed for decades, with recent research suggesting that the locus coeruleus (where noradrenergic neurons are mainly located) is a predominant site where AD-related pathology begins. Mounting evidence indicates that the loss of noradrenergic innervation greatly exacerbates AD pathogenesis and progression, although the precise roles of noradrenergic components in AD pathogenesis remain unclear. The aim of this review is to summarize current findings on noradrenergic dysfunction in AD, as well as to point out deficiencies in our knowledge where more research is needed.

Elevation of rat brain tyrosine levels by phenelzine is mediated by its active metabolite β-phenylethylidenehydrazine

Phenelzine, a non-selective irreversible inhibitor of monoamine oxidase (MAO), has been used in the treatment of depression and anxiety disorders for several decades. It is a unique inhibitor of MAO as it is also a substrate for MAO, with one of the metabolites being β-phenylethylidenehydrazine (PEH), and it also inhibits several transaminases (e.g. GABA transaminase) in the brain when administered i.p. to rats. Administration of either phenelzine or PEH to rats has been reported to produce dramatic increases in rat brain levels of GABA and alanine while reducing levels of glutamine; these effects are abolished for phenelzine, but not for PEH, when the animals are pre-treated with another MAO inhibitor, suggesting that they are mediated by the MAO-catalyzed formation of PEH from phenelzine. In the present report, we have found that phenelzine and E- and Z-geometric isomers of PEH significantly increased rat whole brain concentrations of L-tyrosine. In a time-response study, acute administration of phenelzine, E-PEH and Z-PEH (30 mg/kg i.p.) elevated rat whole brain L-tyrosine levels at 3 and 6h following injection, reaching approximately 265-305% of vehicle-treated controls at 3h. To determine whether the effect on L-tyrosine is MAO-dependent, animals were pre-treated with the non-selective MAO inhibitor tranylcypromine (1mg/kg i.p.) prior to administration of phenelzine, racemic PEH or vehicle controls. This pre-treatment reversed the effects of phenelzine, but not of PEH, on brain L-tyrosine levels, suggesting that the tyrosine-elevating property of phenelzine is largely the result of its active metabolite PEH. These results are discussed in relation to possible therapeutic applications of these drugs.

Ascending monoaminergic systems alterations in Alzheimer's disease. translating basic science into clinical care

Extensive neuropathological studies have established a compelling link between abnormalities in structure and function of subcortical monoaminergic (MA-ergic) systems and the pathophysiology of Alzheimer's disease (AD). The main cell populations of these systems including the locus coeruleus, the raphe nuclei, and the tuberomamillary nucleus undergo significant degeneration in AD, thereby depriving the hippocampal and cortical neurons from their critical modulatory influence. These studies have been complemented by genome wide association studies linking polymorphisms in key genes involved in the MA-ergic systems and particular behavioral abnormalities in AD. Importantly, several recent studies have shown that improvement of the MA-ergic systems can both restore cognitive function and reduce AD-related pathology in animal models of neurodegeneration. This review aims to explore the link between abnormalities in the MA-ergic systems and AD symptomatology as well as the therapeutic strategies targeting these systems. Furthermore, we will examine possible mechanisms behind basic vulnerability of MA-ergic neurons in AD.

Development of amyloid burden in African Green monkeys

The vervet is an old world monkey increasingly being used as a model for human diseases. In addition to plaques and tangles, an additional hallmark of Alzheimer's disease is damage to neurons that synthesize noradrenaline (NA). We characterized amyloid burden in the posterior temporal lobe of young and aged vervets, and compared that with changes in NA levels and astrocyte activation. Total amyloid beta (Aβ)40 and Aβ42 levels were increased in the aged group, as were numbers of amyloid plaques detected using antibody 6E10. Low levels of Aβ42 were detected in 1 of 5 younger animals, although diffusely stained plaques were observed in 4 of these. Increased glial fibrillary acidic protein staining and messenger RNA levels were significantly correlated with increased age, as were cortical NA levels. Levels of Aβ42 and Aβ40, and the number of 6E10-positive plaques, were correlated with NA levels. Interestingly messenger RNA levels of glial derived neurotrophic factor, important for noradrenergic neuronal survival, were reduced with age. These findings suggest that amyloid pathology in aged vervets is associated with astrocyte activation and higher NA levels.

Baseline saliva level of 3-methoxy-4-hydroxyphenylglycole (MHPG) associates with a consequent cognitive decline in non-demented elderly subjects: three-years follow-up study

The aim of the study was to explore the relation between saliva level of 3-methoxy-4-hydroxy-phenylglycol (MHPG) and a later cognitive decline in non-demented elderly subjects. We have reported that sMHPG in 214 elderly subjects living in the community (age 74.5±5.9years) was associated with scores on the Mini-Mental State Examination (MMSE) and the Frontal Assessment Battery (FAB) in 2004 to 2006 (Time A). The same cohort underwent these cognitive tests again from 2007 to 2009 (Time B). The cognitive function of the 147 of 214 subjects could be reassessed by the same cognitive tests. The score on the FAB, but not the MMSE, was significantly reduced at Time B (14.6±2.6) compared with that of Time A (15.2±1.9). There was a significant negative correlation between the baseline sMHPG and the changes in the FAB score subtracted from Time B to Time A or the scores on the FAB at Time B in men, but not at Time A. These correlations were not found in women. These data indicate that high sMHPG might be associated with subsequent cognitive decline assessed by the FAB in non-demented elderly men living in the community.

Metabolite profiling of Alzheimer's disease cerebrospinal fluid

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive loss of cognitive functions. Today the diagnosis of AD relies on clinical evaluations and is only late in the disease. Biomarkers for early detection of the underlying neuropathological changes are still lacking and the biochemical pathways leading to the disease are still not completely understood. The aim of this study was to identify the metabolic changes resulting from the disease phenotype by a thorough and systematic metabolite profiling approach. For this purpose CSF samples from 79 AD patients and 51 healthy controls were analyzed by gas and liquid chromatography-tandem mass spectrometry (GC-MS and LC-MS/MS) in conjunction with univariate and multivariate statistical analyses. In total 343 different analytes have been identified. Significant changes in the metabolite profile of AD patients compared to healthy controls have been identified. Increased cortisol levels seemed to be related to the progression of AD and have been detected in more severe forms of AD. Increased cysteine associated with decreased uridine was the best paired combination to identify light AD (MMSE>22) with specificity and sensitivity above 75%. In this group of patients, sensitivity and specificity above 80% were obtained for several combinations of three to five metabolites, including cortisol and various amino acids, in addition to cysteine and uridine.

Differential response of the central noradrenergic nervous system to the loss of locus coeruleus neurons in Parkinson's disease and Alzheimer's disease

In Parkinson's disease (PD), there is a significant loss of noradrenergic neurons in the locus coeruleus (LC) in addition to the loss of dopaminergic neurons in the substantia nigra (SN). The goal of this study was to determine if the surviving LC noradrenergic neurons in PD demonstrate compensatory changes in response to the neuronal loss, as observed in Alzheimer's disease (AD). Tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DBH) mRNA expression in postmortem LC tissue of control and age-matched PD subjects demonstrated a significant reduction in the number of noradrenergic neurons in the LC of PD subjects. TH mRNA expression/neuron did not differ between control and PD subjects, but DBH mRNA expression/neuron was significantly elevated in PD subjects compared to control. This increase in DBH mRNA expression in PD subjects is not a response to neuronal loss because the amount of DBH mRNA expression/neuron in AD subjects was not significantly different from control. Norepinephrine transporter (NET) binding site concentration in the LC of PD subjects was significantly reduced over the cell body region as well as the peri-LC dendritic zone. In PD subjects, the loss of dendrites from surviving noradrenergic neurons was also apparent with TH-immunoreactivity (IR). This loss of LC dendritic innervation in PD subjects as measured by TH-IR was not due to LC neuronal loss because TH-IR in AD subjects was robust, despite a similar loss of LC neurons. These data suggest that there is a differential response of the noradrenergic nervous system in PD compared to AD in response to the loss of LC neurons.

Increases in serotonergic neuronal activity following intracerebroventricular administration of AF64A in rats

Changes in the serotonergic nervous system after the intracerebroventricular (i.c.v.) administration of ethylcholine aziridinium (AF64A, 3 nmol/each ventricle) were studied in rats. Two weeks after the infusion of AF64A, the levels of 5-HT and 5-HIAA in microdialysed cerebrospinal fluid (CSF), the levels of total 5-HT and 5-HIAA, the density of serotonin uptake sites and the activities of tryptophan hydroxylase (TPH) and monoamine oxidase (MAO) in various brain regions were determined. After AF64A administration, the concentrations of 5-HT in lateral ventricle were increased and the levels of 5-HIAA were decreased. However, the hippocampal levels of total 5-HT were decreased without changes in the levels of 5-HIAA and the hippocampal turnover rates of 5-HT increased. Also, the density of uptake sites of serotonin ([(3)H]citalopram binding sites) was decreased in the various brain. The activities of TPH were increased in striatum and frontal cortex and the activity of MAO was also increased in striatum. These results indicate that AF64A induces an increase in serotonergic neuronal activity and decreased densities of 5-HT uptake sites which may affect the change in the other parameters of serotonergic neuronal activities. Furthermore, these results suggest that the impaired cholinergic neuronal activity induces the alteration in the serotonergic nervous activities.

Relationship between saliva level of 3-methoxy-4-hydroxyphenylglycol and mental health in the elderly general population

AIMS

A large number of studies on the monoamine systems in Alzheimer's disease (AD) have found abnormalities of the noradrenergic system in the brain, but there has been no report concerning the relationship between noradrenergic activity and cognitive function in elderly living in a community. The aim of the present study was to explore the relationship between saliva level of 3-methoxy-4-hydroxyphenylglycol (sMHPG) and mental health in this population.

METHODS

The study was to examine the relationship between sMHPG and performance on the Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB), and Beck Depression Inventory (BDI) in 213 elderly people living in the local community.

RESULTS

sMHPG in female subjects was positively correlated with age (r = 0.24, P = 0.003) and negatively correlated with scores on the MMSE (r = -0.26, P = 0.0016) and FAB (r = -0.19, P = 0.024), even after controlling for the effect of age (MMSE r = -0.20, P = 0.013). Notably, sMHPG was correlated with the pentagon drawing score (P = 0.0008) of MMSE. sMHPG was significantly correlated with BDI score in male subjects, but negatively correlated in female subjects. A gender difference was found in the relationship between the sMHPG and BDI score.

CONCLUSION

The measurement of sMHPG may be a useful marker of mental health in elderly community-dwelling subjects.

Changes in adrenoreceptors in the prefrontal cortex of subjects with dementia: evidence of compensatory changes

In Alzheimer's disease (AD) there is a significant loss of locus coeruleus (LC) noradrenergic neurons. However, recent work has shown the surviving noradrenergic neurons to display many compensatory changes, including axonal sprouting to the hippocampus. The prefrontal cortex (PFC) is a forebrain region that is affected in dementia, and receives innervation from the LC noradrenergic neurons. Reduced PFC function can reduce cognition and disrupt behavior. Because the PFC is an important area in AD, we determined if noradrenergic innervation from the LC noradrenergic neurons is maintained and if adrenoreceptors are altered postsynaptically. Presynaptic PFC alpha2-adrenoreceptor (AR) binding site density, as determined by 3H-RX821002, suggests that axons from surviving noradrenergic neurons in the LC are sprouting to the PFC of subjects with dementia. Changes in postsynaptic alpha1-AR in the PFC of subjects with dementia indicate normal to elevated levels of binding sites. Expression of alpha1-AR subtypes (alpha1A- and alpha1D-AR) and alpha2C-AR subtype mRNA in the PFC of subjects with dementia is similar to what was observed in the hippocampus with one exception, the expression of alpha1A-AR mRNA. The expression of the alpha1A-AR mRNA subtype is significantly reduced in specific layers of the PFC in subjects with dementia. The loss of alpha1A-, alpha1D- and alpha2C-AR mRNA subtype expression in the PFC may be attributed to neuronal loss observed in dementia. These changes in postsynaptic AR would suggest a reduced function of the PFC. Consequence of this reduced function of the PFC in dementia is still unknown but it may affect memory and behavior.

Locus coeruleus neurofibrillary degeneration in aging, mild cognitive impairment and early Alzheimer's disease

Neurofibrillary degeneration in the nucleus basalis and a loss of its cortical cholinergic projections are prominent components of the neuropathology in Alzheimer's disease (AD). The AD brain is also associated with a degeneration of the noradrenergic projections arising from the nucleus locus coeruleus (LC), but the time course of this lesion is poorly understood. To determine whether the LC displays neurofibrillary abnormalities early in the course of events leading to AD, we examined tissue specimens from seven cognitively normal controls and five subjects at the stages of mild cognitively impairment (MCI) or early AD. Tyrosine hydroxylase immunochemistry was used as a marker of LC neurons while AT8 immunolabeling visualized abnormal tau associated with neurofibrillary tangles and their precursors. Thioflavine-S was used as a marker for fully developed tangles. We found that AT8-positive labeling and thioflavine-S positive tangles were present in both groups of specimens. However, the percentage of neurons containing each of these markers was significantly higher in the cognitively impaired group. The MMSE scores displayed a negative correlation with both markers of cytopathology. These results indicate that cytopathology in the LC is an early event in the age-MCI-AD continuum and that it may be listed among the numerous factors that mediate the emergence of the cognitive changes leading to dementia.

Compensatory changes in the noradrenergic nervous system in the locus ceruleus and hippocampus of postmortem subjects with Alzheimer's disease and dementia with Lewy bodies

In Alzheimer's disease (AD), there is a significant loss of locus ceruleus (LC) noradrenergic neurons. However, functional and anatomical evidence indicates that the remaining noradrenergic neurons may be compensating for the loss. Because the noradrenergic system plays an important role in learning and memory, it is important to determine whether compensation occurs in noradrenergic neurons in the LC and hippocampus of subjects with AD or a related dementing disorder, dementia with Lewy bodies (DLB). We observed profound neuronal loss in the LC in AD and DLB subjects with three major changes in the noradrenergic system consistent with compensation: (1) an increase in tyrosine hydroxylase (TH) mRNA expression in the remaining neurons; (2) sprouting of dendrites into peri-LC dendritic zone, as determined by alpha2-adrenoreceptors (ARs) and norepinephrine transporter binding sites; and (3) sprouting of axonal projections to the hippocampus as determined by alpha2-ARs. In AD and DLB subjects, the postsynaptic alpha1-ARs were normal to elevated. Expression of alpha1A- and alpha2A-AR mRNA in the hippocampus of AD and DLB subjects were not altered, but expression of alpha1D- and alpha2C-AR mRNA was significantly reduced in the hippocampus of AD and DLB subjects. Therefore, in AD and DLB subjects, there is compensation occurring in the remaining noradrenergic neurons, but there does appear to be a loss of specific AR in the hippocampus. Because changes in these noradrenergic markers in AD versus DLB subjects were similar (except neuronal loss and the increase in TH mRNA were somewhat greater in DLB subjects), the presence of Lewy bodies in addition to plaques and tangles in DLB subjects does not appear to further affect the noradrenergic compensatory changes.

Propranolol for disruptive behaviors in nursing home residents with probable or possible Alzheimer disease: a placebo-controlled study

OBJECTIVE

Enhanced behavioral responsiveness to central nervous system (CNS) norepinephrine (NE) in Alzheimer disease (AD) may contribute to the pathophysiology of disruptive behaviors such as aggression, uncooperativeness with necessary care, irritability, and pressured pacing. We evaluated the efficacy of the beta-adrenergic antagonist propranolol for treatment-resistant disruptive behaviors and overall behavioral status in nursing home residents with probable or possible AD.

METHODS

Thirty-one subjects (age 85 +/- 8 [SD]) with probable or possible AD and persistent disruptive behaviors that interfered with necessary care were randomized to propranolol (n = 17) or placebo (n = 14) in a double-blind study. Stable doses of previously prescribed psychotropics were maintained at pre-study dose during the study. Following a propranolol or placebo dose titration period of up to 9 days (per a dosing algorithm), subjects were maintained on maximum achieved dose for 6 weeks. Primary outcome measures were the Neuropsychiatric Inventory (NPI) and the Clinical Global Impression of Change (CGIC).

RESULTS

Propranolol augmentation (mean achieved dose 106 +/- 38 mg/d) was significantly more effective than placebo for improving overall behavioral status on the total NPI score and CGIC. Improvement in individual NPI items within propranolol subjects was significant only for "agitation/aggression" and "anxiety," and reached borderline statistical significance favoring propranolol over placebo only for "agitation/aggression." Pressured pacing and irritability did not appear responsive to propranolol. In propranolol subjects rated "moderately improved" or "markedly improved" on the CGIC at the end of the double-blind study phase, improvement of overall behavioral status had diminished substantially after 6 months of open-label propranolol treatment.

CONCLUSION

Short-term propranolol augmentation treatment appeared modestly effective and well tolerated for overall behavioral status in nursing home residents with probable or possible AD complicated by disruptive behaviors. Propranolol may be helpful specifically for aggression and uncooperativeness (the behaviors assessed by the NPI "agitation/aggressiveness" item). However, the usefulness of propranolol in this very old and frail population was limited by the high frequency of relative contraindications to beta-adrenergic antagonist treatment and diminution of initial behavioral improvements over time.

Normal dopaminergic and serotonergic metabolites in cerebrospinal fluid and blood of restless legs syndrome patients

Cerebrospinal fluid (CSF) and blood obtained from 22 untreated or scarcely treated patients with moderate to severe restless legs syndrome (RLS; mean age, 58.6 +/- 13 years) and 11 control subjects (mean age, 56.6 +/- 12.9 years) were investigated for biogenic amines between 6:00 and 8:00 PM. We did not find any significant differences in the CSF concentrations of homovanillic acid, 3-ortho- methyl-dopa, levodopa, 5-hydroxytryptophan, 5-hydroxyindoleacetic acid, tetrahydrobiopterin, dihydrobiopterin, 5-methyltetrahydrofolate, and neopterin. In addition, serotonin in whole blood and plasma activity of aromatic amino acid decarboxylase were all normal. Our results suggest that dopaminergic and serotonergic release is not substantially affected in RLS.

Difficulties in establishing reference intervals for special fluids: the example of 5-hydroxyindoleacetic acid and homovanillic acid in cerebrospinal fluids

Biochemical measurements in “special fluids” are complicated with the problem of reference intervals. Reference intervals are difficult to establish for these types of samples since they are usually only collected in patients with clinical suspicion of disease. Determination of neurotransmitter metabolites in cerebrospinal fluid illustrates this difficulty. This paper will review the factors and circumstances that have been identified or are suspected to modifythe concentration of 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) in cerebrospinal fluid. In addition to obvious parameters such as age-related variation that can affect the concentration of 5-HIAA and HVA in cerebrospinal fluid, a varietyof other factors can explain the wide range of “control” group sizes reported in the literature. Reference intervals must take into account the purpose of cerebrospinal fluid examinations, whether they be prospective studies to explore physio-pathologic relationships or for diagnostic purposes. In the latter case, certain neurological disorders cannot be excluded if a single measured value is within the reference interval.

Tyrosine hydroxylase and norepinephrine transporter mRNA expression in the locus coeruleus in Alzheimer's disease

Despite the loss of locus coeruleus (LC) noradrenergic neurons in Alzheimer's disease (AD), cerebrospinal fluid norepinephrine (NE) levels are normal or increased in AD. This paradox suggests compensatory upregulation of NE synthetic capacity or downregulation of the NE transporter (NET) in the remaining LC neurons. LC tyrosine hydroxylase (TH) mRNA expression in the LC was measured in AD subjects (n=5) and in age and gender comparable non-demented subjects (n=6). When AD subjects were divided into those still ambulatory prior to death (CDR 3/4) and those in a prolonged 'vegetative' state prior to death (CDR 5), differences among groups became apparent at specific levels of the LC. In CDR 3/4 AD subjects there was increased TH mRNA expression per neuron compared to non-demented subjects in the caudal half of the LC. However, expression of NET mRNA in the same subjects was not significantly different at any level of the LC. These preliminary results suggest an upregulation of NE biosynthetic capacity in at least some LC neurons in AD prior to the very late stage of the disease.

The role of norepinephrine in the pathophysiology of cognitive disorders: potential applications to the treatment of cognitive dysfunction in schizophrenia and Alzheimer's disease

The role of noradrenergic neurotransmission in normal cognitive functions has been extensively investigated, however, the involvement of noradrenergic functions in the cognitive impairment associated with schizophrenia and Alzheimer's disease has not been as intensively considered. The limited ability of atypical antipsychotics to treat the cognitive impairment of schizophrenia, and cholinomimetics to treat the cognitive impairment of Alzheimer's disease, may be related to the influence of a multiplicity of neurotransmitter abnormalities including noradrenergic dysfunction, which these treatments do not address. The evidence of noradrenergic dysfunction occurring concomitantly with dopamine dysfunction in schizophrenia and acetylcholine dysfunction in Alzheimer's disease supports therapeutic approaches using noradrenergic drugs in combination with neuroleptics and cholinesterase inhibitors, respectively, to enhance the treatment of cognitive impairment. Given the results of animal and human studies, it appears that alpha-2A agonists may be the optimal choice for this purpose.

Patterns of cerebrospinal fluid catechols support increased central noradrenergic responsiveness in aging and Alzheimer's disease

BACKGROUND

High cerebrospinal fluid (CSF) norepinephrine (NE) concentrations in aging and Alzheimer's disease (AD) could reflect decreased NE clearance from central nervous system (CNS) extracellular fluid or increased release of NE into CNS extracellular fluid. Measuring CSF concentrations of the intraneuronal NE metabolite dihydroxyphenylglycol (DHPG), an estimate of NE clearance, and the NE precursor dihydroxyphenylacetic acid (DOPA), an estimate of NE biosynthesis, can help differentiate these mechanisms.

METHODS

NE, DHPG, and DOPA were determined by HPLC in CSF and plasma obtained following yohimbine, clonidine, and placebo. Ten AD, 10 older, and 11 young subjects were studied.

RESULTS

CSF DOPA following yohimbine was higher in older and AD than in young subjects. CSF DHPG did not differ among groups. Plasma DOPA following yohimbine was higher in AD than in young subjects.

CONCLUSIONS

During alpha-2 adrenoreceptor blockade in both aging and AD, there are increased responses of CNS NE biosynthesis and release with unchanged CNS NE clearance. This pattern is consistent with partial loss of CNS noradrenergic neurons with compensatory activation of remaining CNS noradrenergic neurons. Given the marked loss of locus coeruleus (LC) noradrenergic neurons in AD, achievement of high CSF NE suggests particularly prominent compensatory activation of remaining LC neurons in this disorder.

Decreased monoamine metabolites in frontotemporal dementia and Alzheimer's disease

The concentrations of the monoamine metabolites homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycol (HMPG) in the cerebrospinal fluid (CSF) of patients with clinical frontotemporal dementia (FTD; n = 30), early onset Alzheimer's disease (EAD; n = 33), late onset Alzheimer's disease (LAD, n = 27) and normal controls (n = 31) were determined using HPLC. ANCOVA showed no significant effect of neuroleptic medication, extrapyramidal signs, myoclonia or gender on the CSF levels of the monoamine metabolites. Homovanillic acid was significantly reduced in all diagnostic groups (FTD, p = 0.0002; EAD, p = 0.016; LAD, p = 0.013). 5-Hydroxyindoleacetic acid was significantly reduced in EAD (p = 0.013) and in LAD (p = 0.0014), and HMPG was reduced in LAD only (p = 0.020). HMPG was significantly higher in FTD compared to EAD (p = 0.0005) and LAD (p = 0.0003). CSF-5-HIAA was significantly reduced in patients with antidepressant medication (p = 0.006). ANCOVA within the FTD group showed no significant effect of neuroleptic or antidepressant medication, extrapyramidal signs, myoclonia, gender or FTD subtype on the CSF levels of the monoamine metabolites. The results suggest that CSF-HMPG might differentiate FTD from EAD and LAD, but not from normals.

Concentration of catecholamines and indoleamines in the cerebrospinal fluid of patients with vascular parkinsonism compared to Parkinson's disease patients

The concentration of catecholamines and indoleamines in the cerebrospinal fluid of patients with vascular parkinsonism (VP) was compared to that in patients with Parkinson's disease (PD) and controls. Compared to the controls, the concentration of tyrosine was significantly higher, and the concentration of L-dopa and 3-O-methyldopa (3-OMD) was significantly lower in both VP and PD patients. The balance between the 3-OMD/L-dopa and dopamine (DA)/L-dopa ratios was changed in favor of 3-OMD/L-dopa in both VP patients and PD patients suggesting the preservation of a compensatory mechanism. All these changes were less marked in VP patients than in PD patients. A remarkable finding was that in contrast to PD patients the concentration of DA and norepinephrine (NE) was significantly higher in VP patients than in the controls. The decrease in the concentration of 5-hydroxytryptamine (5-HT) was significantly greater in VP patients than in PD patients. In PD patients, the concentration of DA, NE, and 5-HT showed significant correlation with the severity of motor symptoms. In VP patients, the concentration of 5-HT alone showed significant correlation with the severity of motor symptoms and cognitive dysfunction. These findings suggest that VP patients may have similar disturbances in the DA synthesis pathway as PD patients, but differ from PD patients in that the concentrations of DA and NE are elevated and the decrease in the 5-HT concentration is greater in VP patients.

Cerebrospinal fluid acetylcholine and choline in vascular dementia of Binswanger and multiple small infarct types as compared with Alzheimer-type dementia

The acetylcholine (ACh) and choline (Ch) concentrations in the cerebrospinal fluid were investigated in patients with vascular dementia of the Binswanger type (VDBT) or multiple small infarct type (MSID) as compared with patients with Alzheimer-type dementia (ATD). The ACh concentration in patients with ATD was found to be significantly lower than in controls (73%, p < 0.0001), and showed a significant positive correlation with dementia scale scores (rs = 0.63, p < 0.03). The Ch concentration in the CSF of ATD patients was approximately the same as in controls. In VDBT/MSID patients, the ACh concentration was significantly lower than in controls (p < 0.001) also showing a significant positive correlation with dementia scale scores (rs = 0.62, p < 0.02), but was significantly higher than in ATD patients (p < 0.001). Moreover, the Ch concentration in VDBT/MSID patients was significantly higher than in controls (p < 0.001) or ATD patients (p < 0.001). These results suggest that simultaneous determination of ACh and Ch concentrations in CSF may be useful for differentiating VDBT/MSID from ATD and that increasing the ACh level using cholinergic agents may be a beneficial therapeutic strategy for the treatment of ATD as well as VDBT/MSIT, and is worthy of further investigation.

Remarkable reduction in acetylcholine concentration in the cerebrospinal fluid from patients with Alzheimer type dementia

We determined the concentrations of acetylcholine (ACh) and choline (Ch) in the cerebrospinal fluid (CSF) of patients with Alzheimer type dementia (ATD) in comparison with controls. The ACh concentration was reduced significantly and remarkably (73%, P < 0.0002) in ATD patients and had a significant positive correlation with dementia scale scores (r = 0.82, P < 0.05). The Ch concentration was unaltered in ATD patients. These results suggest that the progressive reduction in ACh in the ATD brain may be reflected in its concentrations in the CSF.

Autonomic dysfunction in patients with dementia of the Alzheimer type

Abnormalities of the noradrenergic system have been documented in the central nervous system of patients with dementia of the Alzheimer's type (DAT). To evaluate the autonomic sympathetic system in DAT, we measured lying and standing blood pressure (BP), pulse, and plasma epinephrine (E) and norepinephrine (NE) in 60 DAT patients (mean age +/- SD = 65 +/- 8 years), and 20 normal elderly controls. DAT patients had normal baseline findings (BP, pulse, NE, and E). Upon standing, plasma NE and E significantly increased in both DAT patients and controls, without group differences. However, the systolic BP response to standing was reduced in DAT patients compared with the normal controls (repeated measures ANOVA, p < 0.01). This impaired response of the systolic BP on standing was particularly evident in DAT patients with symptoms of depression. Severely impaired DAT patients did not differ in E, NE, BP, pulse, or in orthostatic changes from mild-to-moderately impaired patients. These results suggest that the sympathetic response to the stress of standing is functionally impaired in DAT. This deficit was especially evident when DAT was accompanied by depression, consistent with prior studies in non-demented depressed patients.