Idiopathic gastric acid hypersecretion presenting as a diarrheal disorder and mimicking both Zollinger-Ellison syndrome and Crohn's disease

Many gastric acid hypersecretory states (basal acid output of greater than 15.0 mEq/h) exist for which the etiology is known, such as Zollinger-Ellison syndrome, systemic mastocytosis, antral exclusion, antral predominant Helicobacter pylori gastritis (antral G cell hyperplasia), chronic gastric outlet obstruction, short gut syndrome and basophilic leukemias. However, many hypersecretory patients have no identified etiology for their acid hypersecretion and are designated as idiopathic gastric acid hypersecretors with a basal acid output of greater than 10 mEq/h and a normal serum gastrin level. Because of the gastric acid hypersecretion these patients also commonly have an increased frequency of stools. Idiopathic gastric acid hypersecretion represents a known cause of gastric acid hypersecretion that is far more common than Zollinger-Ellison syndrome and it has a markedly different treatment regimen and natural history. We report a case of a patient with idiopathic gastric acid hypersecretion previously misdiagnosed as having Crohn's disease because of a presenting complaint of diarrhea and mimicking Zollinger-Ellison syndrome because her fasting serum gastrin level was elevated when incorrectly measured in the presence of antisecretory treatment.     

Zollinger-Ellison syndrome revisited: Diagnosis,biologic markers,associated inherited disorders,and acid hypersecretion

Despite general awareness of Zollinger-Ellison syndrome (ZES) by most physicians and more than 3000 articles written about it since 1955, the diagnosis of ZES is still delayed for a mean of 5 years. Recent studies show it is being delayed even more with the widespread use of proton pump inhibitors. A number of tumor markers, in addition to assessing serum gastrin, such as chromogranin A, neuronspecific enolase, and subunits of chorionic gonadotropin, have been proposed for use in either the diagnosis of pancreatic endocrine tumors, such as gastrinomas, or for assessment of tumor extent and growth. In this article important recent insights into the diagnosis of ZES as well as the clinical usefulness of assessing tumor markers for diagnosis and determination of disease extent and growth are discussed. Approximately 25% of ZES cases are due to multiple endocrine neoplasia type 1 (MEN1). A number of important studies in this group of patients are also reviewed. Finally, almost every patient with ZES has marked gastric acid hypersecretion, and its current treatment as well as the longterm possible side effects are reviewed briefly.     

Hyperplastic gastropathy with acid hypersecretion. A case report

The case of a 60-year-old male patient with hyperplastic hypersecretory gastropathy. The diagnosis was reached by means of the histologic study of a sample obtained by endoscopic macrobiopsy. Examination of the gastric secretions showed stimulate and basal hypersecretion; gastrinemia was normal and albumin levels were at the lower limit. Several observations are made concerning the acid secretion clinical aspects and treatment of this rare disorder.     

Diagnosis and management of Zollinger-Ellison syndrome

With the recent widespread availability of gastrin radioimmunoassays, the development of increasingly effective medical therapy for gastric hypersecretion, and improved methods to localize gastrinomas in patients with Zollinger-Ellison syndrome, the diagnosis, treatment of the gastric acid hypersecretion, and approach to the tumor have changed significantly. Recent advances in each of these areas and the current management of a patient with Zollinger-Ellison syndrome are reviewed.     

Hypersecretory duodenal ulcer and Helicobacter pylori infection: a four-year follow-up study.

BACKGROUND: About 10% of duodenal ulcer patients are characterized by gastric acid hypersecretion with normal gastrin values. Relapsing duodenal ulcer after Helicobacter pylori cure has been related to high acid output and maintenance antisecretory therapy has been suggested in hypersecretory duodenal ulcer patients. The role of Helicobacter pylori infection and the effects of Helicobacter pylori cure in hypersecretory duodenal ulcer patients still remain to be fully studied. AIM: To study: a) whether gastric acid hypersecretion "per se" is a risk factor for duodenal ulcer recurrence; b) whether maintenance antisecretory therapy is necessary after eradication in hypersecretory duodenal ulcer patients. PATIENTS: The study population comprised 8 hypersecretory duodenal ulcer patients, selected from a population of 79 Helicobacter pylori-positive duodenal ulcer patients. METHODS: Hypersecretory duodenal ulcer patients were followed-up for at least 4 years after eradication. Gastric acid secretion was measured again 12 months after Helicobacter pylori eradication. Gastroscopy with histology was performed 3, 6, 12 and 36 months after treatment, 13C-urea breath test after 42 months; clinical questionnaires were completed every 6 months. RESULTS: After eradication, despite a not significantly reduced high acid output (median value of basal acid output and pentagastrin-stimulated acid output, respectively, 23.1 mEq/h and 64.1 mEq/h before treatment vs 16 mEq/h and 49.7 mEq/h 12 months after treatment), all patients were free from symptoms, none of them had duodenal ulcer relapse or complications (7/8 before treatment), or needed antisecretory maintenance therapy, except for one patient taking non-steroidal anti-inflammatory drugs. CONCLUSIONS: These findings, obtained in a selected population of hypersecretory duodenal ulcer patients with long-term follow-up, suggest that after successful Helicobacter pylori eradication gastric acid hypersecretion "per se" is not able to determine the recurrence of duodenal ulcer.     

Hypersecretory duodenal ulcer and Helicobacter pylori infection: for-year follow-up study

Background. About 10% of duodenal ulcer patients are characterized by gastric acid hypersecretion with normal gastrin values. Relapsing duodenal ulcer after Helicobacter pylori cure has been related to high acid output and maintenance antisecretory therapy has been suggested in hypersecretory duodenal ulcer patients. The role of Helicobacter pylori infection and the effects of Helicobacter pylori cure in hypersecretory duodenal ulcer patients still remain to be fully studied.Aim. To study: a) whether gastric acid hypersecretion “per se” is a risk factor for duodenal ulcer recurrence; b) whether maintenance antisecretory therapy is necessary after eradication in hypersecretory duodenal ulcer patients.Patients. The study population comprised 8 hypersecretory duodenal ulcer patients, selected from a population of 79 Helicobacter pylori-positive duodenal ulcer patients.Methods. Hypersecretory duodenal ulcer patients were followed-up for at least 4 years after eradication. Gastric acid secretion was measured again 12 months after Helicobacter pylori eradication. Gastroscopy with histology was performed 3, 6, 12 and 36 months after treatment, ¹³C-urea breath test after 42 months; clinical questionnaires were completed every 6 months.Results. After eradication, despite a not significantly reduced high acid output (median value of basal acid output and pentagastrin-stimulated acid output, respectively, 23.1 mEg/h and 64. 1 mEg/h before treatment vs 16 mEg/h and 49.7 mEq/h 12 months after treatment), all patients were free from symptoms, none of them had duodenal ulcer relapse or complications (7/8 before treatment), or needed antisecretory maintenance therapy, except for one patient taking non-steroidal anti-inflammatory drugs.Conclusions. These findings, obtained in a selected population of hypersecretory duodenal ulcer patients with long-term follow-up, suggest that after successful Helicobacter pylori eradication gastric acid hypersecretion “per se” is not able to determine the recurrence of duodenal ulcer.     

Interdigestive Gastroduodenal Motility in Duodenal Ulcer: Role of Gastric Acid Hypersecretion

The interdigestive gastroduodenal motility was studied by means of a multilumen manometric probe in eight patients with active duodenal ulcer (group DU1) and in seven patients with hypersecretory gastroduodenitis (group GD). Both groups were selected on the basis of the presence of gastric acid hypersecretion. A group of five patients with non-active duodenal ulcer (group DU2) and a group of eight healthy subjects (group C) also were examined. Both of the latter groups were selected on the basis of the presence of normal gastric secretion. After a basal recording period of 200-300 min, in hypersecretory groups DU1 and GD, ranitidine was administered to decrease acid secretion; in normosecretory groups C and D2, impromidine was infused at two scalar doses to increase acid secretion. The basal recording showed in groups DU1 and GD a longer than normal time interval between consecutive activity fronts (AF) of the migrating motor complex (MMC cycle) and a shorter than normal percent of time occupied by AFs. In normal subjects and in DU2, the administration of the lowest dose of impromidine induced a motor pattern similar to that of the basal period of groups DU and GD, whereas the highest dose disrupted the MMC pattern that was replaced by an irregular motor activity. The results of this study indicate that duodenal ulcer with acid hypersecretion shows a marked inhibition of the MMC cycle that is not due to the ulcer itself, but to the increased acid secretion. In fact, the same motor pattern is observed in other hypersecretory states, both spontaneous and drug-induced, whereas DU with normal secretion showed a near normal motility. In active duodenal ulcer, the decreased incidence and duration of activity fronts may play a role in the pathogenesis of peptide ulcer, as it may impair the cyclic duodenal acid clearing, allowing a longer than normal contact of HCl with the duodenal mucosa.     

Overview of chronic diarrhea caused by functional neuroendocrine neoplasms.

Eight different neoplastic disorders can cause chronic diarrhea attributable to humoral-mediated diarrhea. These include pancreatic endocrine tumor (PET) syndromes (gastrinomas, VIPomas, glucagonomas, somatostatinomas, PET's releasing calcitonin), carcinoid syndrome, medullary thyroid cancer, and systemic mastocytosis. Because these disorders are an uncommon cause of all chronic diarrheas (<1%), they are not often considered in the differential diagnosis, leading to a delay in diagnosis. This is problematic not only because all are treatable, but also because the neoplasm is frequently malignant. In this article, the characteristics and pathogenesis of the diarrhea, important clinical and diagnostic laboratory features, and treatment of each disorder are briefly reviewed, with an emphasis on recent insights.     

Effects of esomeprazole on acid output in patients with Zollinger-Ellison syndrome or idiopathic gastric acid hypersecretion

OBJECTIVES: To evaluate the efficacy and safety of oral esomeprazole in the control of gastric acid hypersecretion in patients with hypersecretory states. METHODS: In this 12-month, open-label, multicenter study, acid output (AO) was evaluated at baseline, day 10, and months 3, 6, and 12. The starting dose of esomeprazole was 40 mg or 80 mg twice daily. On day 10, patients with controlled AO were maintained on the same dose, while those with uncontrolled AO had their doses increased (maximum dose 240 mg/day) until control was attained. Esophagogastroduodenoscopy (EGD) was performed at baseline and at 6 and 12 months. Safety and tolerability were assessed throughout the study by EGD, gastric analysis, and adverse events. RESULTS: Twenty-one patients (19 with Zollinger-Ellison syndrome [ZES], 2 with idiopathic gastric acid hypersecretion [IGH]) completed the study. Of the 20 patients with controlled AO at day 10, 18 (90%) had sustained AO control for the rest of the study. At 12 months, AO was controlled in 14 of 16 patients receiving esomeprazole 40 mg twice daily, in all 4 patients receiving esomeprazole 80 mg twice daily, and in the 1 patient receiving esomeprazole 80 mg 3 times daily. At 6 and 12 months, no patient had endoscopic evidence of mucosal disease. Esomeprazole was well tolerated; 1 patient had a serious adverse event (hypomagnesemia) attributed to treatment that resolved with magnesium supplementation during continued treatment. CONCLUSION: Esomeprazole in appropriately titrated doses controls AO over 12 months in patients with hypersecretory states and is well tolerated.     

Gastric secretion after massive small bowel resection

This paper confirms that gastric hypersecretion can occur in man and dogs after massive intestinal resection. The assumption, made by others, that hypersecretion in the clinical situation is similar to that observed in dogs is challenged.An acute hypersecretory state occurred in eight of 19 patients after massive intestinal resection. This was apparent as an increased rate of basal secretion. It was usually transient and unrelated to the length of intestine resected. A correlation was noticed between hypersecretion and jaundice in the immediate postoperative period. Histamine release after acute hepatic injury was postulated as the cause of the hypersecretion.By contrast a chronic gastric hypersecretory state was demonstrated in dogs after massive intestinal resection. The rate of basal secretion was not significantly altered. The increased daily acid output was shown to be due to prolonged and enhanced response to food. The cause was thought to be loss of inhibitory agents, such as enterogastrone, normally released by the small intestine when in contact with food. The rationale of performing vagotomy and pyloroplasty at the same time as the intestinal resection is questioned.     

Effect of truncal vagotomy on functional and morphological changes produced by duodenogastric reflux

The effects of truncal vagotomy on the functional and morphological changes produced by duodenogastric reflux have been studied in the dog. Duodenogastric reflux caused progressive damage to gastric mucosa, hypersecretion of acid to pentagastrin, and a hypergastrinemic response to a standard meal. Truncal vagotomy barely altered the mucosal changes produced by reflux, but it did prevent antral gland hyperplasia and reduced the acid gastrin secretory responses. These findings are clinically reassuring in that vagotomy effectively prevented the hypersecretory state produced by duodenogastric reflux.     

Idiopathic gastric acid hypersecretion

Many patients with acid-peptic disease have idiopathic gastric acid hypersecretion defined as a basal acid output >10.0 meq/hr; however, a significant proportion have basal acid outputs >15.0 meq/hr, which is within the range found in Zollinger-Ellison syndrome. Although idiopathic gastric acid hypersecretion is more common than Zollinger-Ellison syndrome, it is important that these two disorders be differentiated because of differences in treatment and natural history. In the present study, we compared 124 patients with idiopathic gastric acid hypersecretion and 137 patients with Zollinger-Ellison syndrome. There were no significant differences with regard to age at diagnosis, history of upper gastrointestinal hemorrhage, nausea, vomiting, and family history of duodenal ulcer and other acid-peptic disease. However, significant differences were observed between patients with idiopathic gastric acid hypersecretion and patients with Zollinger-Ellison syndrome with regard to percentage of males: 77% compared to 64% (P=0.008), mean serum gastrin: 60 pg/ml compared to 3679 pg/ml (normal <100 pg/ml) (P<0.001), mean basal acid output: 15.4 meq/hr compared to 47.0 meq/hr (P<0.001), mean age at onset of symptoms: 33 years compared to 41 years (P<0.001), mean duration of symptoms before diagnosis: 11 years compared to five years (P<0.001), percentage with abdominal pain: 67% compared to 82% (P=0.00004), percentage with diarrhea: 12% compared to 75% (P<0.000001), percentage with pyrosis: 58% compared to 40% (P=0.003), percentage with duodenal ulcer: 53% compared to 74% (P<0.000001), and percentage with esophagitis: 31% compared to 42% (P=0.0004). The differences in clinical features could be attributed to difference in mean basal acid output, and/or differences in levels of basal acid output used for diagnosis of idiopathic gastric acid hypersecretion (basal acid output >10.0 meq/hr) and Zollinger-Ellison syndrome (basal acid output >15.0 meq/hr). When 45 patients with idiopathic gastric acid hypersecretion and 39 patients with Zollinger-Ellison syndrome with basal acid outputs 15.1–30.0 meq/hr were compared, the main significant differences were with regard to mean serum gastrin: 69 pg/ml compared to 655 pg/ml (P<0.001), percentage of male gender: 82% compared to 62% (P=0.03), and percentage with diarrhea: 16% compared to 64% (P=0.000005). These results indicate that in general patients with idiopathic gastric acid hypersecretion and patients with Zollinger-Ellison syndrome often have similar clinical features that can be difficult to distinguish. However, the increased frequency of diarrhea and female gender should lead to a strong suspicion of Zollinger-Ellison syndrome, which can be distinguished in almost every case by measurement of serum gastrin.     

Zollinger-Ellison syndrome. Recent advances in the management of the gastrinoma

Because of increasingly effective oral antisecretory agents, gastric acid hypersecretion is now able to be controlled in all patients with Zollinger-Ellison syndrome with the result that the natural history of the gastrinoma is becoming the major determinant of long-term survival. In this article recent advances in the management of the gastrinoma itself are reviewed, including results with new modalities such as intraoperative ultrasound, MRI, and selective gastrin sampling to localize gastrinoma in patients with Zollinger-Ellison syndrome, as well as recent results of the treatment of metastatic and localized gastrinomas.     

Proton pump inhibitors in children: a review

Proton pump inhibitors are often used to treat disorders associated with gastric hypersecretion in children, despite the lack of pediatric formulations. They are highly effective in the treatment of ulcers, gastro-esophageal reflux disorders and hypersecretory diseases. They provide a high level of gastric acid inhibition with few adverse effects. The aim of this article is to review the available studies concerning the use of proton pump inhibitors in pediatric populations and to point out: indications for use in children, optimal dosage, risk of adverse effects and consequences of the mechanism of action, and drug interactions. We performed a Medline and Embase search of publications printed from January 1980 to December 2002 concerning the use of proton pump inhibitors in children. We consider the available randomised controlled trials and several other uncontrolled studies conducted in the pediatric population, including all available information concerning the pediatric use of proton pump inhibitors. In children as well as in adults, there are clinical conditions (i.e., severe esophagitis or eradication of Helicobacter pylori) in which proton pump inhibitors offer clear advantages over histamine-2 receptor antagonists. The relatively common use of acid inhibitors (proton pump inhibitors and histamine-2 receptor antagonists) in uncomplicated gastro-esophageal reflux disorders or in the prevention of non-steroidal anti-inflammatory drugs/steroid gastropathy is often unsubstantiated and should be limited to very specific situations. Multicentre randomised controlled studies are needed to better define the efficacy profile, the optimal dosage with respect to the different indications and the safety profile for chronic therapy of proton pump inhibitors in children.     

Management of the Zollinger–Ellison syndrome in patients with multiple endocrine neoplasia type 1

Jensen RT (Bethesda, MD, USA). Management of the Zollinger–Ellison syndrome in patients with multiple endocrine neoplasia type 1 (Minisymposium: MEN & VHL). J Intern Med 1998; 243 : 477–88. Zollinger–Ellison syndrome (ZES) is the most common symptomatic pancreatic endocrine tumour in patients with MEN-1. Besides the treatment of the usual endocrinopathies seen in patients with MEN-1, the treatment of the ZES requires attention be paid to controlling the gastric acid hypersecretion, to dealing with the gastrinomas per se which are malignant in 18–60% of cases, and to the diagnosis and treatment of gastric carcinoid tumours, that are increasingly seen in these patients. In this article the current management of each of the areas is reviewed and what is known or uncertain discussed, based on our studies at the NIH and data from others. Data from 231 patients including 45 with MEN-1 and 186 without MEN-1 is contrasted in this report. Gastric acid hypersecretion has been controlled in all patients medically with MEN-1 and ZES at the NIH for up to 22 years. The current drugs of choice are H⁺-K⁺ ATPase inhibitors and twice a day dosing is recommended. Periods of parenteral drug therapy (surgery, etc.) and pregnancy require important modifications. The appropriate surgical therapy of the gastrinoma is controversial. Eighty per cent of patients have a duodenal gastrinoma and 20–30% have a pancreatic tumour. Recent studies suggest gastrinoma enucleation combined with duodenotomy rarely results in cure. Aggressive surgery (Whipple resection) can result in cure of gastrinoma but effect on survival is unclear. There are important differences in gastrinoma location, extent, and percentage with aggressive disease in patients with or without MEN-1, which are discussed. Confusion has occurred because of lack of information on the natural history of the gastrinoma compared to the other pancreatic endocrine tumours that occur in MEN-1 and survival data from patients with and without MEN-1 is contrasted. The occurrence of gastric carcinoids in patients with and without MEN-1 with ZES is contrasted and the areas of certainty and disagreement reviewed.     

The role of airway secretions in COPD: pathophysiology, epidemiology and pharmacotherapeutic options

Often considered an aggravating but otherwise benign component of chronic obstructive pulmonary disease (COPD), airway mucus hypersecretion is now recognised as a potential risk factor for an accelerated loss of lung function in COPD and is a key pathophysiological feature in many patients, particularly those prone to respiratory tract infection. Consequently, it is important to develop drugs that inhibit mucus hypersecretion in these susceptible patients. Conventional therapy including anticholinergics, beta2-adrenoceoptor agonists, alone or in combination with corticosteroids, mucolytics and macrolide antibiotics are not entirely or consistently effective in inhibiting airway mucus hypersecretion in COPD. Novel pharmacotherapeutic targets are being investigated, including inhibitors of nerve activity (e.g., BK(Ca) channel activators), tachykinin receptor antagonists, epoxygenase inducers (e.g., benzafibrate), inhibitors of mucin exocytosis (e.g., anti-MARCKS peptide and Munc-18B blockers), inhibitors of mucin synthesis and goblet cell hyperplasia (e.g., EGF receptor tyrosine kinase inhibitors, p38 MAP kinase inhibitors, MEK/ERK inhibitors, hCACL2 blockers and retinoic acid receptor-alpha antagonists), inducers of goblet cell apoptosis (e.g., Bax inducers or Bcl-2 inhibitors), and purinoceptor P(2Y2) antagonists to inhibit mucin secretion or P(2Y2) agonists to hydrate secretions. However, real and theoretical differences delineate the mucus hypersecretory phenotype in COPD from that in other hypersecretory diseases of the airways. More information is required on these differences to identify therapeutic targets pertinent to COPD which, in turn, should lead to rational design of anti-hypersecretory drugs for specific treatment of airway mucus hypersecretion in COPD.     

Definition for idiopathic gastric acid hypersecretion

Zollinger-Ellison syndrome and other gastric acid hypersecretory states in which a specific etiology is identified are defined as a basal acid output of greater than 15.0 meq/hr. To determine the level of basal acid output that defines idiopathic gastric hypersecretion, basal acid outputs were investigated in normal subjects and patients with duodenal ulcers, and functional and statistical definitions for idiopathic gastric acid hypersecretion were developed. Sixty-five normal subjects were evaluated to define idiopathic gastric acid hypersecretion on a statistical basis, and 22 patients with refractory duodenal ulcers were evaluated to define idiopathic gastric acid hypersecretion on a functional basis. Mean basal acid output for the 65 normal subjects was 3.0±2.7 meq/hr. Even though the mean basal acid output for the group of 28 normal male subjects was slightly higher than for the group of 37 normal female subjects, the groups were not significantly different. The 95% confidence interval around the mean basal acid output for all normal subjects was 2.4–3.7 meq/hr, with little difference between the male and female groups. The mean basal acid output plus two standard deviations and the mean basal acid output plus three standard deviations for the 65 normal subjects were 8.4 meq/hr and 11.1 meq/hr, respectively. Of 109 patients with active duodenal ulcers treated for eight weeks with standard doses of antisecretory medication, 22 showed no healing as documented by endoscopy. The mean basal acid output for these 22 patients with nonhealed duodenal ulcers was 18.7 meq/hr (range 10.1–49.1 meq/hr) while mean basal acid output for the 87 patients with healed duodenal ulcers was 7.5 meq/hr (range 0.0–27.9 meq/hr). The difference in mean basal acid output between these two groups was statistically different (P<0.001). All patients with refractory duodenal ulcers had basal acid outputs of greater than 10.0 meq/hr. Our results indicate that the definition for idiopathic gastric acid hypersecretion should be a basal acid output of greater than 10.0 meq/hr, since, based on refractory duodenal ulcer disease, the functional definition for idiopathic gastric acid hypersecretion is a basal acid output of greater than 10.0 meq/hr, which in our data also corresponds well to the statistically defined range of basal acid output in normal subjects.     

Dyspepsia and its overlap with irritable bowel syndrome

Patients with functional dyspepsia and the irritable bowel syndrome are commonly seen in both primary care and gastroenterology subspecialty settings. Although functional dyspepsia and the irritable bowel syndrome can occur separately, recent research suggests that they often appear together as an overlap syndrome and thus may represent different portions of a unifying spectrum of disease. Despite their widespread prevalence, the pathogenesis of these disorders is not well established but may include impaired gastric emptying, gastric dysrhythmias, hypersensitivity (to acid exposure and to stretch), and Helicobacter pylori infection. Once other disorders in the differential diagnosis have been excluded, treatment of patients with functional dyspepsia, irritable bowel syndrome, and the overlap syndrome without alarm signs underscores current prevailing pathophysiologies and is generally empiric and symptom based. It is hoped that management of these disorders will become more targeted and efficacious as our understanding of them improves.     

功能性胃肠病的诊治进展

功能性胃肠病（FGIDs）是指具有腹胀、腹痛、腹泻、便秘等消化系统症状但无法以器质性病变或生化异常加以解释的一组疾病。该病极为常见,已成为当前重要公共卫生问题之一。本文结合第六届上海国际胃肠病学会议上有关专家关于功能性消化不良、慢性便秘和肠易激综合征的论述,对上述常见FGIDs的发病机制、诊断和治疗及其研究进展作一介绍。     

Other neurologic diseases with dementia as a sequela

Less-common causes of dementia are briefly discussed. Disorders covered include Pick's disease, primary progressive aphasia, progressive supranuclear palsy, Huntington's disease, olivopontocerebellar atrophies, closed head injury, dementia pugilistica, and Creutzfeldt-Jakob disease. Pseudodementia is also discussed. These disorders are compared and contrasted with the more common etiologies of dementia that are reviewed in other articles in the issue. Topics covered include treatment, differential diagnosis, clinical features, and pathogenesis.