The occurrence of each event is associated with three different event times measured with the high-precision kHz programmable clock: T 0 , the last reported time before the event occurred; T 1 , the time of the event-monitoring loop associated with event occurrence; and T 2 , the time following the timing loop in which the event occurrence was first noted. While the event may have occurred before the time T 1 , Presentation may have read the time T 1 before testing for the response in the loop cycle.
As a result, the time T 2 must be used to define the upper limit of event latency. For example, consider the case where Presentation determined that no response was evident in a loop at These times establish a time range, T 2 -T 0 , which includes a time, T 0 Therefore, Presentation reports the response latency as T 0 While Presentation software minimizes interruptions due to disk access and computational operations intrinsic to the test by interleaving these operations with the high-speed event-timing loop, timing errors can still occur if the event-timing loop is interrupted by resource-demanding operations e.
For example, if a 10 ms operating system interruption occurred at the instant that the subject responded in the trial described above, the CRT latency reported would be unchanged The event-time uncertainties reported by Presentation for 10, stimulus events in Experiment 1 showed a mean of 0. The time uncertainties reported for 7, response events showed a mean of 0. In summary, these results indicate that software timing was extremely precise, and software timing errors had minimal influence on the results.
We quantified mean CRTs along with intrasubject trial-to-trial CRT standard deviations and hit rates for each type of stimulus. A response window of — ms was used: failure to generate a response during this interval was categorized as a miss, and an incorrect response occurring within the window was categorized as an error. The minimum SOA mSOA , which reflected the ability of participants to accurately respond to stimuli presented at rapid rates, was also measured for each participant.
In cases where SOAs were reduced below ms, multiple responses could occur within a response window. In these cases, responses were assigned to stimuli in the order in which they occurred. In addition, we analyzed intrasubject trial-to-trial standard deviations and the coefficient of variation CV, i. Previous large-scale studies showed a large effect of age on performance, but minimal effects of education Woods et al.
Multiple regression analysis showed that the combined influence of age and computer-use accounted for Therefore, no regressions were used when calculating log-mSOA z -scores.
Finally, omnibus z -scores were used to summarize overall performance by adding CRT z -scores and log-mSOA z -scores, and then normalizing the resulting distribution. Greenhouse—Geisser corrections of degrees of freedom were uniformly used in computing p -values in order to correct for covariation among factors and interactions. Because of the large number of statistical comparisons, significance levels were set at 0.
Mean CRT latencies from the individual participants in the first test session of Experiment 1 1A are shown as a function of age in Figure 2 green triangles , along with the results from the normative control population blue diamonds. Figure 3 shows a similar plot of mSOAs. Figure 4 shows CentPTs as a function of age, and Figure 5 shows the relationship between CRT and omnibus z -scores in the individual participants, after regressing out the effects of age and computer-use.
A summary of the different measures is provided in Table 2. Mean choice reaction times CRTs as a function of age. The age-regression slope for the normative data is shown.
Minimal stimulus onset asynchronies mSOA for subjects as a function of age. Mean central processing times CentPT as a function of age. Choice reaction time and Omnibus z -scores. Z -scores were calculated based on age- and computer-use regression slopes from the normative data. The data from four simulated malingerers with z -scores outside the range of the figure are not shown. TABLE 2. Results from Experiments 1 three sessions , 2 and 3, and normative results from a previous experiment Woods et al.
Age- and computer-use regressed CRT z -scores [ Neither CentPT z -scores [ However, there was a trend toward lower log-mSOA z -scores [ Figure 6 shows comparisons of CRT latencies across the three test sessions. ICCs across the three test sessions were used to evaluate test—retest reliability. Test—retest reliability of CRTs. Pearson correlations across repeated tests were 0. Experiment 1B , 0.
Experiment 1C and 0. Experiment 1C. This interaction reflected greater CRT latency reductions for the more difficult distractors color ms, shape ms in comparison to the distractors with no target features ms and targets ms. However, there was a significant reduction in the magnitude of the Spatial Compatibility effect on hit rate over repeated sessions [from 4. The Experiment 1 data were well-fit by the regression functions derived from the normative population: CRT z -scores, log-mSOA z -scores, CentPT z -scores, and omnibus z -scores did not differ significantly between the participants in the first test session of Experiment 1 and the normative control group.
This suggests that the regression functions relating age and computer-use in the normative population accurately corrected for the age and computer-use differences in the two populations. In his discussion on the interpretation of results of neuropsychological tests, Iverson argued that clinically useful neuropsychological tests should show ICCs that exceed 0.
The ICCs obtained in Experiment 1 equaled or exceeded those reported for both manually administered tests of processing speed and previously reported computerized CRT tests Versavel et al. As in previous reports Lemay et al. Consistent with previous reports Straume-Naesheim et al. The results contrast with the lack of learning effects in SRT paradigms Woods et al. Further analysis revealed that repeated testing resulted in larger improvements in the speed and accuracy of processing harder-to-identify stimuli.
The results also suggest that learning may influence the strength of stimulus-response spatial compatibility i. Identifying participants who perform with suboptimal effort is a significant and growing challenge in neuropsychological testing Clark et al. In particular, many patients with litigation or pension claims following head trauma show evidence of malingering on symptom-validity tests Armistead-Jehle, ; McNally and Frueh, Previous studies have shown that subjects who are instructed to malinger on CRT tests show increased CRT latencies and reduced hit rates Wogar et al.
In Experiment 2, we retested the participants of Experiment 1 after giving them instructions to malinger, with the hypothesis that they would show a similar pattern.
In addition, we were also interested in investigating the extent to which malingering participants adjusted their performance so that the magnitude of abnormality on the CRT test resembled the magnitude of abnormality observed on a previously performed SRT test Woods et al. We reasoned that CRT vs. The methods and procedures were identical to those of Experiment 1, but participants were given different instructions. After the third session of Experiment 1, participants were instructed to feign the symptoms of a patient with mild TBI during a fourth test session in the following week.
The instructions, as described previously in Woods et al. Please study the list below and develop a plan to fake some of the impairments typical of head injury when you take the test. Do your best to make your deficit look realistic. The hardware was identical to that used in Experiment 1. Event-time uncertainties for 9, stimulus presentations averaged 0. Event-time uncertainties for 6, responses averaged 0. In order to evaluate the consistency of performance on the CRT and SRT tests, we developed a latency-consistency z -score metric based on the relationship between CentPT z -scores and CRT z -scores in control participants.
Latency-consistency z -scores in Experiment 1A averaged 0. As a result, the predicted CRT latencies based on CentPT latencies in malingerers would be reduced in comparison to the CRTs actually observed, resulting in elevated latency-consistency z -scores.
Z -scores were calculated using the age- and computer-use regression slopes from the normative data. The results were analyzed using ANOVA between groups when comparing the results with those of the normative controls. Other procedures were identical to those of Experiment 1. As a result, the mean latency-consistency z -score in simulated malingerers was 8. With a more conservative latency-consistency z -score cutoff of 3.
Latency-consistency and Omnibus z -scores. A latency-consistency z -score cutoff of 3. A number of previous studies have suggested that malingering effects are often reduced as task complexity increases. For example, Kertzman et al. Wogar et al. They used a match-to-sample task in which subjects were presented with letter strings above fixation and told to choose which of the two letter strings presented below fixation matched the target string. Letter strings ranged in length from one to ten letters.
In contrast, in simulated malingerers, CRT latencies increased to 2, ms in one-letter conditions. However, the CRTs in simulated malingerers increased at the same rate as in control subjects with increasing list length. Thus, simulated malingerers showed substantial slowing in the easiest condition, but failed to adjust performance proportionally with increases in task difficulty. The results contrasted with those obtained from TBI patients, who showed increased CRT latencies in the one-letter condition and greater latency increases with increasing task complexity than either control or malingering participants.
Task-complexity effects in malingering participants may reflect the dual-task nature of malingering: malingerers must perform a primary task i. As test difficulty increases, fewer cognitive resources are available to monitor and adjust performance.
As a result, the relative magnitude of the malingering deficit decreases. The participants in Experiment 2 had undergone three prior CRT test sessions before participating in the malingering experiment. Traumatic brain injury can result in impairments in attention and processing speed Karr et al.
While processing speed usually recovers to normal levels in mTBI patients, the magnitude of processing speed deficits seen in the chronic phase of more severe TBI is one of the best predictors of ultimate functional outcome Rassovsky et al.
All patients had suffered head injuries and transient loss or alteration of consciousness, and all were tested at least 1 year post-injury. Twenty four of the patients had suffered one or more combat-related incidents with a cumulative loss of consciousness of less than 30 min, no hospitalization, and no evidence of brain lesions on clinical MRI scans.
These patients were categorized as mTBI. The remaining four patients had suffered severe accidents with hospitalization, brain abnormalities visible on neuroimaging, coma duration exceeding 8 h, and post-traumatic amnesia exceeding 72 h. These patients were categorized as sTBI.
They were informed that the studies were for research purposes only and that the results would not be included in their official medical records. Two mTBI patients showed evidence of suboptimal effort, with latency-consistency z -scores of These same two patients had shown evidence of suboptimal effort in other experiments performed during the same test session Hubel et al.
Their data were therefore excluded from further analysis. People with allergies should avoid or minimize exposure to certain other irritants that can make allergic symptoms worse or cause breathing problems. These irritants include the following:. Allergen immunotherapy, usually allergy shots injections , can be given to desensitize people to the allergen when some allergens, especially airborne allergens, cannot be avoided and the drugs used to treat allergic reactions are ineffective.
However, allergen immunotherapy is not always effective. Some people and some allergies tend to respond better than others. When people are allergic to unavoidable allergens, such as insect venom, immunotherapy helps prevent anaphylactic reactions Anaphylactic Reactions Anaphylactic reactions are sudden, widespread, potentially severe and life-threatening allergic reactions.
Sometimes it is used for allergies to animal dander, but such treatment is unlikely to be useful. Immunotherapy for peanut allergy is available, and immunotherapy for other food allergies is being studied.
Immunotherapy is not used when the allergen, such as penicillin and other drugs, can be avoided. However, if people need to take a drug that they are allergic to, immunotherapy, closely monitored by a doctor, can be done to desensitize them. In immunotherapy, tiny amounts of the allergen are usually injected under the skin. The dose is gradually increased until a dose adequate to control symptoms maintenance dose is reached.
A gradual increase is necessary because exposure to a high dose of the allergen too soon can cause an allergic reaction. Injections are usually given once or twice a week until the maintenance dose is reached.
Then injections are usually given every 2 to 4 weeks. The procedure is most effective when maintenance injections are continued throughout the year, even for seasonal allergies. Alternatively, high doses of the allergen may be placed under the tongue sublingual and held there for a few minutes, then swallowed.
The dose is gradually increased, as for injections. The sublingual technique is relatively new, and how often the dose should be given has not been established. It ranges from every day to 3 times a week.
Extracts for grass pollen or house dust mite, placed under the tongue, can be used to help prevent allergic rhinitis. Immunotherapy for peanut allergy may also be given by mouth. The person receives the first several doses of the allergen over the course of a single day while in a doctor's office or clinic. The person then takes the allergen at home. Each time the dose is increased, the first dose of the higher dosage is given under a doctor's supervision.
Allergen immunotherapy may take 3 years to complete. People who develop allergies again may need another longer course sometimes 5 years or more of immunotherapy.
If they have mild reactions to immunotherapy such as sneezing, coughing, flushing, tingling sensations, itching, chest tightness, wheezing, and hives , a drug—usually an antihistamine, such as diphenhydramine or loratadine —may help. For more severe reactions, epinephrine adrenaline is injected. Avoiding the allergen Environmental measures Allergic reactions hypersensitivity reactions are inappropriate responses of the immune system to a normally harmless substance.
Usually, allergies make people sneeze; the eyes water and itch If mild symptoms occur, antihistamines are often all that is needed. If they are ineffective, other drugs, such as mast cell stabilizers and corticosteroids may help. Nonsteroidal anti-inflammatory drugs NSAIDs are not useful, except in eye drops used to treat conjunctivitis. Severe symptoms, such as those involving the airways including anaphylactic reactions , require emergency treatment.
The drugs most commonly used to relieve the symptoms of allergies are antihistamines. Antihistamines block the effects of histamine which triggers symptoms. They do not stop the body from producing histamine. Taking antihistamines partially relieves the runny nose, watery eyes, and itching and reduces the swelling due to hives or mild angioedema. But antihistamines do not ease breathing when airways are constricted. Some antihistamines such as azelastine are also mast cell stabilizers Mast cell stabilizers Allergic reactions hypersensitivity reactions are inappropriate responses of the immune system to a normally harmless substance.
Which is used depends on the type of allergic reaction. Some antihistamines are available without a prescription over-the-counter, or OTC , and some require a prescription.
Some that used to require a prescription are now available OTC. Products that contain an antihistamine and a decongestant such as pseudoephedrine are also available OTC. They can be taken by adults and children aged 12 years and older. These products are particularly useful when both an antihistamine and a nasal decongestant are needed.
However, some people, such as those who are taking monoamine oxidase inhibitors a type of antidepressant , cannot take these products. Also, people with high blood pressure should not take a decongestant unless a doctor recommends it and monitors its use.
The antihistamine diphenhydramine is available OTC as a lotion, cream, gel, or spray that can be applied to the skin to relieve itching, but it should not be used. Its effectiveness is unproved, and it can cause allergic reactions such as a rash. It can cause extreme drowsiness in children who are also taking an antihistamine by mouth. Over-the-counter skin products that contain diphenhydramine an antihistamine should not be used because their effectiveness is unproved and because allergic reactions and other side effects are possible.
Side effects of antihistamines include anticholinergic effects, such as drowsiness, dry mouth, blurred vision, constipation, difficulty with urination, confusion, and light-headedness particularly after a person stands up , as well as drowsiness. Often, prescription antihistamines have fewer of these effects. Some antihistamines are more likely to cause drowsiness sedation than others. Antihistamines that cause drowsiness are widely available OTC.
People should not take these antihistamines if they are going to drive, operate heavy equipment, or do other activities that require alertness. Antihistamines that cause drowsiness should not be given to children under 2 years old because they may have serious or life-threatening side effects.
Drugs, the most common medical intervention, are an important part of medical care for older people. Without drugs, many older people would function less well or die at an earlier age. In general, doctors use antihistamines cautiously in people with cardiovascular disease. Not everyone reacts the same way to antihistamines.
For example, Asians seem to be less susceptible to the sedative effects of diphenhydramine than are people of Western European origin. Also, antihistamines cause the opposite paradoxical reaction in some people, making them feel nervous, restless, and agitated. Mast cell stabilizers block mast cells from releasing histamines and other substances that cause swelling and inflammation. Mast cell stabilizers are taken when antihistamines and other drugs are not effective or have bothersome side effects.
These drugs may help control allergic symptoms. These drugs include azelastine , cromolyn , lodoxamide , ketotifen , nedocromil , olopatadine , and pemirolast. Azelastine , ketotifen , olopatadine , and pemirolast are also antihistamines. Cromolyn is available without a prescription as a nasal spray to treat allergic rhinitis. Cromolyn usually affects only the areas where it is applied, such as the back of the throat, lungs, eyes, or nose.
When taken by mouth, cromolyn can relieve the digestive symptoms of mastocytosis Mastocytosis Mastocytosis is an uncommon abnormal accumulation of mast cells in the skin and sometimes in various other parts of the body. People may have itchy spots and bumps, flushing, digestive upset When antihistamines and mast cell stabilizers cannot control allergic symptoms, a corticosteroid may help.
Corticosteroids can be taken as a nasal spray to treat nasal symptoms or through an inhaler, usually to treat asthma. Doctors prescribe a corticosteroid such as prednisone to be taken by mouth only when symptoms are very severe or widespread and all other treatments are ineffective. If taken by mouth at high doses and for a long time for example, for more than 3 to 4 weeks , corticosteroids Corticosteroids: Uses and Side Effects Rheumatoid arthritis is an inflammatory arthritis in which joints, usually including those of the hands and feet, are inflamed, resulting in swelling, pain, and often destruction of joints Therefore, corticosteroids taken by mouth are used for as short a time as possible.
Creams and ointments that contain corticosteroids can help relieve the itching associated with allergic rashes. However, this is easier said than done as many jewelry products contain metals like nickel. Silver or gold plated jewelry contain nickel alloys underneath. Any gold jewelry that is less than 24K, such as white gold, will also contain a mixture of metals to provide structure to soft, pure gold. Here are some ways you can continue to wear inexpensive jewelry and keep your skin safe at the same time:.
Look for hypoallergenic jewelry such as nickel-free stainless steel, surgical-grade stainless steel, titanium, platinum, sterling silver, and 18K gold. Avoid buying jewelry plated with another metal or made of mixed metals like white gold. Creating barriers will help you reduce the risk of an allergic reaction while handling metals.
With jewelry, three coats of clear nail polish can do the trick. Apply the clear nail polish on the part of the jewelry that comes into contact with your skin, so you limit the amount of irritants that interact with body heat and sweat.
Be sure to reapply additional coats of polish after a few wears. Check if the studio uses sterile, sealed surgical-grade stainless steel needles. Ask your piercer for hypoallergenic jewelry made of sterling silver or similar metals, and see if they can provide documentation on the metal content of their products.
Let our team of dermatologists help you figure out what type of jewelry you can safely wear, and treat any skin issues you might be experiencing. Schedule an appointment now. Walk-in Dermatology Management, LLC shall, in no way, determine or set the methods, standards, or conduct of the practice of medicine or healthcare provided at, by, or through any medical center, or by any of its professionals. Patient Delight! Book Appointment. Video Visits Now Available. Office Information.