Decline in cognitive functioning is associated with a higher mortality risk.

OBJECTIVE: This study investigates the association between 5-year change in cognitive functioning and subsequent mortality. METHODS: Four hundred and ninety-three Dutch and Italian men from the Finland, Italy, and the Netherlands Elderly (FINE) Study, born between 1900 and 1920, participated in the present study between 1990 and 2000. Cognitive functioning was measured with the Mini-Mental State Examination in 1990 and 1995, and mortality data were obtained until the year 2000. A proportional hazard analysis was used to investigate the association between 5-year change in cognitive functioning and subsequent 5-year mortality. Adjustments were made for age, education, country, lifestyle factors, prevalence of chronic diseases and, additionally, for baseline cognitive functioning. RESULTS: Men whose cognition decreased (more than 1 standard deviation) between 1990 and 1995 had a 2-fold higher risk of dying in the following 5 years compared with men whose cognition was stable (adjusted hazard ratio=1.9; 95% confidence interval 1.3-2.7). Mortality risk of men whose cognition improved between 1995 and 2000 was not different from men whose cognition was stable (adjusted hazard ratio=1.1, 95% confidence interval 0.7-1.9). CONCLUSION: A decline in cognitive functioning is associated with a higher mortality risk.

Coffee consumption is inversely associated with cognitive decline in elderly European men: the FINE Study.

OBJECTIVE: To investigate whether coffee consumption is associated with 10-year cognitive decline in elderly men, as results of previous studies obtained hitherto have been controversial and prospective information on this association has been lacking. DESIGN, SUBJECTS AND SETTING: Six hundred and seventy six healthy men born between 1900 and 1920 from Finland, Italy and the Netherlands participated in a 10-year prospective cohort study. Cognitive functioning was assessed using the Mini-Mental State Examination (0-30 points, with a higher score indicating better cognitive performance). Coffee consumption was estimated in cups per day. A mixed longitudinal model was used to investigate the association between baseline coffee consumption and 10-year cognitive decline. Multiple adjustments were made. RESULTS: Men who consumed coffee had a 10-year cognitive decline of 1.2 points (4%). Non-consumers had an additional decline of 1.4 points (P<0.001). An inverse and J-shaped association was observed between the number of cups of coffee consumed and cognitive decline, with the least cognitive decline for three cups of coffee per day (0.6 points). This decline was 4.3 times smaller than the decline of non-consumers (P<0.001). CONCLUSIONS: Findings suggest that consuming coffee reduces cognitive decline in elderly men. An inverse and J-shaped association may exist between the number of cups of coffee consumed and cognitive decline, with the least cognitive decline for men consuming three cups of coffee per day.

Intake of polyunsaturated fatty acids and vitamin E reduces the risk of developing amyotrophic lateral sclerosis.

BACKGROUND: To assess whether the premorbid dietary intake of fatty acids, cholesterol, glutamate or antioxidants was associated with the risk of developing amyotrophic lateral sclerosis (ALS). METHODS: Patients referred to our clinic during 2001-2002, who had definite, probable or possible ALS according to El Escorial criteria, without a familial history of ALS, were asked to participate in a case-control study (132 patients and 220 healthy controls). A food-frequency questionnaire was used to assess dietary intake for the nutrients of interest. Multivariate logistic regression analysis was performed with adjustment for confounding factors (sex, age, level of education, energy intake, body mass index and smoking). RESULTS: A high intake of polyunsaturated fatty acid (PUFA) and vitamin E was significantly associated with a reduced risk of developing ALS (PUFA: odds ratio (OR) = 0.4, 95% confidence interval (CI) = 0.2 to 0.7, p = 0.001; vitamin E: OR = 0.4, 95% CI = 0.2 to 0.7, p = 0.001). PUFA and vitamin E appeared to act synergistically, because in a combined analysis the trend OR for vitamin E was further reduced from 0.67 to 0.37 (p = 0.02), and that for PUFA from 0.60 to 0.26 (p = 0.005), with a significant interaction term (p = 0.03). The intake of flavonols, lycopene, vitamin C, vitamin B2, glutamate, calcium or phytoestrogens was not associated with the risk of developing ALS. CONCLUSION: A high intake of PUFAs and vitamin E is associated with a 50-60% decreased risk of developing ALS, and these nutrients appear to act synergistically.

Chest radiography and pneumonia in primary care: diagnostic yield and consequences for patient management.

The current prospective cohort study assessed the diagnostic yield of chest radiography (CXR) in primary-care patients suspected of pneumonia. In total, 192 patients with a clinical suspicion of pneumonia aged >/=18 yrs were referred by their general practitioner (GP) for CXR to one of the three participating hospitals in the Netherlands. All GPs were asked to complete a standardised form before and after CXR. Pneumonia was diagnosed by GPs in 35 (18%) patients, of whom 27 (14%) patients had a positive CXR, and eight (4%) patients a negative CXR, but with an assumed high probability of pneumonia by the GP. CXR clearly influenced the diagnosis of pneumonia by the GP in 53% of the patients. CXR ruled out pneumonia in 47% and the probability of pneumonia substantially increased in 6% of the patients. Patient management changed after CXR in 69% of the patients, mainly caused by a reduction in medication prescription (from 43 to 17%) and more frequent reassurance of the patient (from 8 to 35%). In conclusion, pneumonia was frequently over diagnosed clinically by general practitioners. Chest radiography is a valuable diagnostic tool to substantially reduce the number of patients misdiagnosed and is particularly important for the exclusion of pneumonia in general practice.

Axon loss is an important determinant of weakness in multifocal motor neuropathy.

BACKGROUND: Multifocal motor neuropathy (MMN) is characterised by asymmetrical weakness and muscle atrophy, in the arms more than the legs, without sensory loss. Despite a beneficial response to treatment with intravenous immunoglobulins (IVIg), weakness is slowly progressive. Histopathological studies in MMN revealed features of demyelination and axon loss. It is unknown to what extent demyelination and axon loss contribute to weakness. Unlike demyelination, axon loss has not been studied systematically in MMN. Aims/ METHODS: To assess the independent determinants of weakness in MMN, 20 patients with MMN on IVIg treatment were investigated. Using a standardised examination in each patient, muscle strength was determined in 10 muscles. In the innervating nerve of each muscle, axon loss was assessed by concentric needle electromyography, and conduction block or demyelinative slowing by motor nerve conduction studies. Multivariate analysis was used to assess independent determinants of weakness. RESULTS: Needle electromyography abnormalities compatible with axon loss were found in 61% of all muscles. Axon loss, and not conduction block or demyelinative slowing, was the most significant independent determinant of weakness in corresponding muscles. Furthermore, axon loss and conduction block were independently associated with each other. CONCLUSION: Axon loss occurs frequently in MMN and pathogenic mechanisms leading to axonal degeneration may play an important role in the outcome of the neurological deficit in patients with MMN. Therapeutic strategies aimed at prevention and reduction of axon loss, such as early initiation of treatment or additional (neuroprotective) agents, should be considered in the treatment of patients with MMN.

Long-term outcome in polymyositis and dermatomyositis.

BACKGROUND: Although polymyositis and dermatomyositis are regarded as treatable disorders, prognosis is not well known, as in the literature long-term outcome and prognostic factors vary widely. AIM: To analyse the prognostic outcome factors in polymyositis and adult dermatomyositis. METHODS: We determined mortality, clinical outcome (muscle strength, disability, persistent use of drugs and quality of life) and disease course and analysed prognostic outcome factors. RESULTS: Disease-related death occurred in at least 10% of the patients, mainly because of associated cancer and pulmonary complications. Re-examination of 110 patients after a median follow-up of 5 years showed that 20% remained in remission and were off drugs, whereas 80% had a polycyclic or chronic continuous course. The cumulative risk of incident connective tissue disorder in patients with myositis was significantly increased. 65% of the patients had normal strength at follow-up, 34% had no or slight disability, and 16% had normal physical sickness impact profile scores. Muscle weakness was associated with higher age (odds ratio (OR) 3.6; 95% confidence interval (CI) 1.3 to 10.3). Disability was associated with male sex (OR 3.1; 95% CI 1.2 to 7.9). 41% of the patients with a favourable clinical outcome were still using drugs. Jo-1 antibodies predicted the persistent use of drugs (OR 4.4, 95% CI 1.3 to 15.0). CONCLUSIONS: Dermatomyositis and polymyositis are serious diseases with a disease-related mortality of at least 10%. In the long term, myositis has a major effect on perceived disability and quality of life, despite the regained muscle strength.

Feasibility and cost efficiency of a diagnostic guideline for chronic polyneuropathy: a prospective implementation study.

BACKGROUND: Extensive investigations are often performed to reveal the cause of chronic polyneuropathy. It is not known whether a restrictive diagnostic guideline improves cost efficiency without loss of diagnostic reliability. METHODS: In a prospective multicentre study, a comparison was made between the workup in patients with chronic polyneuropathy before and after guideline implementation. RESULTS: Three hundred and ten patients were included: 173 before and 137 after guideline implementation. In all patients, the diagnosis would remain the same if the workup was limited to the investigations in the guideline. After guideline implementation, the time to reach a diagnosis decreased by two weeks. There was a reduction of 33% in the number and costs of routine laboratory investigations/patient, and a reduction of 27% in the total number of laboratory tests/patient, despite low guideline adherence. CONCLUSION: The implementation of a diagnostic guideline for chronic polyneuropathy can reduce diagnostic delay and the number and costs of investigations for each patient without loss of diagnostic reliability. Continuous evaluation strategies after guideline implementation may improve guideline adherence and cost efficiency.

CSF levels of angiogenesis-related proteins in patients with leptomeningeal metastases.

The authors determined the levels of vascular endothelial growth factor (VEGF) and urokinase-type plasminogen activator (uPA) in the CSF of patients with leptomeningeal metastases (LM; n = 53), cancer patients without LM (n = 18), and subjects without malignancy (n = 25). Median levels of uPA and VEGF were significantly higher in patients with LM, supporting the hypothesis that angiogenesis contributes to LM. VEGF was negatively correlated with survival in patients with LM, suggesting its use as a prognostic factor.

Multidisciplinary ALS care improves quality of life in patients with ALS.

OBJECTIVE: To examine the effect of multidisciplinary ALS care on the quality-of-life (QoL) in patients with ALS and their caregivers. METHODS: In a cross-sectional study, 208 patients with ALS and their caregivers were interviewed. QoL was assessed using the 36-item Short Form Health Survey (SF-36) and two visual analogue scales (VAS). Criteria for multidisciplinary ALS care were: an ALS team headed by a consultant in rehabilitation medicine and consisting of at least a physical therapist, occupational therapist, speech pathologist, dietician and a social worker; use of the Dutch ALS consensus guidelines for ALS care; and at least six incident ALS patients per year. RESULTS: Clinical characteristics and functional loss of the 133 patients receiving multidisciplinary ALS care and the 75 patients receiving general ALS care were similar. The percentage of patients with adequate aids and appliances was higher in those with multidisciplinary ALS care (93.1 vs 81.3%, p = 0.008), whereas the number of visits to professional caregivers was similar in both groups. Patients in the multidisciplinary ALS care group had a better mental QoL on the SF-36 Mental Summary Score than those in the general care group (p = 0.01). The difference in QoL was most pronounced in the domains of Social Functioning and Mental Health, and was independent of the presence of aids and appliances. No significant differences were found in the SF-36 Physical Summary Score, VAS, or in QoL of caregivers of patients with ALS. CONCLUSION: High standard of care improves mental quality-of-life in patients with ALS.

SMN genotypes producing less SMN protein increase susceptibility to and severity of sporadic ALS.

BACKGROUND: ALS is believed to be multifactorial in origin with modifying genes affecting its clinical expression. Childhood-onset spinal muscular atrophy (SMA) is an autosomal recessive disorder of motor neurons, caused by mutations of the survival motor neuron (SMN) gene. The SMN gene exists in two highly homologous variants: SMN1, the causative gene responsible for the production of the majority of functional SMN protein, and SMN2, responsible for the production of less protein but sufficient for modifying the SMA phenotype. OBJECTIVE: To test whether SMN genotypes are associated with susceptibility to and severity of sporadic ALS. METHODS: We performed competitive quantitative PCR analysis for both SMN1 and SMN2 genes in 242 clinically well-defined ALS patients and 175 controls. The combined determination of SMN1 and SMN2 copies also allowed for an estimation of the level of SMN for each patient (estimated SMN protein level = SMN1 copy number + 0.20 x SMN2 copy number). RESULTS: One copy of SMN1 was associated with an increased risk of developing ALS (odds ratio = 4.1, 95% CI = 1.2 to 14.2, p = 0.02) and ALS patients carried fewer SMN2 copy numbers (p < 0.001). Sixty-one percent of patients had an estimated protein SMN level < or = 2.2 vs only 36% of controls (p = 0.0000004). Multivariate Cox regression analyses showed that lower SMN2 copy numbers and lower levels of estimated SMN protein (hazard ratio = 1.3, 95% CI = 1.1 to 1.6, p = 0.03) were associated with an increased mortality rate. CONCLUSIONS: SMN genotypes producing less SMN protein increase susceptibility to and severity of ALS.

Malignant transformation in polyneuropathy associated with monoclonal gammopathy.

OBJECTIVE: To assess the frequency of hematologic malignancies at diagnosis and to determine the incidence and predictors of malignant transformation during follow-up in patients with polyneuropathy associated with monoclonal gammopathy. METHODS: Potential predictors of malignant transformation from medical history, hematologic, neurologic, and laboratory examination performed each 6 months were evaluated by univariable and multivariable Cox proportional hazard analysis. RESULTS: Of 193 patients with polyneuropathy associated with monoclonal gammopathy, 17 patients had a hematologic malignancy at diagnosis. The incidence rate of malignant transformation in 176 patients without a malignancy at diagnosis was 2.7/100 patient years. Weight loss, progression of the polyneuropathy, unexplained fever or night sweats, and M-protein level were independent predictors. CONCLUSIONS: Since hematologic malignancies occur frequently in polyneuropathy associated with monoclonal gammopathy, the authors suggest that all patients should be screened at diagnosis and subsequently during follow-up if malignant transformation is suspected.

Association between CYP1A2 activity and riluzole clearance in patients with amyotrophic lateral sclerosis.

AIMS: Riluzole is used in a fixed dosing schedule of 50 mg twice daily to treat patients with amyotropic lateral sclerosis (ALS), one form of motor neurone disease. The large variability in the pharmacokinetics of riluzole may be a factor contributing to its limited therapeutic benefit. Riluzole is assumed to be mainly metabolized by the cytochrome P450 enzyme 1A2 (CYP1A2). The aim of the study was to investigate the relationship between CYP1A2 activity and riluzole clearance with a view to optimize drug treatment. METHODS: A group of 30 ALS patients participated in the study. In each patient the CYP1A2 activity was determined using caffeine as a metabolic probe. Riluzole clearance was estimated from serum drug concentration measurements followed by Bayesian fitting. RESULTS: Riluzole clearance and the serum paraxanthine : caffeine (P/C) ratio showed a positive correlation (r = 0.693; P = 0.0002). Linear regression analysis identified the P/C ratio (beta: 1.16) and height (beta: 0.027) as independent predictors of riluzole clearance (adjusted r2 = 0.369). CONCLUSIONS: The P/C ratio, used as measure of CYP1A2 activity, significantly correlated with the riluzole clearance, although only 37% of the observed variability could be explained.

Few adverse effects of long-term creatine supplementation in a placebo-controlled trial.

Although oral creatine supplementation is very popular among athletes, no prospective placebo-controlled studies on the adverse effects of long-term supplementation have yet been conducted. We performed a double-blind, placebo-controlled trial of creatine monohydrate in patients with the neurodegenerative disease amyotrophic lateral sclerosis, because of the neuroprotective effects it was shown to have in animal experiments. The purpose of this paper is to compare the adverse effects, and to describe the effects on indirect markers of renal function of long-term creatine supplementation. 175 subjects (age = 57.7 +/- 11.1 y) were randomly assigned to receive creatine monohydrate 10 g daily or placebo during an average period of 310 days. After one month, two months and from then on every fourth month, adverse effects were scored using dichotomous questionnaires, plasma urea concentrations were measured, and urinary creatine and albumin concentrations were determined. No significant differences in the occurrence at any time of adverse effects due to creatine supplementation were found (23 % nausea in the creatine group, vs. 24 % in the placebo group, 19 % gastro-intestinal discomfort in the creatine group, vs. 18 % in the placebo group, 35 % diarrhoea in the creatine group, vs. 24 % in the placebo group). After two months of treatment, oedematous limbs were seen more often in subjects using creatine, probably due to water retention. Severe diarrhoea (n = 2) and severe nausea (n = 1) caused 3 subjects in the creatine group to stop intake of creatine, after which these adverse effects subsided. Long-term supplementation of creatine did not lead to an increase of plasma urea levels (5.69 +/- 1.47 before treatment vs. 5.26 +/- 1.44 at the end of treatment) or to a higher prevalence of micro-albuminuria (5.4 % before treatment vs. 1.8 % at the end of treatment).

Criteria for demyelination based on the maximum slowing due to axonal degeneration, determined after warming in water at 37 degrees C: diagnostic yield in chronic inflammatory demyelinating polyneuropathy.

The diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) is based on clinical and laboratory results and on features of demyelination found in nerve conduction studies. The criteria that are currently used to reveal demyelinative slowing in CIDP have several limitations. These criteria were only determined in lower arm and lower leg nerve segments, were not defined with respect to nerve temperature, and the relationship with distal compound muscle action potential (CMAP) amplitudes is unclear. The aim of our study was to determine criteria for demyelinative slowing for lower arm and leg segments as well as for upper arm and shoulder segments at a temperature of 37 degrees C, and to assess whether criteria have to be modified when the distal CMAP is decreased. Included were 73 patients with lower motor neuron disease (LMND), 45 patients with CIDP and 36 healthy controls. The arms and legs were warmed in water at 37 degrees C for at least 30 min prior to an investigation and thereafter kept warm with infrared heaters. The proposed criteria for demyelinative slowing were based on the maximum conduction slowing that may occur as a consequence of axonal degeneration and consisted of the upper boundary (99%) or the lower boundary (1%) of conduction values in LMND. In LMND, the maximum conduction slowing was different for arm and leg nerves and for segments within the arm nerves. Moreover, distal motor latency and motor conduction velocity were slower in nerves with distal CMAP amplitudes below 1 mV than in nerves with distal CMAP amplitudes above 1 mV. For these reasons, separate criteria were proposed for arm nerves, for leg nerves and for different segments within arm nerves, and more stringent criteria were proposed for distal motor latency and motor conduction velocity when the distal CMAP amplitude was below 1 mV. The diagnostic yield in CIDP was assessed using the nerve, and not the patient, as the unit of measurement. Thus, whether demyelinative slowing was present was determined for each nerve. Compared with other criteria, our criteria increased the specificity without affecting sensitivity. We conclude that the present criteria, based on the maximum slowing that may occur as a result of axonal degeneration, allow more accurate detection of demyelinative slowing in CIDP compared with other criteria. It should be emphasized that the proposed criteria can only be applied if the method of warming in water at 37 degrees C for at least 30 min is adopted.

Physical activity and the association with sporadic ALS.

OBJECTIVE: To assess whether lifetime physical activity during work and leisure time is associated with an increased risk of developing ALS and to determine the association between physical activity and duration or age at onset of disease. METHODS: Patients referred to our clinic during the 1-year period 2001 to 2002 who had definite, probable, or possible ALS according to El Escorial criteria, without a familial history of ALS, were asked to participate in the study. A case-control study was performed taking into account all occupational and leisure time activities of patients (n = 219) and controls (n = 254). Multivariate analysis included confounding factors (sex, age, level of education, body mass index, alcohol use, and smoking). Three quantitative measures of cumulative physical activity were calculated: until 1 year before the onset of disease (total physical activity), the last 10 years before the onset of disease (late physical activity), and until the age of 25 (early physical activity). In addition, a systematic review of all published data is presented. RESULTS: Smoking and alcohol use were independently associated with ALS (current smoking increased risk, OR = 1.8, 95% CI = 1.0 to 3.0, p = 0.03, ever/current alcohol use decreased risk, OR = 0.6, 95% CI = 0.3 to 0.9, p = 0.04). No significant association with occupational or leisure time physical activity was found (all ORs < or = 1.7), which was in agreement with most studies with the highest level of evidence in the systematic review. Higher leisure time activities were associated with an earlier age at onset: activity levels before age of 25 (p < 0.001, 7 years earlier), and activity during the last 10 years (p < 0.001, 3 years earlier). CONCLUSIONS: There is no association between physical activity and the risk of developing ALS.

Physical activity in relation to cognitive decline in elderly men: the FINE Study.

BACKGROUND: Physical activity may be associated with better cognition. OBJECTIVE: To investigate whether change in duration and intensity of physical activity is associated with 10-year cognitive decline in elderly men. METHODS: Data of 295 healthy survivors, born between 1900 and 1920, from the Finland, Italy, and the Netherlands Elderly (FINE) Study were used. From 1990 onward, physical activity was measured with a validated questionnaire for retired men and cognitive functioning with the Mini-Mental State Examination (maximum score 30 points). RESULTS: The rates of cognitive decline did not differ among men with a high or low duration of activity at baseline. However, a decrease in activity duration of >60 min/day over 10 years resulted in a decline of 1.7 points (p < 0.0001). This decline was 2.6 times stronger than the decline of men who maintained their activity duration (p = 0.06). Men in the lowest intensity quartile at baseline had a 1.8 (p = 0.07) to 3.5 (p = 0.004) times stronger 10-year cognitive decline than those in the other quartiles. A decrease in intensity of physical activity of at least half a standard deviation was associated with a 3.6 times stronger decline than maintaining the level of intensity (p = 0.003). CONCLUSIONS: Even in old age, participation in activities with at least a medium-low intensity may postpone cognitive decline. Moreover, a decrease in duration or intensity of physical activity results in a stronger cognitive decline than maintaining duration or intensity.

Dietary intake of fatty acids and fish in relation to cognitive performance at middle age.

OBJECTIVE: To examine the associations of fatty acid and fish intake with cognitive function. METHODS: Data are from a cross-sectional population-based study among 1,613 subjects ranging from 45 to 70 years old. From 1995 until 2000, an extensive cognitive battery was administered and compound scores were constructed for memory, psychomotor speed, cognitive flexibility (i.e., higher order information processing), and overall cognition. A self-administered food-frequency questionnaire was used to assess habitual food consumption. The risk of impaired cognitive function (lowest 10% of the compound score) according to the energy adjusted intake of fatty acids was assessed with logistic regression, adjusting for age, sex, education, smoking, alcohol consumption, and energy intake. RESULTS: Marine omega-3 polyunsaturated fatty acids (PUFA) (eicosapentaenoic acid and docosahexaenoic acid) were inversely related to the risk of impaired overall cognitive function and speed (per SD increase: OR = 0.81, 95% CI 0.66 to 1.00 and OR = 0.72, 95% CI 0.57 to 0.90). Results for fatty fish consumption were similarly inverse. Higher dietary cholesterol intake was significantly associated with an increased risk of impaired memory and flexibility (per SD increase: OR = 1.27, 95% CI 1.02 to 1.57 and OR = 1.26, 95% CI 1.01 to 1.57). Per SD increase in saturated fat intake, the risk of impaired memory, speed, and flexibility was also increased, although not significantly. CONCLUSIONS: Fatty fish and marine omega-3 PUFA consumption was associated with a reduced risk and intake of cholesterol and saturated fat with an increased risk of impaired cognitive function in this middle-aged population.

Development and implementation of the Dutch protocol for rehabilitative management in amyotrophic lateral sclerosis.

INTRODUCTION: In the Netherlands, rehabilitation care plays an important role in the symptomatic and palliative treatment of ALS patients. However, until 1999 there were no guidelines or practice parameters available for the management of ALS. Therefore, the Dutch protocol for rehabilitative management in ALS was developed. We describe the development process, the outcome and implementation of the protocol. METHODS: A concept management protocol was written and the Delphi method was selected to develop the protocol further. This method comprises repetitive discussion sessions from postulates, using a combination of written questionnaires and work-conferences. Between 80 and 90 persons (rehabilitation team members of different professional backgrounds and neurologists) were involved in this process. The protocol was implemented by sending it to all consultants in rehabilitation medicine in the Netherlands; they were asked to inform all the treatment team members about the final protocol and to implement it in their treatment of ALS patients. RESULTS: The protocol was developed in 1999, implemented in 2000 and evaluated in 2001. Recommendations for improvement were made during the evaluation and improvements are currently being developed by an expert group. The protocol is widely used (88.9%) by consultants in rehabilitation medicine and their treatment teams in the Netherlands. CONCLUSIONS: The Dutch protocol for rehabilitative management was developed to provide an optimal and adequate care plan for patients with ALS. It is widely used in the Netherlands.

Riluzole serum concentrations in patients with ALS: associations with side effects and symptoms.

Riluzole exerts a dose-dependent effect on survival of patients with ALS and, although serum levels show a high interindividual variability, is usually prescribed in a fixed dose. In this study, riluzole serum levels and area under the curve per kilogram of body weight (AUC/kg) of 169 patients with ALS showed a high interindividual variability. Patients with high serum levels and AUC/kg more often had diarrhea but less often had fasciculations and muscle stiffness. It may therefore be advantageous to raise the riluzole dose in patients with low riluzole serum concentrations without the risk of serious side effects.