The Dallas Asthma Brain and Cognition (ABC) Study

Primary outcomes

1. Examine processing speed of middle- to late-age adults with asthma with the Wechsler Adult Intelligence Scale (WAIS) Symbol Search Test.

   Time frame: From date of baseline until the date of second session, approximately one week after baseline.

   The Wechsler Adult Intelligence Scale (WAIS) Symbol Search test is a subtest of the WAIS, a scale widely used to measure intelligence. The examinee scans a search group of symbols and indicates whether one of the symbols matches a symbol in the target group. The time limit for this subtest is 120 seconds. The total raw score is the sum of the number of correct responses minus the number of incorrect responses. A higher score indicates better performance. The maximum total raw score is 60. If the total raw score is equal to or less than 0, then the total raw score is recorded as 0.

2. Examine executive functioning of middle- to late-age adults with asthma with the Trails A&B test.

   Time frame: From date of baseline until the date of second session, approximately one week after baseline.

   The Trails A&B test is a neuropsychological assessment. The task requires a subject to connect a sequence of 25 circles on a sheet of paper as quickly as possible. The test has 2 parts, with the first part of the test requiring the subject to connect circles that are all numbers (1, 2, 3, etc.) in order. The second part of the test requires that the subject alternates between numbers and letters (1, A, 2, B, etc.). The time taken for each part, measured in seconds, is the raw score. The score is then converted to a scaled score and a T score, both based on sex (male, female), race, and age. A higher score indicates better performance.

3. Examine working memory of middle- to late-age adults with asthma with the National Institute of Health (NIH) Sorting Working Memory Test.

   Time frame: From date of baseline until the date of second session, approximately one week after baseline.

   The National Institute of Health Sorting Working Memory Test is a computerized test that requires the subject to sequence sets of visually and auditorily presented stimuli (pictures of animals and food) in size order from smallest to biggest. There are two lists, with the 1-list version requiring sequencing among a single category (either animals or food), and the 2-list version (requiring sequencing of both food and animals within a series). The raw score is based on the sum of the correct across both lists, which comprise the List Sorting "Total Score". The raw score is converted into a t-score (mean = 50, standard deviation = 10). A higher score indicates better performance.

4. Examine episodic memory of middle- to late-age adults with asthma with the Rey Auditory Verbal Learning Test (RAVLT).

   Time frame: From date of baseline until the date of second session, approximately one week after baseline.

   The examiner reads a list of 15 nouns aloud at the rate of one per second. The subject is asked to repeat all words they recall over 5 trials. An interference list (List B) is then read and subject is asked to recall. Immediately following the interference trial, the subject is asked to recall words from List A (Trial 6). After a 20 minute delay the subject is asked to recall as many words as possible from the first list (delayed recall). A list of 50 words is presented containing all words from List A and the subject is asked to indicate whether each word was on List A (recognition task). The total score (Trials 1-5) is calculated by summing the correct number of words for each trial. List B, Trial 6 and Delayed Recall are calculated by summing the correct number of words. Recognition task is scored by taking the number of correct words and subtracting the number of false positive words. Scores are converted into t-scores with higher score indicating better performance.

5. Examine reasoning of middle- to late-age adults with asthma with the National Adult Reading Test (NART).

   Time frame: From date of baseline until the date of second session, approximately one week after baseline.

   The National Adult Reading Test is a commonly used test to measure intellectual ability in English-speaking patients. A list of 50 words, whose pronunciation cannot be determined from their spelling, are given to the subject and the subject is asked to read down the list. The examiner marks whether the subject pronounced the word correctly and the NART is scored by summing the number of words pronounced correctly.

6. Examine brain function of adult asthma patients from age 40-69 with functional magnetic resonance imaging (fMRI)

   Time frame: From date of baseline until the date of second session, approximately one week after baseline.

   We will assess brain functioning by measuring default brain network connectivity using functional magnetic resonance imaging (fMRI)

7. Examine brain structure of adult asthma patients from age 40-69 with structural magnetic resonance imaging (sMRI)

   Time frame: From date of baseline until the date of second session, approximately one week after baseline.

   We will assess brain structure, hippocampal gray matter volume, using structural magnetic resonance imaging (sMRI)

8. Examine brain chemistry of adult asthma patients from age 40-69 with proton magnetic resonance spectroscopy (1H-MRS)

   Time frame: From date of baseline until the date of second session, approximately one week after baseline.

   We will assess brain chemistry, specifically differences in hippocampal metabolite levels, using proton magnetic resonance spectroscopy (1H-MRS)