Preliminary findings of high-dose thiamine in dementia of Alzheimer's type

Efficacy of high thiamine dosage in treating patients with biotin thiamine responsive basal ganglia disease: a two case reports

BACKGROUND

Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare, autosomal recessive neurometabolic disorder caused by mutations in the SLC19A3 gene and characterized by recurrent sub-acute episodes of encephalopathy. Patients with BTBGD have classical neuroimaging findings and a dramatic response to high doses of thiamine.

OBJECTIVE

To highlight the advantages of administering a higher dose of thiamine for patients with BTBGD who have not shown improvement with the standard recommended dosage.

RESULTS

Herein, we report on two Saudi girls with classical clinical and radiological findings of BTBGD. Hallmark symptoms in these patients included an acute onset of ataxia, tremor, slurred speech, dystonia, and dysphagia. The initial routine laboratory workups were unremarkable. Brain magnetic resonance imaging revealed extensive hyperintense signals in the bilateral basal ganglia, which suggested the diagnosis of a BTBGD. Hence started empirically on biotin 10 mg/kg/day and thiamine 40 mg/kg/day, but there was no noticeable improvement. After increasing the thiamine to 75 mg/kg/day the patients started to improve significantly. Genetic testing was requested and came positive for the mutation of the SLC19A3 gene. After two months of initiating the management, thiamine was reduced to 30 mg/kg/day. Subsequent follow-ups showed complete improvement in their condition with no apparent long-term sequel or relapse.

CONCLUSION

we conclude that administration of thiamine at a dosage of up to 40 mg/kg/day may not be sufficient in treating certain patients with BTBGD. Thus, considering a significantly higher dosage could potentially contribute to achieving remission.

Discovery of thiazole salt AChE inhibitors and development of thiamine disulfide prodrugs targeting the central nervous system

The selective AChE inhibitor donepezil has been approved by the FDA as a first-line drug for the treatment of mild to moderate AD. However, many peripheral side effects were observed in patients taking donepezil. Our main objective here is to provide insight into the opportunities and challenges associated with development of AChE inhibitors with high brain exposure and low peripheral side effects. In this study, we have for the first time revealed a series of novel thiazole salt AChE inhibitors, which exhibit a nanomolar inhibitory effect on human AChE. We further developed thiamine disulfide prodrugs based on optimized thiazole salt AChE inhibitors, which are reduced in the brain to form thiazole salt AChE inhibitors. In vivo experiments have confirmed that the representative prodrug Tap4 (i.p., 10 mg/kg) can be converted into the thiazole salt AChE inhibitor Tat2 and shows high brain exposure, reaching 500 ng/g. Further, the inhibitory effect of the prodrug Tap4 on AChE is obviously stronger in the brain than that on intestinal AChE of ICR mice. Our study provides a possible basis for centrally targeted thiazole salt inhibitors in the treatment of neurodegenerative diseases.

Mitochondrial Dysfunction and Neurodegenerative Disorders: Role of Nutritional Supplementation

Mitochondrial dysfunction has been implicated in the pathogenesis of a number of neurodegenerative disorders, including Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, multisystem atrophy, and progressive supranuclear palsy. This article is concerned specifically with mitochondrial dysfunction as defined by reduced capacity for ATP production, the role of depleted levels of key nutritionally related metabolites, and the potential benefit of supplementation with specific nutrients of relevance to normal mitochondrial function in the above neurodegenerative disorders. The article provides a rationale for a combination of CoQ10, B-vitamins/NADH, L-carnitine, vitamin D, and alpha-lipoic acid for the treatment of the above neurodegenerative disorders.

Pharmacological thiamine levels as a therapeutic approach in Alzheimer's disease

of the study.

Supplemental thiamine as a practical, potential way to prevent Alzheimer's disease from commencing

It is better to attempt stopping Alzheimer's disease (AD) before it starts than trying to cure it after it has developed. A cerebral scan showing deposition of either amyloid or tau identifies those elderly persons whose cognition is currently normal but who are at risk of subsequent cognitive loss that may develop into AD. Synaptic hypometabolism is usually present in such at-risk persons. Although inadequate adenosine triphosphate (ATP) may cause synaptic hypometabolism, that may not be the entire cause because, in fact, measurements in some of the at-risk persons have shown normal ATP levels. Thiamine deficiency is often seen in elderly, ambulatory persons in whom thiamine levels correlate with Mini-Mental State Examination scores. Thiamine deficiency has many consequences including hypometabolism, mitochondrial depression, oxidative stress, lactic acidosis and cerebral acidosis, amyloid deposition, tau deposition, synaptic dysfunction and abnormal neuro-transmission, astrocyte function, and blood brain barrier integrity, all of which are features of AD. Although the clinical benefits of administering supplementary thiamine to patients with AD or mild cognitive impairment have been mixed, it is more likely to succeed at preventing the onset of cognitive loss if administered at an earlier time, when the number of aberrant biochemical pathways is far fewer. Providing a thiamine supplement to elderly persons who still have normal cognition but who have deposition of either amyloid or tau, may prevent subsequent cognitive loss and eventual dementia. A clinical trial is needed to validate that possibility.

Mitochondrial medicine therapies: rationale, evidence, and dosing guidelines

PURPOSE OF REVIEW

Primary mitochondrial disease is a highly heterogeneous but collectively common inherited metabolic disorder, affecting at least one in 4300 individuals. Therapeutic management of mitochondrial disease typically involves empiric prescription of enzymatic cofactors, antioxidants, and amino acid and other nutrient supplements, based on biochemical reasoning, historical experience, and consensus expert opinion. As the field continues to rapidly advance, we review here the preclinical and clinical evidence, and specific dosing guidelines, for common mitochondrial medicine therapies to guide practitioners in their prescribing practices.

RECENT FINDINGS

Since publication of Mitochondrial Medicine Society guidelines for mitochondrial medicine therapies management in 2009, data has emerged to support consideration for using additional therapeutic agents and discontinuation of several previously used agents. Preclinical animal modeling data have indicated a lack of efficacy for vitamin C as an antioxidant for primary mitochondrial disease, but provided strong evidence for vitamin E and N-acetylcysteine. Clinical data have suggested L-carnitine may accelerate atherosclerotic disease. Long-term follow up on L-arginine use as prophylaxis against or acute treatment for metabolic strokes has provided more data supporting its clinical use in individuals with mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome and Leigh syndrome. Further, several precision therapies have been developed for specific molecular causes and/or shared clinical phenotypes of primary mitochondrial disease.

SUMMARY

We provide a comprehensive update on mitochondrial medicine therapies based on current evidence and our single-center clinical experience to support or refute their use, and provide detailed dosing guidelines, for the clinical management of mitochondrial disease. The overarching goal of empiric mitochondrial medicines is to utilize therapies with favorable benefit-to-risk profiles that may stabilize and enhance residual metabolic function to improve cellular resiliency and slow clinical disease progression and/or prevent acute decompensation.

Thiamine mimetics sulbutiamine and benfotiamine as a nutraceutical approach to anticancer therapy

Malignant cells frequently demonstrate an oncogenic-driven reliance on glycolytic metabolism to support their highly proliferative nature. Overexpression of pyruvate dehydrogenase kinase (PDK) may promote this unique metabolic signature of tumor cells by inhibiting mitochondrial function. PDKs function to phosphorylate and inhibit pyruvate dehydrogenase (PDH) activity. Silencing of PDK expression has previously been shown to restore mitochondrial function and reduce tumor cell proliferation. High dose Vitamin B1, or thiamine, possesses antitumor properties related to its capacity to reduce PDH phosphorylation and promote its enzymatic activity, presumably through PDK inhibition. Though a promising nutraceutical approach for cancer therapy, thiamine's low bioavailability may limit clinical effectiveness. Here, we have demonstrated exploiting the commercially available lipophilic thiamine analogs sulbutiamine and benfotiamine increases thiamine's anti-cancer effect in vitro. Determined by crystal violet proliferation assays, both sulbutiamine and benfotiamine reduced thiamine's millimolar IC50 value to micromolar equivalents. HPLC analysis revealed that sulbutiamine and benfotiamine significantly increased intracellular thiamine and TPP concentrations in vitro, corresponding with reduced levels of PDH phosphorylation. Through an ex vitro kinase screen, thiamine's activated cofactor form thiamine pyrophosphate (TPP) was found to inhibit the function of multiple PDK isoforms. Attempts to maximize intracellular TPP by exploiting thiamine homeostasis gene expression resulted in enhanced apoptosis in tumor cells. Based on our in vitro evaluations, we conclude that TPP serves as the active species mediating thiamine's inhibitory effect on tumor cell proliferation. Pharmacologic administration of benfotiamine, but not sulbutiamine, reduced tumor growth in a subcutaneous xenograft mouse model. It remains unclear if benfotiamine's effects in vivo are associated with PDK inhibition or through an alternative mechanism of action. Future work will aim to define the action of lipophilic thiamine mimetics in vivo in order to translate their clinical usefulness as anticancer strategies.

Implications of Successful Symptomatic Treatment in Parkinson's Disease for Therapeutic Strategies of Alzheimer's Disease

Alzheimer's disease (AD) has been a devastating neurodegenerative disorder and lacks effective treatment to improve the prognosis for patients. Symptomatic treatment for AD mainly includes two categories: Acetylcholinesterase inhibitors and the N-methyl-d-aspartate (NMDA) receptor antagonist (memantine). They cannot significantly improve the quality of life and extend survival time for AD patients. Worse, almost all clinical trials for disease-modifying drugs have failed, and the reduction of brain β-amyloid (Aβ) deposition by multiple approaches, including inhibitors of β- or γ-secretase, vaccines, and antibodies against Aβ deposition, was found to have little effect on AD progression. A new therapeutic strategy for AD is urgently needed. Parkinson's disease also is a neurodegenerative disease having no effective treatment for modifying the disease. Nevertheless, successful symptomatic treatment using the combined therapies of l-DOPA supplement and modulators of l-DOPA metabolism greatly improves the prognosis for PD patients; the average survival time of the patient has been extended from 3-4 years to 10-15 years although dopaminergic neurons are still progressively decreasing. This provides useful implications for AD therapeutic strategies. AD patients manifest global cognitive decline, prominently represented by memory deficit, especially in the early stages of the disease. Further, the degree of decreased cognitive abilities correlates with cholinergic dysfunction and the hypometabolism of glucose, the dominant energy fuel for brain. Thus, the amelioration of brain cholinergic function and brain energy metabolism may be effective treatment to improve cognitive abilities of AD patients. Here, we highlighted the explorations of symptomatic therapeutics through modulating brain cholinergic function and energy metabolism in AD.

Benfotiamine treatment activates the Nrf2/ARE pathway and is neuroprotective in a transgenic mouse model of tauopathy

Impaired glucose metabolism, decreased levels of thiamine and its phosphate esters, and reduced activity of thiamine-dependent enzymes, such as pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and transketolase occur in Alzheimer's disease (AD). Thiamine deficiency exacerbates amyloid beta (Aβ) deposition, tau hyperphosphorylation and oxidative stress. Benfotiamine (BFT) rescued cognitive deficits and reduced Aβ burden in amyloid precursor protein (APP)/PS1 mice. In this study, we examined whether BFT confers neuroprotection against tau phosphorylation and the generation of neurofibrillary tangles (NFTs) in the P301S mouse model of tauopathy. Chronic dietary treatment with BFT increased lifespan, improved behavior, reduced glycated tau, decreased NFTs and prevented death of motor neurons. BFT administration significantly ameliorated mitochondrial dysfunction and attenuated oxidative damage and inflammation. We found that BFT and its metabolites (but not thiamine) trigger the expression of Nrf2/antioxidant response element (ARE)-dependent genes in mouse brain as well as in wild-type but not Nrf2-deficient fibroblasts. Active metabolites were more potent in activating the Nrf2 target genes than the parent molecule BFT. Docking studies showed that BFT and its metabolites (but not thiamine) bind to Keap1 with high affinity. These findings demonstrate that BFT activates the Nrf2/ARE pathway and is a promising therapeutic agent for the treatment of diseases with tau pathology, such as AD, frontotemporal dementia and progressive supranuclear palsy.

High thiamine diphosphate level as a protective factor for Alzheimer's disease

Objectives Thiamine diphosphate (TDP) is an indispensable coenzyme for three key enzymes in glucose metabolism. Reduced TDP levels in patients with Alzheimer's disease (AD) has been widely demonstrated and is a diagnostic biomarker for the disease. In this study, we further explored the correlation between altered TDP metabolism and AD along with other risk factors. Methods A 1:1 case-control study was employed with 90 AD patients and 90 control subjects with normal-range cognitive abilities as assayed by the Mini Mental Status Evaluation. Age (≤2 years variation), gender, and educational background were strictly matched. Levels of the main thiamine metabolites in whole blood samples, including TDP, thiamine monophosphate, and thiamine, were assayed using high-performance liquid chromatography. Apolipoprotein E genotypes, haemoglobin, and several metabolic factors (fasting glucose, uric acid, triglyceride, and total cholesterol) associated with AD were also measured. Results The odds ratio of TDP level for AD was 0.95 (with TDP level as a continuous variable) or 0.09 (with TDP level as a dichotomized variable with a cut-off value of 99.48 nmol/L). Blood TDP levels were significantly decreased in female AD patients compared to male AD patients. No correlations were identified between TDP levels and several metabolic factors (fasting glucose, uric acid, triglyceride, and total cholesterol). Conclusions TDP is a protective factor for AD and its protective efficacy may be independent of other metabolic factors. The difference of TDP levels between genders may be another possible explanation for the higher prevalence of AD in females.

Enhanced Activities of Blood Thiamine Diphosphatase and Monophosphatase in Alzheimer's Disease

Background

Thiamine metabolites and activities of thiamine-dependent enzymes are impaired in Alzheimer’s disease (AD).

Objective

To clarify the mechanism for the reduction of thiamine diphosphate (TDP), an active form of thiamine and critical coenzyme of glucose metabolism, in AD.

Methods

Forty-five AD patients clinically diagnosed and 38 age- and gender-matched control subjects without dementia were voluntarily recruited. The contents of blood TDP, thiamine monophosphate (TMP), and thiamine, as well as the activities of thiamine diphosphatase (TDPase), thiamine monophosphatase (TMPase), and thiamine pyrophosphokinase (TPK), were assayed by high performance liquid chromatography.

Results

Blood TDP contents of AD patients were significantly lower than those in control subjects (79.03 ± 23.24 vs. 127.60 ± 22.65 nmol/L, P<0.0001). Activities of TDPase and TMPase were significantly enhanced in AD patients than those in control subjects (TDPase: 1.24 ± 0.08 vs. 1.00 ± 0.04, P < 0.05; TMPase: 1.22 ± 0.04 vs. 1.00 ± 0.06, P < 0.01). TPK activity remained unchanged in AD as compared with that in control (0.93 ± 0.04 vs. 1.00 ± 0.04, P > 0.05). Blood TDP levels correlated negatively with TDPase activities (r = -0.2576, P = 0.0187) and positively with TPK activities (r = 0.2426, P = 0.0271) in all participants.

Conclusion

Enhanced TDPase and TMPase activities may contribute to the reduction of TDP level in AD patients. The results imply that an imbalance of phosphorylation-dephosphorylation related to thiamine and glucose metabolism may be a potential target for AD prevention and therapy.

Thiamine Deficiency and Neurodegeneration: the Interplay Among Oxidative Stress, Endoplasmic Reticulum Stress, and Autophagy

Thiamine (vitamin B1) is an essential nutrient and indispensable for normal growth and development of the organism due to its multilateral participation in key biochemical and physiological processes. Humans must obtain thiamine from their diet since it is synthesized only in bacteria, fungi, and plants. Thiamine deficiency (TD) can result from inadequate intake, increased requirement, excessive deletion, and chronic alcohol consumption. TD affects multiple organ systems, including the cardiovascular, muscular, gastrointestinal, and central and peripheral nervous systems. In the brain, TD causes a cascade of events including mild impairment of oxidative metabolism, neuroinflammation, and neurodegeneration, which are commonly observed in neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Thiamine metabolites may serve as promising biomarkers for neurodegenerative diseases, and thiamine supplementations exhibit therapeutic potential for patients of some neurodegenerative diseases. Experimental TD has been used to model aging-related neurodegenerative diseases. However, to date, the cellular and molecular mechanisms underlying TD-induced neurodegeneration are not clear. Recent research evidence indicates that TD causes oxidative stress, endoplasmic reticulum (ER) stress, and autophagy in the brain, which are known to contribute to the pathogenesis of various neurodegenerative diseases. In this review, we discuss the role of oxidative stress, ER stress, and autophagy in TD-mediated neurodegeneration. We propose that it is the interplay of oxidative stress, ER stress, and autophagy that contributes to TD-mediated neurodegeneration.

Long-term treatment with thiamine as possible medical therapy for Friedreich ataxia

Thiamine (vitamin B1) is a cofactor of fundamental enzymes of cell energetic metabolism; its deficiency causes disorders affecting both the peripheral and central nervous system. Previous studies reported low thiamine levels in cerebrospinal fluid and pyruvate dehydrogenase dysfunction in Friedreich ataxia (FRDA). We investigated the effect of long-term treatment with thiamine in FRDA, evaluating changes in neurological symptoms, echocardiographic parameters, and plasma FXN mRNA levels. Thirty-four consecutive FRDA patients have been continuously treated with intramuscular thiamine 100 mg twice a week and have been assessed with the Scale for the Assessment and Rating of Ataxia (SARA) at baseline, after 1 month, and then every 3 months during treatment. Thiamine administration ranged from 80 to 930 days and was effective in improving total SARA scores from 26.6 ± 7.7 to 21.5 ± 6.2 (p < 0.02). Moreover, deep tendon reflexes reappeared in 57 % of patients with areflexia at baseline, and swallowing improved in 63 % of dysphagic patients. Clinical improvement was stable in all patients, who did not show worsening even after 2 years of treatment. In a subgroup of 13 patients who performed echocardiogram before and during treatment, interventricular septum thickness reduced significantly (p < 0.02). Frataxin mRNA blood levels were modestly increased in one-half of treated patients. We suppose that a focal thiamine deficiency may contribute to a selective neuronal damage in the areas involved in FRDA. Further studies are mandatory to evaluate thiamine role on FXN regulation, to exclude placebo effect, to verify our clinical results, and to confirm restorative and neuroprotective action of thiamine in FRDA.

Vitamin B1 (thiamine) and dementia

The earliest and perhaps best example of an interaction between nutrition and dementia is related to thiamine (vitamin B1). Throughout the last century, research showed that thiamine deficiency is associated with neurological problems, including cognitive deficits and encephalopathy. Multiple similarities exist between classical thiamine deficiency and Alzheimer's disease (AD) in that both are associated with cognitive deficits and reductions in brain glucose metabolism. Thiamine-dependent enzymes are critical components of glucose metabolism that are reduced in the brains of AD patients and by thiamine decline, and a decrease in their levels could account for the reduction in glucose metabolism. In preclinical models, reduced thiamine can drive AD-like abnormalities, including memory deficits, neuritic plaques, and hyperphosphorylation of tau. Furthermore, excess thiamine diminishes AD-like pathologies. In addition to dietary deficits, drugs or other manipulations that interfere with thiamine absorption can cause thiamine deficiency. Elucidating the reasons why the brains of AD patients are functionally thiamine deficient and determining the effects of thiamine restoration may provide critical information to help treat patients with AD.

Long-Term Treatment with High-Dose Thiamine in Parkinson Disease: An Open-Label Pilot Study

OBJECTIVES

To investigate the potential clinical, restorative, and neuroprotective effects of long-term treatment with thiamine in Parkinson disease (PD).

DESIGN

Observational open-label pilot study.

SETTING

Outpatient neurologic rehabilitation clinic.

PATIENTS AND METHODS

Starting in June 2012, we have recruited 50 patients with PD (33 men and 17 women; mean age, 70.4 ± 12.9 years; mean disease duration, 7.3 ± 6.7 years). All the patients were assessed at baseline with the Unified Parkinson's Disease Rating Scale (UPDRS) and the Fatigue Severity Scale (FSS) and began treatment with 100 mg of thiamine administered intramuscularly twice a week, without any change to personal therapy. All the patients were re-evaluated after 1 month and then every 3 months during treatment.

RESULTS

Thiamine treatment led to significant improvement of motor and nonmotor symptoms: mean UPDRS scores (parts I-IV) improved from 38.55 ± 15.24 to 18.16 ± 15.08 (p = 2.4 × 10(-14), t test for paired data) within 3 months and remained stable over time; motor UPDRS part III score improved from 22.01 ± 8.57 to 9.92 ± 8.66 (p = 3.1 × 10(-22)). Some patients with a milder phenotype had complete clinical recovery. FSS scores, in six patients who had fatigue, improved from 53.00 ± 8.17 to 23.60 ± 7.77 (p < 0.0001, t test for paired data). Follow-up duration ranged from 95 to 831 days (mean, 291.6 ± 207.2 days).

CONCLUSIONS

Administration of parenteral high-dose thiamine was effective in reversing PD motor and nonmotor symptoms. The clinical improvement was stable over time in all the patients. From our clinical evidence, we hypothesize that a dysfunction of thiamine-dependent metabolic processes could cause selective neural damage in the centers typically affected by this disease and might be a fundamental molecular event provoking neurodegeneration. Thiamine could have both restorative and neuroprotective action in PD.

Role of dietary protein and thiamine intakes on cognitive function in healthy older people: a systematic review

The effectiveness of nutritional interventions to prevent and maintain cognitive functioning in older adults has been gaining interest due to global population ageing. A systematic literature review was conducted to obtain and appraise relevant studies on the effects of dietary protein or thiamine on cognitive function in healthy older adults. Studies that reported on the use of nutritional supplementations and/or populations with significant cognitive impairment were excluded. Seventeen eligible studies were included. Evidence supporting an association between higher protein and/or thiamine intakes and better cognitive function is weak. There was no evidence to support the role of specific protein food sources, such as types of meat, on cognitive function. Some cross-sectional and case-control studies reported better cognition in those with higher dietary thiamine intakes, but the data remains inconclusive. Adequate protein and thiamine intake is more likely associated with achieving a good overall nutritional status which affects cognitive function rather than single nutrients. A lack of experimental studies in this area prevents the translation of these dietary messages for optimal cognitive functioning and delaying the decline in cognition with advancing age.

Malnutrition-induced Wernicke's encephalopathy following a water-only fasting diet

BACKGROUND

Wernicke's encephalopathy is a critical condition of neurological dysfunction resulting from a deficiency in thiamine. Chronic alcoholism is recognized as the most common cause of Wernicke's encephalopathy, but other causes, including fasting/starvation and malnutrition, have been documented within the scientific literature. These causes may not be readily recognized by healthcare professionals and may lead to Wernicke's encephalopathy being overlooked as a diagnosis when a nonalcoholic patient presents with classic signs and symptoms of the disorder.

MATERIALS AND METHODS

A narrative review of thiamine and its relationship to the development, diagnosis, and treatment of Wernicke's encephalopathy is presented based on a review of evidence-based guidelines and published research. To heighten awareness of the development of Wernicke's encephalopathy in fasted/starved and malnourished patients and to contribute to the scientific body of knowledge for the identification and management of Wernicke's encephalopathy in these patients, the clinical course and treatment of an adult woman who developed Wernicke's encephalopathy following a 40-day water-only fasting diet is outlined.

RESULTS

Clinical suspicion was required to identify the patient's condition and initiate immediate intervention through parenteral thiamine administration. Oral thiamine supplementation of 100 to 800 mg per day for 6 months was required to aid recovery.

OUTCOMES

The patient's clinical course and response to treatment illustrate the necessity for clinical awareness and suspicion of Wernicke's encephalopathy among healthcare professionals, timely and adequate parenteral thiamine administration, and oral thiamine supplementation at therapeutic doses to correct the nutrient deficiency, halt the progression of Wernicke's encephalopathy, and promote recovery.

Risk Profiles of Alzheimer Disease

Alzheimer disease (AD) is a dementing, neurodegenerative disorder that affects approximately 500,000 Canadians and its prevalence is expected to double over the next 30 years. Although several medications may temporarily augment cognitive abilities in AD, there presently exists no proven method to avoid the inevitable clinical deterioration in this devastating condition. The delineation of risk factors for the development of AD offers hope for the advent of effective prevention or interventions that might retard the onset of symptoms. In this article, we provide a comprehensive review of midlife risk factors implicated in the etiopathogenesis of sporadic AD. Although some risk factors are heritable and largely beyond our control, others are determined by lifestyle or environment and are potentially modifiable. In a companion paper, we introduce the concept of an Alzheimer Risk Assessment Clinic for ascertainment and mitigation of these and other putative dementia risk factors in middle-aged adults.

Interactions of endoplasmic reticulum and mitochondria Ca(2+) stores with capacitative calcium entry

Thiamine dependent enzymes are diminished in Alzheimer's disease (AD). Thiamine deficiency in vitro and in rodents is a useful model of this reduction. Thiamine interacts with cellular calcium stores. To directly test the relevance of the thiamine dependent changes to dynamic processes in AD, the interactions must be studied in cells from patients with AD. These studies employed fibroblasts. Mitochondrial dysfunction including reductions in thiamine dependent enzymes and abnormalities in calcium homeostasis and oxidative processes occur in fibroblasts from Alzheimer's Disease (AD) patients. Bombesin-releasable calcium stores (BRCS) from the endoplasmic reticulum (ER) are exaggerated in fibroblasts from patients with AD bearing a presenilin-1 (PS-1) mutation and in control fibroblasts treated with oxidants. ER calcium regulates calcium entry into the cell through capacitative calcium entry (CCE), which is reduced in fibroblasts and neurons from mice bearing PS-1 mutations. Under physiological conditions, mitochondria and ER play important and interactive roles in the regulation of Ca(2+) homeostasis. Thus, the interactions of mitochondria and oxidants with CCE were tested. Inhibition of ER Ca(2+)-ATPase by cyclopiazonic acid (CPA) stimulates CCE. CPA-induced CCE was diminished by inhibition of mitochondrial Ca(2+) export (-60%) or import (-40%). Different aspects of mitochondrial Ca(2+) coupled to CPA-induced-CCE were sensitive to select oxidants. The effects were very different when CCE was examined in the presence of InsP3, a physiological regulator of ER calcium release, and subsequent CCE. CCE under these conditions was only mildly reduced (20-25%) by inhibition of mitochondrial Ca(2+) export, and inhibition of mitochondrial Ca(2+) uptake exaggerated CCE (+53%). However, t-BHP reversed both abnormalities. The results suggest that in the presence of InsP3, mitochondria buffer the local Ca(2+) released from ER following rapid activation of InsP3R and serve as a negative feedback to the CCE. The results suggest that mitochondrial Ca(2+) modifies the depletion and refilling mechanism of ER Ca(2+) stores.

Vitamin B1 derived blue and green fluorescent carbon nanoparticles for cell-imaging application

A carbon-based fluorescent nanoparticle is considered to be a new generation nontoxic nanoprobe suitable for various bioimaging and sensing applications. However, the synthesis of such a high-quality nanoparticle is challenging, and its application potential is mostly unexplored. Here we report a vitamin B1 carbonization-based approach for blue and green fluorescent carbon nanoparticles of <10 nm size with a fluorescence quantum of up to 76%. We found that carbonization of vitamin B1 in the presence of phosphate salt at ∼90-130 °C for about 2 h produces highly fluorescent carbon nanoparticles of 1-6 nm size. The particle size and fluorescence property can be controlled by varying the reaction temperature and nature of phosphate salt. Elemental analysis shows the incorporation of a large percentage (up to 48 wt %) of other elements (such as nitrogen, oxygen, phophorus, and sulfur) in the carbon matrix. The chemical structure of vitamin B1 (thiamine) is unique in a sense that it consists of a large number of heteroatoms along with unsaturated bonds and offers low-temperature carbonization with the formation of a nanoparticle having an optimum ratio of sp(2) and sp(3) carbon atoms. These carbon nanoparticles have high colloidal stability and stable fluorescence and have been used as fluorescent imaging probes.

High-dose vitamin B1 reduces proliferation in cancer cell lines analogous to dichloroacetate

PURPOSE

The dichotomous effect of thiamine supplementation on cancer cell growth is characterized by growth stimulation at low doses and growth suppression at high doses. Unfortunately, how thiamine reduces cancer cell proliferation is currently unknown. Recent focuses on metabolic targets for cancer therapy have exploited the altered regulation of the thiamine-dependent enzyme pyruvate dehydrogenase (PDH). Cancer cells inactivate PDH through phosphorylation by overexpression of pyruvate dehydrogenase kinases (PDKs). Inhibition of PDKs by dichloracetate (DCA) exhibits a growth suppressive effect in many cancers. Recently, it has been shown that the thiamine coenzyme, thiamine pyrophosphate reduces PDK-mediated phosphorylation of PDH. Therefore, the objective of this study was to determine whether high-dose thiamine supplementation reduces cell proliferation through a DCA-like mechanism.

METHODS

Cytotoxicity of thiamine and DCA was assessed in SK-N-BE and Panc-1 cancer cell lines. Comparative effects of high-dose thiamine and DCA on PDH phosphorylation were measured by Western blot. The metabolic impact of PDH reactivation was determined by glucose and lactate assays. Changes in the mitochondrial membrane potential, reactive oxygen species (ROS) production, and caspase-3 activation were assessed to characterize the mechanism of action.

RESULTS

Thiamine exhibited a lower IC50 value in both cell lines compared with DCA. Both thiamine and DCA reduced the extent of PDH phosphorylation, reduced glucose consumption, lactate production, and mitochondrial membrane potential. High-dose thiamine and DCA did not increase ROS, but increased caspase-3 activity.

CONCLUSION

Our findings suggest that high-dose thiamine reduces cancer cell proliferation by a mechanism similar to that described for dichloroacetate.

Reducing mitochondrial decay with mitochondrial nutrients to delay and treat cognitive dysfunction, Alzheimer's disease, and Parkinson's disease

Mitochondrial decay due to oxidative damage is a contributor to brain aging and age-related neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). One type of mitochondrial decay is oxidative modification of key mitochondrial enzymes. Enzyme dysfunction, that is due to poor binding of substrates and coenzymes may be ameliorated by supplementing adequate levels of substrates or coenzyme precursors. Such supplementation with mitochondrial nutrients (mt-nutrients) may be useful to prevent or delay mitochondrial decay, thus prevent or treat AD and PD. In the present review, we survey the literature to identify mt-nutrients that can (1) protect mitochondrial enzymes and/or stimulate enzyme activity by elevating levels of substrates and cofactors; (2) induce phase-2 enzymes to enhance antioxidant defenses; (3) scavenge free radicals and prevent oxidant production in mitochondria, and (4) repair mitochondrial membrane. Then, we discuss the relationships among mt-nutrient deficiency, mitochondrial decay, and cognitive dysfunction, and summarize available evidence suggesting an effect of mt-nutrient supplementation on AD and PD. It appears that greater effects might be obtained by longer-term administration of combinations of mt-nutrients. Thus, optimal doses of combinations of mt-nutrients to delay and repair mitochondrial decay could be a strategy for preventing and treating cognitive dysfunction, including AD and PD.

Decoding Alzheimer's disease from perturbed cerebral glucose metabolism: implications for diagnostic and therapeutic strategies

Alzheimer's disease (AD) is an age-related devastating neurodegenerative disorder, which severely impacts on the global economic development and healthcare system. Though AD has been studied for more than 100 years since 1906, the exact cause(s) and pathogenic mechanism(s) remain to be clarified. Also, the efficient disease-modifying treatment and ideal diagnostic method for AD are unavailable. Perturbed cerebral glucose metabolism, an invariant pathophysiological feature of AD, may be a critical contributor to the pathogenesis of this disease. In this review, we firstly discussed the features of cerebral glucose metabolism in physiological and pathological conditions. Then, we further reviewed the contribution of glucose transportation abnormality and intracellular glucose catabolism dysfunction in AD pathophysiology, and proposed a hypothesis that multiple pathogenic cascades induced by impaired cerebral glucose metabolism could result in neuronal degeneration and consequently cognitive deficits in AD patients. Among these pathogenic processes, altered functional status of thiamine metabolism and brain insulin resistance are highly emphasized and characterized as major pathogenic mechanisms. Finally, considering the fact that AD patients exhibit cerebral glucose hypometabolism possibly due to impairments of insulin signaling and altered thiamine metabolism, we also discuss some potential possibilities to uncover diagnostic biomarkers for AD from abnormal glucose metabolism and to develop drugs targeting at repairing insulin signaling impairment and correcting thiamine metabolism abnormality. We conclude that glucose metabolism abnormality plays a critical role in AD pathophysiological alterations through the induction of multiple pathogenic factors such as oxidative stress, mitochondrial dysfunction, and so forth. To clarify the causes, pathogeneses and consequences of cerebral hypometabolism in AD will help break the bottleneck of current AD study in finding ideal diagnostic biomarker and disease-modifying therapy.

Differentially expressed genes in Hirudo medicinalis ganglia after acetyl-L-carnitine treatment

Acetyl-L-carnitine (ALC) is a naturally occurring substance that, when administered at supra-physiological concentration, is neuroprotective. It is involved in membrane stabilization and in enhancement of mitochondrial functions. It is a molecule of considerable interest for its clinical application in various neural disorders, including Alzheimer's disease and painful neuropathies. ALC is known to improve the cognitive capability of aged animals chronically treated with the drug and, recently, it has been reported that it impairs forms of non-associative learning in the leech. In the present study the effects of ALC on gene expression have been analyzed in the leech Hirudo medicinalis. The suppression subtractive hybridisation methodology was used for the generation of subtracted cDNA libraries and the subsequent identification of differentially expressed transcripts in the leech nervous system after ALC treatment. The method detects differentially but also little expressed transcripts of genes whose sequence or identity is still unknown. We report that a single administration of ALC is able to modulate positively the expression of genes coding for functions that reveal a lasting effect of ALC on the invertebrate, and confirm the neuroprotective and neuromodulative role of the substance. In addition an important finding is the modulation of genes of vegetal origin. This might be considered an instance of ectosymbiotic mutualism.

Abnormal thiamine-dependent processes in Alzheimer's Disease. Lessons from diabetes

Reduced glucose metabolism is an invariant feature of Alzheimer's Disease (AD) and an outstanding biomarker of disease progression. Glucose metabolism may be an attractive therapeutic target, whether the decline initiates AD pathophysiology or is a critical component of a cascade. The cause of cerebral regional glucose hypometabolism remains unclear. Thiamine-dependent processes are critical in glucose metabolism and are diminished in brains of AD patients at autopsy. Further, the reductions in thiamine-dependent processes are highly correlated to the decline in clinical dementia rating scales. In animal models, thiamine deficiency exacerbates plaque formation, promotes phosphorylation of tau and impairs memory. In contrast, treatment of mouse models of AD with the thiamine derivative benfotiamine diminishes plaques, decreases phosphorylation of tau and reverses memory deficits. Diabetes predisposes to AD, which suggests they may share some common mechanisms. Benfotiamine diminishes peripheral neuropathy in diabetic humans and animals. In diabetes, benfotiamine induces key thiamine-dependent enzymes of the pentose shunt to reduce accumulation of toxic metabolites including advanced glycation end products (AGE). Related mechanisms may lead to reversal of plaque formation by benfotiamine in animals. If so, the use of benfotiamine could provide a safe intervention to reverse biological and clinical processes of AD progression. This article is part of a Special Issue entitled 'Mitochondrial function and dysfunction in neurodegeneration'.

Pharmacokinetics of high-dose oral thiamine hydrochloride in healthy subjects

BACKGROUND

High dose oral thiamine may have a role in treating diabetes, heart failure, and hypermetabolic states. The purpose of this study was to determine the pharmacokinetic profile of oral thiamine hydrochloride at 100 mg, 500 mg and 1500 mg doses in healthy subjects.

METHODS

This was a randomized, double-blind, single-dose, 4-way crossover study. Pharmacokinetic measures were calculated.

RESULTS

The AUC₀₋₁₀ hr and C(max) values increased nonlinearly between 100 mg and 1500 mg. The slope of the AUC₀₋₁₀ hr vs dose, as well as the C(max) vs dose, plots are steepest at the lowest thiamine doses.

CONCLUSION

Our study demonstrates that high blood levels of thiamine can be achieved rapidly with oral thiamine hydrochloride. Thiamine is absorbed by both an active and nonsaturable passive process.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00981877.

Thiamin(e): the spark of life

One of the earliest vitamins to be discovered and synthesized, thiamin was originally spelled with an "e". The terminal "e" was dropped when it was found that it was not an amine. It is still spelled with and without the "e" depending on the text. This chapter provides a brief historical review of the association of thiamin with the ancient scourge of beriberi. It emphasizes that beriberi is the model for high calorie malnutrition because of its occurrence in predominantly white rice consuming cultures. Some of the symptomatology of this ancient scourge is described, emphasizing the difference from that seen in starvation. High calorie malnutrition, due to excessive ingestion of simple carbohydrates, is widely encountered in the U.S.A. today. Thiamin deficiency is commonly associated with this, largely because of its cofactor status in the metabolism of glucose. The biochemistry of the three phosphorylated esters of thiamin and the transporters are discussed and the pathophysiology of thiamin deficiency reviewed. The role of thiamin, and particularly its synthetic derivatives as therapeutic agents, is not fully appreciated in Western civilization and a clinical section describes some of the unusual cases described in the scientific literature and some experienced by the author. The possible role of high calorie malnutrition and related thiamin deficiency in juvenile crime is hypothesized.

Role of thiamine in Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia in elderly individuals and is associated with progressive neurodegeneration of the human neocortex. Thiamine levels and the activity of thiamine-dependent enzymes are reduced in the brains and peripheral tissues of patients with AD. Genetic studies have provided the opportunity to determine what proteins link thiamine to AD pathology (ie, transketolase, apolipoprotein E, α-1-antitrypsin, pyruvate dehydrogenase complex, p53, glycogen synthetase kinase-3β, c-Fos gene, the Sp1 promoter gene, and the poly(ADP-ribosyl) polymerase-1 gene). We reviewed the association between histopathogenesis and neurotransmitters to understand the relationship between thiamine and AD pathology. Oral thiamine trials have been shown to improve the cognitive function of patients with AD; however, absorption of thiamine is poor in elderly individuals. In the early stage of thiamine-deficient encephalopathy (Wernicke's encephalopathy), however, parental thiamine has been used successfully. Therefore, further studies are needed to determine the benefits of using parental thiamine as a treatment for AD.

Utility of imaging for nutritional intervention studies in Alzheimer's disease

Alzheimer's disease (AD) is a multi-factorial neurodegenerative disorder and the leading cause of dementia, wherein synapse loss is the strongest structural correlate with cognitive impairment. Basic research has shown that dietary supply of precursors and co-factors for synthesis of neuronal membranes enhances the formation of synapses. Daily intake of a medical food containing a mix of these nutrients for 12 weeks in humans improved memory, measured as immediate and delayed verbal recall by the Wechsler Memory Scale-revised, in patients with very mild AD (MMSE 24-26). An improvement of immediate verbal recall was noted following 24 weeks of intervention in an exploratory extension of the study. These data suggest that the intervention may improve synaptic formation and function in early AD. Here we review emerging technologies that help identify changes in pathological hallmarks in AD, including synaptic function and loss of connectivity in the early stages of AD, before cognitive and behavioural symptoms are observable. These techniques include the detection of specific biomarkers in the cerebrospinal fluid, as well as imaging procedures such as fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), amyloid PET, structural/functional magnetic resonance imaging, diffusion tensor imaging, magnetoencephalography (MEG) and electroencephalography (EEG). Such techniques can provide new insights into the functional and structural changes in the brain over time, and may therefore help to develop more effective AD therapies. In particular, nutritional intervention studies that target synapse formation and function may benefit from these techniques, especially FDG-PET and EEG/MEG employed in the preclinical or early stages of the disease.

A mitocentric view of Alzheimer's disease suggests multi-faceted treatments

Alzheimer's disease (AD) is defined by senile plaques made of amyloid-beta peptide (Abeta), neurofibrillary tangles made of hyperphosphorylated tau proteins, and memory deficits. Thus, the events initiating the cascade leading to these end points may be more effective therapeutic targets than treating each facet individually. In the small percentage of cases of AD that are genetic (or animal models that reflect this form of AD), the factor initiating AD is clear (e.g., genetic mutations lead to high Abeta1-42 or hyperphosphorylated tau proteins). In the vast majority of AD cases, the cause is unknown. Substantial evidence now suggests that abnormalities in glucose metabolism/mitochondrial function/oxidative stress (GMO) are an invariant feature of AD and occur at an early stage of the disease process in both genetic and non-genetic forms of AD. Indeed, decreases in brain glucose utilization are diagnostic for AD. Changes in calcium homeostasis also precede clinical manifestations of AD. Abnormal GMO can lead to plaques, tangles, and the calcium abnormalities that accompany AD. Abnormalities in GMO diminish the ability of the brain to adapt. Therapies targeting mitochondria may ameliorate abnormalities in plaques, tangles, calcium homeostasis, and cognition that comprise AD.

Thiamine and oxidants interact to modify cellular calcium stores

Diminished thiamine (vitamin B1) dependent processes and oxidative stress accompany Alzheimer's disease (AD). Thiamine deficiency in animals leads to oxidative stress. These observations suggest that thiamin may act as an antioxidant. The current experiments first tested directly whether thiamin could act as an antioxidant, and then examined the physiological relevance of the antioxidant properties on oxidant sensitive, calcium dependent processes that are altered in AD. The first group of experiments examined whether thiamin could diminish reactive oxygen species (ROS) or reactive nitrogen species (RNS) produced by two very divergent paradigms. Dose response curves determined the concentrations of t-butyl-hydroperoxide (t-BHP) (ROS production) or 3-morpholinosydnonimine ((SIN-1) (RNS production) to induce oxidative stress within cells. Concentrations of thiamine that reduced the RNS in cells did not diminish the ROS. The second group of experiments tested whether thiamine alters oxidant sensitive aspects of calcium regulation including endoplasmic reticulum (ER) calcium stores and capacitative calcium entry (CCE). Thiamin diminished ER calcium considerably, but did not alter CCE. Thiamine did not alter the actions of ROS on ER calcium or CCE. On the other hand, thiamine diminished the effect of RNS on CCE. These data are consistent with thiamine diminishing the actions of the RNS, but not ROS, on physiological targets. Thus, both experimental approaches suggest that thiamine selectively alters RNS. Additional experiments are required to determine whether diminished thiamine availability promotes oxidative stress in AD or whether the oxidative stress in AD brain diminishes thiamine availability to thiamine dependent processes.

Is B vitamins deficiency associated with prevalence of Alzheimer's disease in Cuban elderly?

Alzheimer's disease (AD), is a major public health problem among the elderly in industrialized countries and a growing problem in developing countries. In Cuba, 14,6% of the population is older than 60 years. The AD prevalence in Cuba lies between 5,13-7,14%. Several studies have shown the relationship between the low nutritional status of B vitamins, hyperhomocysteinaemia with loss of neuro-cognitive function and AD. In studies during the epidemic neuropathy that affected Cuba between 1992-1993, B vitamins deficiency and smoking habits were strongly associated with the epidemic. Some studies in healthy adults and elderly after this epidemic have shown a sub-clinical deficiency of some B vitamins and a high prevalence of infection by Helicobacter pylori. The possibility that B vitamin deficiencies could be an additional risk factor for the high prevalence of the AD in Cuba is discussed.

A review of the biochemistry, metabolism and clinical benefits of thiamin(e) and its derivatives

Thiamin(e), also known as vitamin B1, is now known to play a fundamental role in energy metabolism. Its discovery followed from the original early research on the ‘anti-beriberi factor’ found in rice polishings. After its synthesis in 1936, it led to many years of research to find its action in treating beriberi, a lethal scourge known for thousands of years, particularly in cultures dependent on rice as a staple. This paper refers to the previously described symptomatology of beriberi, emphasizing that it differs from that in pure, experimentally induced thiamine deficiency in human subjects. Emphasis is placed on some of the more unusual manifestations of thiamine deficiency and its potential role in modern nutrition. Its biochemistry and pathophysiology are discussed and some of the less common conditions associated with thiamine deficiency are reviewed. An understanding of the role of thiamine in modern nutrition is crucial in the rapidly advancing knowledge applicable to Complementary Alternative Medicine. References are given that provide insight into the use of this vitamin in clinical conditions that are not usually associated with nutritional deficiency. The role of allithiamine and its synthetic derivatives is discussed. Thiamine plays a vital role in metabolism of glucose. Thus, emphasis is placed on the fact that ingestion of excessive simple carbohydrates automatically increases the need for this vitamin. This is referred to as high calorie malnutrition.

Effectiveness of Nutritional Supplements on Cognitive Functioning in Elderly Persons: A Systematic Review

BACKGROUND

The effectiveness of nutritional supplementation in improving cognitive functioning is evaluated in elderly people.

METHODS

The authors systematically reviewed randomized controlled trials that compared nutritional supplementation with a placebo treatment. Trials were identified from a MEDLINE search and from reference lists of identified studies and review articles. From each trial, information was gathered on the number and age of persons studied; the type, dosage, and duration of the intervention; and the assessed outcome measures.

RESULTS

From 1086 titles, 571 articles were excluded based on their titles. Of the remaining 467 articles, the abstracts were read and 422 articles were excluded based on information found there. The remaining articles were screened for quality aspects of the study design, leaving 21 proper randomized, controlled trials. These trials are discussed in three groups according to the type of supplementation: multinutrient intervention or single components with or without a putative mechanism. Twelve studies, which were evenly distributed among the three supplement groups, found significantly positive effects of nutritional intervention on cognitive functioning, whereas nine studies did not. None of the studies found a significantly negative effect of nutritional intervention.

CONCLUSIONS

Shortcomings in methodology varying from the duration of intervention to outcome measures partly explain discrepancies in findings. Despite the heterogeneity in trial design, the results of this review suggest that nutritional supplements may improve the cognitive functioning of elderly persons and do no harm. Further well-designed studies are needed to support these findings.

Nutritional approaches to combat oxidative stress in Alzheimer's disease

Alzheimer's disease (AD) brains are characterized by extensive oxidative stress. Additionally, large depositions of amyloid beta-peptide (Abeta) are observed, and many researchers opine that Abeta is central to the pathogenesis of AD. Our laboratory combined these two observations in a comprehensive model for neurodegeneration in AD brains centered around Abeta-induced oxidative stress. Given the oxidative stress in AD and its potentially important role in neurodegeneration, considerable research has been conducted on the use of antioxidants to slow or reverse the pathology and course of AD. One source of antioxidants is the diet. This review examines the literature of the effects of endogenous and exogenous, nutritionally-derived antioxidants in relation to AD. In particular, studies of glutathione and other SH-containing antioxidants, vitamins, and polyphenolic compounds and their use in AD and modulation of Abeta-induced oxidative stress and neurotoxicity are reviewed.

Determination of thiamine by high-performance liquid chromatography

High-performance liquid chromatographic methods for the determination of thiamine (vitamin B1) in foodstuffs or biological tissues and fluids are outlined and discussed. The methods are often similar and interchangeable, sample extraction and clean up procedures being the major difference. Most of the methods use either ultraviolet or fluorescence detection. Fluorescence detection requires either precolumn or postcolumn oxidation of thiamine to thiochrome. A number of methods are recommended and problems with standardization are emphasized.

Thiamine for Alzheimer's disease

BACKGROUND

Vitamin B1 (thiamine) plays an important role in Wernicke-Korsakoff syndrome (a form of amnesia caused by brain damage occurring in long-term alcoholics who rely mainly on alcohol for nutrition). The acute syndrome is normally reversible but may proceed to profound dementia, although its progress can be stopped by a timely injection of a large dose of thiamine. There have been suggestions that thiamine may have a beneficial effect in Alzheimer's disease.

OBJECTIVES

The objective of this systematic review is to evaluate evidence of the effect of thiamine for Alzheimer's disease.

SEARCH STRATEGY

The Cochrane Controlled Trials Register and the CDCIG Register were searched using the terms 'thiamine*, alzheimer* and vitamin* B1'. Other sources were also searched.

SELECTION CRITERIA

All unconfounded, double-blind, randomized trials in which treatment with thiamine was administered for more than a day and compared to placebo in patients with dementia of the Alzheimer's type.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two reviewers, pooled if appropriate and possible, and the pooled odds ratios (95% CI) or the average differences (95% CI) were estimated. No intention-to-treat data were available to be used.

MAIN RESULTS

Few data were available for review. The data were compatible with thiamine producing harm, no change or improvement. For measures of cognition, the effect of thiamine was non-significantly worse than placebo on the Mini Mental State Examination score (0-30; high=good) at 12 months: WMD -4.3 (95% CI: -14.4 - +5.8) and at time points 3, 6 and 9 months. Change from baseline analyses showed placebo to be significantly better than thiamine at all time points beyond three months; WMD -4.8 (95% CI: -6.0 to -3.6) at 12 months. There was no statistically significant difference in the test of Verbal Fluency and the Boston Naming Test. These analyses were based only on those who completed the study and not on intention-to-treat analyses. There were no results presented for withdrawal by treatment group. Data on measures of functional autonomy, behaviour, quality of life, dependency, or effect on carer were not available.

REVIEWER'S CONCLUSIONS

This review finds no evidence that thiamine is a useful treatment for the symptoms of Alzheimer's disease. The data are so poor and sparse that it is difficult to state almost anything of its effect in Alzheimer's disease. Thiamine cannot be recommended for patients with Alzheimer's disease.

Complementary and alternative medicines for Alzheimer's disease

The recent successes of large, multicenter clinical trials of acetylcholinesterase inhibitors for symptomatic treatment of Alzheimer's disease have spawned enthusiasm that this common and fatal neurologic disease is "treatable." A parallel explosion has occurred in the consumption of alternative medicines by the public seeking more effective, natural, or safer methods for treatment of dementia. Some of these medicines may, in fact, be biologically active in modulating the disease as well as producing side effects and interactions with accepted pharmaceuticals. This review brings to focus the scientific evidence presently available regarding such agents.

Optimum nutrition: thiamin, biotin and pantothenate

The metabolism of glucose is deranged in thiamin deficiency, but once any deficiency has been corrected there is no further effect of increased thiamin intake on the ability to metabolize glucose through either pyruvate dehydrogenase (EC 1.2.4.1) and the citric acid cycle, or the pentose phosphate pathway, in which transketolase (EC 2.2.1.1) is the thiamin-dependent step. It has been suggested that the Wernicke-Korsakoff syndrome is associated with a genetic variant of transketolase which requires a higher than normal concentration of thiamin diphosphate for activity. This finding would suggest that there may be a group of the population who have a higher than average requirement for thiamin, but the evidence is not convincing. There are no estimates of biotin requirements, but either coenzyme saturation of erythrocyte pyruvate carboxylase, or the excretion of 3-hydroxy-isovalerate (perhaps after a test dose of leucine) could be used to assess requirements in depletion-repletion studies. Biotin deficiency leads to impaired glucose tolerance, but it is unlikely that glucose tolerance could be used to assess optimum biotin status, since other more common factors affect glucose tolerance to a greater extent. Plasma triacylglycerol and nonesterified fatty acids are moderately elevated in pantothenic acid deficiency. However, this is unlikely to be useful in assessing pantothenate status, since again, other more common factors affect plasma lipids. To date there are no biochemical indices of adequate pantothenate nutrition, and no estimates of requirements.

Plasma thiamine deficiency associated with Alzheimer's disease but not Parkinson's disease

In this study we compared plasma and erythrocyte thiamine levels in a group of patients with idiopathic Parkinson's Disease (iPD) to a group of patients with probable Alzheimer's Disease (pAD). pAD patients had significantly lower plasma thiamine levels (raw and z-score) than iPD patients. A significantly higher number of pAD patients had plasma thiamine deficiencies than iPD patients. The demographics of our patient groups were similar to those reported by other investigators, making age, sex and nutritional status unlikely explanations for our findings. These results suggest that plasma thiamine deficiency is associated with pAD but not with iPD.

High-performance liquid chromatographic determination of thiamine diphosphate in erythrocytes using internal standard methodology

A high-performance liquid chromatography method for the determination of thiamine diphosphate (vitamin B1) in erythrocytes is presented. The method is robust, accurate and reproducible and due to the use of acetylaneurine as an internal standard, offers advantages over previous methods.

Beneficial effects of thiamine on recognition memory and P300 in abstinent cocaine-dependent patients

The present study evaluated the effects of thiamine vs. placebo on memory task performance and event-related electroencephalographic potentials in eight abstinent cocaine-dependent patients. Patients orally ingested 5 g of thiamine and 5 g of a lactose placebo on two separate days scheduled approximately 1 week apart. The order of administration was randomized. Double-blind procedures were followed. Approximately 3 h after ingesting the capsules, patients completed Sternberg's (1975) memory scanning task during which performance and event-related potentials (P300) were recorded simultaneously. Thiamine was found to significantly improve recognition accuracy and P300 amplitude, at the midline parietal (Pz) electrode. The improvement was most reliable under conditions of increased memory load. These preliminary findings justify a further examination of the relation between thiamine's hypothesized effects on central nervous system cholinergic function, and the direct and indirect effects of cocaine abuse.

Brain thiamine, its phosphate esters, and its metabolizing enzymes in Alzheimer's disease

Clinical data suggest that high-dose thiamine (vitamin B1) may have a mild beneficial effect in some patients with Alzheimer's disease (AD). Since this action could be related to a brain thiamine deficiency, we measured directly levels of free (nonphosphorylated) thiamine and its phosphate esters, thiamine monophosphate and thiamine diphosphate (TDP), and activities of three TDP-metabolizing enzymes (thiamine pyrophosphokinase, thiamine diphosphatase, and thiamine triphosphatase) in autopsied cerebral cortex of 18 patients with AD and 20 matched controls. In the AD group, mean levels of free thiamine and its monophosphate ester were normal, whereas levels of TDP were significantly reduced by 18 to 21% in all three cortical brain areas examined. Activities of the TDP-metabolizing enzymes were normal in the AD group, suggesting that decreased TDP is not due to altered levels of these enzymes. The TDP decrease could be explained by a cerebral cortical deficiency in AD of ATP, which is needed for TDP synthesis. Although the magnitude of the TDP reduction is slight, a chronic subclinical TDP deficiency could contribute to impaired brain function in AD and might provide the basis for the modest improvement by thiamine in cognitive status of some patients with AD.

Thiamine therapy in Alzheimer's disease

Fursultiamine (TTFD), a derivative of thiamine, at an oral dose of 100 mg/day had a mild beneficial effect in patients with Alzheimer's disease in a 12-week open trial. The improvement could be observed not only in their emotional or other mental symptoms but also in intellectual function. Only mildly impaired subjects showed cognitive improvement. Alzheimer patients' blood levels of thiamine before the trial were within the normal range. No adverse reactions were observed and all patients tolerated the trial well. TTFD could afford an alternate treatment to large doses of thiamine hydrochloride in Alzheimer patients. However, further investigations of the therapeutic implications of thiamine and its possible etiologic clues to Alzheimer's disease are necessary.

[Erythrocyte transketolases and Alzheimer disease]

Abnormalities of thiamin metabolism have been reported in senile dementia of Alzheimer's type (SDAT). Transketolases (TK) were studied in 21 patients with SDAT, 24 age-matched controls and 12 chronic alcoholics. Erythrocytes were assessed for their TK activity coefficient (TK-AC, normal value 8.4 +/- 12.6%) and affinity for thaimin pyrophosphate (Km TPP, normal value 17.8 +/- 8.3 mumol). Comparison between study groups and controls demonstrated increased TK-AC in SDAT (16.6 +/- 15.7%, P < 0.05) and chronic alcoholism (43.4 +/- 40.6%, P < 0.05), and increased Km TPP (38.3 +/- 25.2 mumol, P < 0.01) in SDAT only. These findings suggest structural abnormalities of TK rather than vitamin B1 deficiency in SDAT.