Loading clinical trials...
Loading clinical trials...
Discover 23,284 clinical trials near Maryland. Find research studies in your area.
Showing 16961-16980 of 23,284 trials
NCT01031563
Background: * Several studies of risk perception have demonstrated a common bias known as unrealistic optimism, in which individuals feel they are less likely than other people to experience unpleasant or harmful events in their lives, but more likely to experience pleasant or beneficial events. * Previous research has indicated that individuals with schizophrenia have less of a sense of unrealistic optimism about adverse events than individuals without schizophrenia. However, research on risk perception in schizophrenia is sparse, primarily reporting on behaviors and decisions in the laboratory that likely are influenced by risk perception. * Risk perception among substance users may be viewed in two separate categories: perception of vulnerability to adverse events and perception of vulnerability to negative outcomes associated with substance use. Research in both areas has yielded mixed results. Researchers are interested in studying the connections among schizophrenia, addiction, and risk perception in order to develop better drug use prevention and treatment programs for people with and without schizophrenia. Objectives: \- To compare unrealistic optimism bias in people with and without schizophrenia and/or drug dependence, and its association with actual risky behavior. Eligibility: * Individuals between 18 and 64 years of age who fall into one of the following study categories: * diagnoses of both drug dependence (marijuana or cocaine) and schizophrenia/schizoaffective disorder * diagnosis of drug dependence only (marijuana or cocaine) * diagnosis of schizophrenia/schizoaffective disorder only * healthy volunteers with no history of drug use or serious mental disorder Design: * The study will require a single visit to the research center for a 5- to 6-hour session. * Participants will complete questionnaires on medical and behavioral history, complete tests of thinking skills like memory and attention, complete a brief computerized decision-making task, and answer questions about risk perception. * Participants will also provide urine samples and breath carbon monoxide measurements to test for recent use of tobacco and other substances.
NCT00121589
This study will explore whether taking the vitamins lutein and zeaxanthin, with or without Omega-3 fatty acid (fish oil or docosahexanoic acid, also known as DHA) will change the amount of lutein and zeaxanthin in the blood among people with age-related macular degeneration (AMD). AMD is one of the leading causes of legal blindness among people over the age of 50 in developed countries. In the disease, the retina of the eye, the sensory portion, worsens in condition. AMD causes progressive loss of central vision, with only peripheral vision remaining, that is, the ability for someone to see from the edges of the eye. To date, there is not any effective treatment to improve vision for most people whose AMD is advanced. Yet some data from research studies suggest a possible role of antioxidants, including lutein, in reducing the risk of AMD and cataracts. Lutein and zeaxanthin belong to the carotenoid family of vitamins, of which there are more than 600. There are 40 or 50 carotenoids in the typical diet of human beings, but only 14 major dietary ones are identified in human plasma. Lutein, in particular, is a vitamin that is found naturally in the retina, especially in the macula, the region of the eye that is essential for fine, detailed vision. Previous studies have shown that higher levels of foods rich in Omega-3 fatty acid were associated with a lower likelihood of AMD. Patients ages 60 and older who may or may not have AMD, who do not have certain other serious eye disorders, and who have not had potentially life-threatening illness in the last year may be eligible for this study. About 40 people will participate. Patients will undergo a medical history and physical examination. A blood collection of about 4 tablespoons will be done to measure the amount of lutein and other vitamins in the blood. Patients will have a complete eye examination consisting of procedures standard to those given by ophthalmologists. Participants will have photographs taken of their eyes, and they will undergo a visual field test. Flicker photometry also will be conducted. This consists of the patients looking at a flashing bluish light with one eye at a time, and turning a knob until the light stops flashing. Then during the test, patients will look away from the light and turn the knob until the flashing stops. During this study study, patients will be asked to not take more than two tablets each day of multivitamins that contain lutein. The vitamin supplements will be provided as pills that represent one of two vitamin regimens given on a random basis: either lutein and zeaxanthin with DHA or lutein and zeaxanthin without DHA added. The amounts would be 10 mg/day of lutein and 2 mg/day of zeaxanthin, with or without 1 g/day of DHA. Patients will return to the study center for follow-up visits at 1 month, 3 months, 6 months, and 9 months. During those visits, some of the examinations done earlier will be repeated so that the researchers can evaluate the effects of supplements on patients' eyes. Patients will also be watched for possible side effects from the vitamins supplements. Lutein and zeaxanthin supplements are considered to be safe with possible minor side effects, such as headaches and difficulty in swallowing the tablets. Fish oil or DHA supplements may also cause abdominal discomfort. If information obtained from this study may be important for participants' health, they will be informed when it is available. There are no plans to give participants the results of any medical tests, evaluations, or other research data. Further research may be necessary before such results become meaningful.