Drugs with a negative impact on cognitive function (Part 1): chronic kidney disease as a risk factor

People living with chronic kidney disease (CKD) frequently suffer from mild cognitive impairment and/or other neurocognitive disorders. This review in two parts will focus on adverse drug reactions resulting in cognitive impairment as a potentially modifiable risk factor in CKD patients. Many patients with CKD have a substantial burden of comorbidities leading to polypharmacy. A recent study found that patients seen by nephrologists were the most complex to treat because of their high number of comorbidities and medications. Due to polypharmacy, these patients may experience a wide range of adverse drug reactions. Along with CKD progression, the accumulation of uremic toxins may lead to blood-brain barrier (BBB) disruption and pharmacokinetic alterations, increasing the risk of adverse reactions affecting the central nervous system (CNS). In patients on dialysis, the excretion of drugs that depend on kidney function is severely reduced such that adverse and toxic levels of a drug or its metabolites may be reached at relatively low doses, unless dosing is adjusted. This first review will discuss how CKD represents a risk factor for adverse drug reactions affecting the CNS via (i) BBB disruption associated with CKD and (ii) the impact of reduced kidney function and dialysis itself on drug pharmacokinetics.

[Reply to the Letter to the Editor "Anemia of Chronic Kidney Disease: Which Therapeutics Are Available?" Regarding the Article "Anemia in Chronic Kidney Disease: The State of the Art"]

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Cognitive disorders in patients with chronic kidney disease: Approaches to prevention and treatment

BACKGROUND

Cognitive impairment is common in patients with chronic kidney disease (CKD), and early intervention may prevent the progression of this condition.

METHODS

Here, we review interventions for the complications of CKD (anemia, secondary hyperparathyroidism, metabolic acidosis, harmful effects of dialysis, the accumulation of uremic toxins) and for prevention of vascular events, interventions that may potentially be protective against cognitive impairment. Furthermore, we discuss nonpharmacological and pharmacological methods to prevent cognitive impairment and/or minimize the latter's impact on CKD patients' daily lives.

RESULTS

A particular attention on kidney function assessment is suggested during work-up for cognitive impairment. Different approaches are promising to reduce cognitive burden in patients with CKD but the availabe dedicated data are scarce.

CONCLUSIONS

There is a need for studies assessing the effect of interventions on the cognitive function of patients with CKD.

Methodological challenges and biases in the field of cognitive function among patients with chronic kidney disease

Chronic kidney disease (CKD) affects approximately 850 million people globally and is associated with an increased risk of cognitive impairment. The prevalence of cognitive impairment among CKD patients ranges from 30 to 60%, and the link between CKD and cognitive impairment is partially understood. Methodological challenges and biases in studying cognitive function in CKD patients need to be addressed to improve diagnosis, treatment, and management of cognitive impairment in this population. Here, we review the methodological challenges and study design issues, including observational studies' limitations, internal validity, and different types of bias that can impact the validity of research findings. Understanding the unique challenges and biases associated with studying cognitive function in CKD patients can help to identify potential sources of error and improve the quality of future research, leading to more accurate diagnoses and better treatment plans for CKD patients.

[Anemia in Chronic Kidney Disease: The State of the Art]

The aging of the population has led to an increased prevalence of chronic diseases such as chronic kidney disease. Anemia is one of the most frequent complications of chronic kidney disease, with an impact not only on the quality of life but also on the patient's prognosis and associated costs. Knowledge in this therapeutic area has increased significantly: from the appearance of recombinant erythropoietin in 1989, through the use of increasing doses of parenteral iron and, more recently, to new molecules such as hypoxia-inducible factor inhibitors. The aim of this article is to present a pragmatic review of the state of the art in the epidemiology, pathophysiology, diagnosis and treatment of anemia associated with chronic kidney disease.

MO520: Prevalence of Anemia in Patients With Stage 3 or 4 Chronic Kidney Disease in Portugal–The Nefropor Study

BACKGROUND AND AIMS

Anemia is a highly prevalent and modifiable comorbidity in patients with chronic kidney disease (CKD), which tends to aggravate as the disease progresses. The economic burden of anemia in CKD is high, and quality of life issues (e.g. fatigue, reduced productivity) is common in these patients.

Data on the prevalence and treatment of anemia in CKD stages 3 and 4 (based on the estimated glomerular filtration rate according to KDIGO classification) in Portugal are lacking.

The NEFROPOR study aimed to estimate the prevalence of anemia in patients with CKD stage 3 or 4 admitted to a Nephrology consultation between 1 January and 31 March 2017 and characterize anemia treatment in this patient population.

METHODS

NEFROPOR was a retrospective, multicentric study carried out in 10 Portuguese centers. All patients aged ≥18 years with stage 3 or 4 CKD admitted to a Nephrology consultation in one of those centers between 1 January and 31 March 2017 were invited to participate, and data for up to 24 months after admission were collected from patients’ clinical files. Retrieved data included age, body mass index (BMI), anemia status according to the World Health Organization (WHO) diagnostic criteria, and anemia treatment type and duration. Three assessments of the prevalence anemia were performed: at the time of the first Nephrology visit (presentation), at the first analytical results and the overall prevalence in the study cohort. Statistical analysis was performed in SPSS Statistics (v26) and a 0.05 significance level was adopted.

RESULTS

A total of 176 patients were included in this study, mostly (61.9%) male, with a median age of 76 years (range, 26–97) and a mean BMI indicative of pre-obesity (28.2; standard deviation, 4.2). CKD stage 3b was predominant (43.2%), followed by stage 4 (32.4%) and stage 3a (24.4%). The most frequent CKD etiologies in this cohort were diabetes (39.8%), followed by arterial hypertension (27.8%) and unknown cause (25.6%). Arterial hypertension was largely the most frequent comorbidity, present in 90.3% of patients, followed by diabetes (54.0%). Although less prevalent, coronary artery disease (18.2%) and congestive heart failure (14.8%) were also identified in this patient population.

A total of 44.9% of patients [95% confidence interval (CI), 37.7%–52.3%] had anemia at presentation, which was significantly associated with CKD stage, diabetes, peripheral vascular disease and myocardial infarction comorbidities, and diabetes and unknown CKD etiology.

The overall prevalence of anemia in the study cohort was 61.9% (95% CI 54.6%–68.9%), and it was significantly associated with diabetes and peripheral vascular disease comorbidities and with diabetes and primary glomerulonephritis as CKD etiologies.

The prevalence of anemia at the first analytical results was 49.4% (95% CI 42.1%–56.8%), and it was significantly associated with CKD stage, diabetes, non-skin cancer, peripheral vascular disease and myocardial infarction comorbidities, and diabetes as CKD etiology.

Figure 1 shows the evolution of anemia treatment in this cohort over 24 + months.

CONCLUSION

The three estimates of the prevalence of anemia in this study were consistent with each other, particularly those for the first visit and first analytical results. The latter were also consistent with evidence in the literature reporting a prevalence of anemia in the population of patients with CKD stages 3 and 4 between 40% and 60%. The overall prevalence of anemia in this study was 12%–15% higher than first visit and first analytical results estimates, in agreement with the fact that this refers to a cumulative prevalence.

These data support the need for optimized and individualized treatment strategies for patients with CKD stages 3 and 4, maximizing the efficiency of health-care resource use.

P1343DOES “FISTULA FIRST” FITS TO ELDERLY?

Background and Aims

The incident patients on hemodialysis (HD) are becoming older. However, the optimal type of initial permanent vascular access (VA) among the elderly is controversial. Patient comorbidities and life expectancy are important considerations in whether to place an arteriovenous fistula (AVF) or graft (AVG).

We design an observational study to compare clinical outcomes of elderly (≥65 year old) versus younger patients, who underwent for first VA placement before initiation of renal replacement therapy, between January 2014 and December 2018.

Method

We evaluated successful use of VA, requirement of surgical interventions before successful use, VA in use after the first and third months on HD and clinical outcomes, until December 2019. The comorbidity burden was calculated through age-adjusted Charlson Comorbidity Index (aCCI).

We also evaluated the impact of comorbidity burden on the VA type on HD start and mortality after HD initiation.

Results

We identified 252 predialysis patients who underwent for VA placement in our center. We created two groups based on age at the time of VA placement: there were 199 (79,0%) with age ≥ 65 years (the elderly group), and 53 (21,0%) younger patients.

The elderly group presented a mean age of 76,3 ± 6,4 (maximum of 92) years on first VA placement; in the younger group, the mean age was 54,5 ± 9,1 (minimum of 26) years.

The following analysis are presented for elderly versus younger group. On both groups there were a predominance of male gender (66,8%; 73,6%; p=0,498) and caucasian race (95,0%; 88,7%; p=0,193).

At time of referral for AV placement, both groups presented similar mean estimated glomerular filtration rate by CKD-EPI equation (11,7 ± 3,2; 11,2 ± 3,2 mL/Kg/1,72m2; p=0,391).

Elderly group presented a significant higher aCCI (7,3 ± 1,74; 9,0 ± 1,9; p<0,001). The groups were also different in smoking status (6,0%; 30,8%; p<0,001). There were no differences on kidney disease etiology between groups, with diabetes being the most prevalent (23,1%; 24,5%; p=0,856).

For all patients, the first VA placed was AVF. Only two patient placed an AVG on second and third vascular accesses.

The median number of VA placed were similar between the two groups [1,0 (1 to 4); 1,0 (1 to 2); p= 0,811], likewise the occurrence of early complications (9,5%; 5,7%; p=0,583) and the need for surgical interventions (46,7%; 47,2%; p=1,000).

In both groups, the majority of patients started HD (80,4%; 90,6%; p=0,103), with similar successful use of the VA (68,1%; 75,0%; p=0,474).

In multivariate logistic regression, proteinuria (measured at time of referral for AV placement) and heart failure (HF) were predictors to HD initiation through a central venous catheter (CVC). This model classified correctly 74,9% of cases, with an HF odds ratio (OR) of 4,149 [confident interval (CI) of 1,721 to 10,000] and a proteinuria OR of 1,148 (CI: 1,047 to 1,259).

After the first month on HD, 34,8% of elderly patients needed a CVC, a number significantly different from the younger group (15,9%; p=0,023). The same result was observed after the third month (22,2%; 7,1%; p=0,028).

During the time of follow-up, the mortality rate was higher in the elderly group who started HD (log Rank test = 0,004), with a median survival of 29,3 (0,1 to 89,8) months, when compared to the younger group [median survival of 38,3 (0,1 to 76,9) months].

Conclusion

There were no difference in the kind of VA on HD start (definitive VA versus CVC) between the two groups. However, elderly patients presented more fistula failure in the first three months after HD initiation. The need of CVC due to nonfunctioning AVF on the first and three months after HD initiation was higher in the elderly.

The analysis of the patients who started HD showed that the elderly group presented a significant reduced survival when compared to the youngest patients.

Consecutive aquatic jump-gliding with water-reactive fuel

Robotic vehicles that are capable of autonomously transitioning between various terrains and fluids have received notable attention in the past decade due to their potential to navigate previously unexplored and/or unpredictable environments. Specifically, aerial-aquatic mobility will enable robots to operate in cluttered aquatic environments and carry out a variety of sensing tasks. One of the principal challenges in the development of such vehicles is that the transition from water to flight is a power-intensive process. At a small scale, this is made more difficult by the limitations of electromechanical actuation and the unfavorable scaling of the physics involved. This paper investigates the use of solid reactants as a combustion gas source for consecutive aquatic jump-gliding sequences. We present an untethered robot that is capable of multiple launches from the water surface and of transitioning from jetting to a glide. The power required for aquatic jump-gliding is obtained by reacting calcium carbide powder with the available environmental water to produce combustible acetylene gas, allowing the robot to rapidly reach flight speed from water. The 160-gram robot could achieve a flight distance of 26 meters using 0.2 gram of calcium carbide. Here, the combustion process, jetting phase, and glide were modeled numerically and compared with experimental results. Combustion pressure and inertial measurements were collected on board during flight, and the vehicle trajectory and speed were analyzed using external tracking data. The proposed propulsion approach offers a promising solution for future high-power density aerial-aquatic propulsion in robotics.

Molecular blueprint of allosteric binding sites in a homologue of the agonist-binding domain of the α7 nicotinic acetylcholine receptor

The α7 nicotinic acetylcholine receptor (nAChR) belongs to the family of pentameric ligand-gated ion channels and is involved in fast synaptic signaling. In this study, we take advantage of a recently identified chimera of the extracellular domain of the native α7 nicotinic acetylcholine receptor and acetylcholine binding protein, termed α7-AChBP. This chimeric receptor was used to conduct an innovative fragment-library screening in combination with X-ray crystallography to identify allosteric binding sites. One allosteric site is surface-exposed and is located near the N-terminal α-helix of the extracellular domain. Ligand binding at this site causes a conformational change of the α-helix as the fragment wedges between the α-helix and a loop homologous to the main immunogenic region of the muscle α1 subunit. A second site is located in the vestibule of the receptor, in a preexisting intrasubunit pocket opposite the agonist binding site and corresponds to a previously identified site involved in positive allosteric modulation of the bacterial homolog ELIC. A third site is located at a pocket right below the agonist binding site. Using electrophysiological recordings on the human α7 nAChR we demonstrate that the identified fragments, which bind at these sites, can modulate receptor activation. This work presents a structural framework for different allosteric binding sites in the α7 nAChR and paves the way for future development of novel allosteric modulators with therapeutic potential.

Molecular determinants of positive allosteric modulation of the human metabotropic glutamate receptor 2

BACKGROUND AND PURPOSE

The activation of the metabotropic glutamate receptor 2 (mGlu2 ) reduces glutamatergic transmission in brain regions where excess excitatory signalling is implicated in disorders such as anxiety and schizophrenia. Positive allosteric modulators (PAMs) can provide a fine-tuned potentiation of these receptors' function and are being investigated as a novel therapeutic approach. An extensive set of mutant human mGlu2 receptors were used to investigate the molecular determinants that are important for positive allosteric modulation at this receptor.

EXPERIMENTAL APPROACH

Site-directed mutagenesis, binding and functional assays were employed to identify amino acids important for the activity of nine PAMs. The data from the radioligand binding and mutagenesis studies were used with computational docking to predict a binding mode at an mGlu2 receptor model based on the recent structure of the mGlu1 receptor.

KEY RESULTS

New amino acids in TM3 (R635, L639, F643), TM5 (L732) and TM6 (W773, F776) were identified for the first time as playing an important role in the activity of mGlu2 PAMs.

CONCLUSIONS AND IMPLICATIONS

This extensive study furthers our understanding of positive allosteric modulation of the mGlu2 receptor and can contribute to improved future design of mGlu2 PAMs.

Small bait traps as accurate predictors of dipteran early colonizers in forensic studies

Insect carrion communities vary among habitats and over time. Concerning the dipteran early colonizers of carrion, the use of small bait traps should be accurate because the odors emitted from meat baits should contain many of the volatile organic compounds emitted from the freshly dead mammals. In addition, this kind of trap is easy to replicate and set in position in a given habitat. In the present study, small bait preferences of early Diptera carrion colonizers were examined in an urban biotope. Specifically, three baits were compared (pork muscle, pork liver, and fish flavored cat food) in respect to the number of specimens and species captured and the presence or absence of oviposition at high and low environmental temperatures. A total of 2371 specimens were trapped, primarily belonging to three insect orders, Diptera, Coleoptera, and Hymenoptera. Diptera was the predominant order, with blowflies (Calliphoridae) being the most representative family, followed by filth flies (Muscidae). The pork muscle bait was responsible for the highest number of captures and the highest diversity. The community of Diptera collected with the most efficient bait, pork muscle, was compared with the carrion communities reported in the literature from the Iberian Peninsula. Similar taxonomic species composition was found regarding Calliphoridae species. A specimen from all species morphologically identified were also identified at a molecular level using the cytochrome c oxidase I (COI) barcode region, and the sequences were submitted to online databases.

Synergistic action of azoreductase and laccase leads to maximal decolourization and detoxification of model dye-containing wastewaters

The azoreductase PpAzoR from Pseudomonas putida shows a broader specificity for decolourization of azo dyes than CotA-laccase from Bacillus subtilis. However, the final products of PpAzoR activity exhibited in most cases a 2 to 3-fold higher toxicity than intact dyes themselves. We show that addition of CotA-laccase to PpAzoR reaction mixtures lead to a significant drop in the final toxicity. A sequential enzymatic process was validated through the use of 18 representative azo dyes and three model wastewaters that mimic real dye-containing effluents. A heterologous Escherichia coli strain was successfully constructed co-expressing the genes coding for both PpAzoR and CotA. Whole-cell assays of recombinant strain for the treatment of model dye wastewater resulted in decolourization levels above 80% and detoxification levels up to 50%. The high attributes of this strain, make it a promising candidate for the biological treatment of industrial dye containing effluents.

Haemolytic uraemic syndrome associated with H1N1 influenza

Haemolytic uraemic syndrome (HUS) is one of the two forms of thrombotic microangiopathies and is characterized by the triad of microangiopathic haemolytic anaemia, thrombocytopaenia, and acute renal failure. It has been associated with bacterial and viral infections as well as non-infective causes. We report a subject who presented with HUS associated with an influenza-like syndrome which was confirmed as an influenza A (H1N1) infection. There are reports of HUS associated with seasonal influenza, but there have been no reported cases of HUS after novel influenza A (H1N1) in the literature so far.

Inter‐ and intralaboratory variation of in vitro diffusion cell measurements: An international multicenter study using quasi‐standardized methods and materials

In vitro measurements of skin absorption are an increasingly important aspect of regulatory studies, product support claims, and formulation screening. However, such measurements are significantly affected by skin variability. The purpose of this study was to determine inter- and intralaboratory variation in diffusion cell measurements caused by factors other than skin. This was attained through the use of an artificial (silicone rubber) rate-limiting membrane and the provision of materials including a standard penetrant, methyl paraben (MP), and a minimally prescriptive protocol to each of the 18 participating laboratories. "Standardized" calculations of MP flux were determined from the data submitted by each laboratory by applying a predefined mathematical model. This was deemed necessary to eliminate any interlaboratory variation caused by different methods of flux calculations. Average fluxes of MP calculated and reported by each laboratory (60 +/- 27 microg cm(-2) h(-1), n = 25, range 27-101) were in agreement with the standardized calculations of MP flux (60 +/- 21 microg cm(-2) h(-1), range 19-120). The coefficient of variation between laboratories was approximately 35% and was manifest as a fourfold difference between the lowest and highest average flux values and a sixfold difference between the lowest and highest individual flux values. Intralaboratory variation was lower, averaging 10% for five individuals using the same equipment within a single laboratory. Further studies should be performed to clarify the exact components responsible for nonskin-related variability in diffusion cell measurements. It is clear that further developments of in vitro methodologies for measuring skin absorption are required.

Determination of clonixin in plasma and urine by reversed-phase high-performance liquid chromatography

A reversed-phase high-performance liquid chromatographic method that enables the determination of clonixin in human plasma and urine samples is described. Recovery of the drug was over 87.6 and 80.7% for plasma and urine, respectively. The limit of quantitation of the method was established as 10 ng/ml in plasma and 20 ng/ml in urine samples, with RSDs of less than 11.1%. The applicability of the method was further assessed by determining the plasma concentrations time course of clonixin in six healthy volunteers after single oral dose administration of 150 and 300 mg of clonixin and Clonix.

Dissolution of omeprazole from delayed-release solid oral dosage forms

The evaluation of the biopharmaceutical quality of omeprazole enteric-coated products (granules in capsules) with respect to its dissolution characteristics is not specifically regulated in any of the most common official pharmacopoeia. USP 23 includes a general monograph for enteric-coated products. This paper reports the evaluation of the medium pH effect on the dissolution rates of omeprazole from four omeprazole-containing products of different manufacturers. It is concluded that the USP 23 recommended dissolution procedure for enteric-coated products is not suitable due to the degradation of omeprazole under such conditions. Furthermore, the medium with pH 8.0 showed different dissolution rates not observed at pH 7.4, allowing discrimination between products of different manufacturers.

Improved bioavailability of a micronized megestrol acetate tablet formulation in humans

Megestrol acetate, a progestogen widely used in the palliative treatment of endometrial carcinoma and breast cancer, is currently administered orally as a solid dosage form. Bioavailability of the drug following oral administration is closely related to the effectiveness and safety profile of the drug in formulation. Improved immediate-release formulations should allow improved drug delivery into the systemic circulation and, at the end, to the site of action. The micronization of drugs is one of the technological procedures to achieve such a purpose. This paper reports the design and results obtained in an in vivo study of the bioavailability of a micronized megestrol acetate tablet formulation compared to a conventional form. A significant increase in the drug bioavailability was observed, in either the rate or the extent of absorption. In vitro dissolution data of the two study formulations reflected the in vivo findings.

Topical delivery of caffeine from some commercial formulations

Permeation of caffeine through human skin and artificial membranes (mounted in modified Franz type diffusion cells) was evaluated, either from saturated solutions or from commercially available topical formulations (all containing 3% caffeine). Data interpretation of the caffeine diffusion through human skin does not implicate transfer through pores despite caffeine being a relatively polar molecule. No correlation was found between transfer though the synthetic membranes (cellulose acetate impregnated with isopropyl myristate and silicone rubber soaked in isopropyl myristate) and that observed through skin. The synthetic membranes can be used for assessing product performance in quality assurance but will give little indication of its performance in vivo. The study investigated the percutaneous permeation of caffeine through human skin in order to obtain a mechanistic interpretation of its route of permeation. Synthetic membranes were also examined to determine if they could be used as models for human skin. Different commercial formulations investigated to determine the significance of enhancement strategies.

Bioequivalence evaluation of two omeprazole enteric-coated formulations in humans

Omeprazole, a proton pump inhibitor, effectively suppresses the gastric acid secretion in the parietal cells of the stomach. Several previously published papers focus on the pharmacokinetics of the drug and its interactions with physiological aspects or with other drugs. The increasing number of omeprazole containing products available in the market, raises questions of therapeutic equivalence and/or generic substitution. The bioequivalence evaluation between two or more formulations provides information about in vivo performance. In a favorable decision regarding bioequivalence, the products are considered to have a similar therapeutic efficacy when used under the same therapeutic conditions. This paper reports the design, results and some important aspects involved in a bioequivalence study between two solid oral formulations from different manufacturers. Some important findings were the high intra-subject variability observed for Cmax and the variability observed between subject profiles, probably caused by the multi-unit type of formulations studied.

Uniformity of dosage units--comparative study of methods and specifications between Eur. Pharm. 3rd and USP 23

Methods and specifications of Eur. Ph. 3rd Ed. and USP 23 for the evaluation of the uniformity of dosage units were compared, in relation to: (i) allowed dispersion of the sample; and (ii) adequability to control the individual contents of active ingredient in relation to the labelled amount. Using the characteristics of the normal distribution curve, we calculate: (1) the highest dispersion allowable, represented by the relative standard deviation of the uniformity of mass of single-dose preparations of Eur. Ph. 3rd Ed., (results were 3.4, 5.1 and 6.8% for L1 = 5, L = 7.5 and L = 10, respectively); and (2) for all the methods studied the allowable units frequency for different intervals of the labelled amount. Differences between the tests of Eur. Ph. 3rd Ed. and USP 23 can lead to acceptance samples with very different individual contents variability, namely if the limit specifications for the strength was +/- 10%. The main reasons for that are: (1) in Eur. Ph. 3rd Ed., the limits are set with reference to the average content of the sample, and in USP 23, they are set with reference to the labelled amount of the active ingredient; and (2), the USP 23 calculates the content of active ingredient in each tablet from the result of the assay, when the weight variation method was used. Taking +/- 5% of label claim as the specification for the strength of the product, according EEC requirements, the maximum percentage of units outside the range 95-105% of label claim allowed by Eur. Ph. 3rd Ed. and USP 23 tests are similar.

Chronic headaches and sleep disorders

BACKGROUND

Headaches and sleep problems are common complaints in the daily practice of the general practitioner. Since the relationship between headaches and sleep complaints is complex, clear models of interaction are needed for adequate diagnosis and treatment.

METHODS

All subjects, successively seen in a headache clinic during a defined period, were subdivided based on the time of onset of cephalalgia. Subjects who reported onset of headache on a long-term basis, during the nocturnal or early morning (before final awakening) period, were systematically studied by a headache clinic and a sleep disorders center. This subgroup represented 17% of the total headache group.

RESULTS

Although the results of the headache clinic study did not differentiate this subgroup from the other patients, the sleep disorders center's interviews and questionnaires demonstrated a significant impact of the sleep disorders on headache and daytime function. Nocturnal monitoring during sleep identified specific sleep disorders in 55% of the subjects with onset of headache during the nocturnal sleep period. Follow-up after treatment of the sleep disorder showed that all subjects with an identifiable sleep disorder reported either an improvement or absence of their headache. The subjects identified with periodic limb movement syndrome were mostly those who reported only an improvement in their sleep and still needed treatment for their headaches. The question of the interaction and association of sleep-related headache and periodic limb movement syndrome is unresolved.

CONCLUSION

Headaches occurring during the night or early morning are often related to a sleep disturbance.