Week Twelve:
ADHD and Development Lab

Carhart Fellow in Clinical Psychology

ADHD and Development Lab, University of Iowa | Iowa City, Iowa

August 21, 2015

This week marked the final week of my fellowship at the Iowa ADHD and Development Lab. I spent my final week conducting preliminary statistical analysis and wrapping up data entry for our lab visits. Unfortunately, I wasn’t able to complete the first round of data entry on all the archival data files, though I did manage to complete data entry for the lab visits that our lab had done this summer. It was a personal goal of mine to complete that phase of the project, but you can only do so much, I suppose!

Running some univariate and multivariate analyses on a subset of our data to identify possible group differences, I noticed a few trends, many of which are consistent with what could be predicted based on the present literature. I also ran a few regression analyses, as well, because I am personally most familiar with those sorts of statistical analyses. It is also important to note that what I will be reporting on should not be taken as representative of the true population of adults with or without ADHD or depression, nor should it be considered truly representative of our total sample, which is going to be expanded upon in the coming months. This is only a portion of our data pool from what we have presently. Moreover, there are likely small differences between our sample and other samples of adults. What I am reporting on should be interpreted in light of these limitations, and considered questionable, at best.

Figure 1. The normal distribution of full-scale IQ with percentile rank (average = 100 IQ).
Figure 1. The normal distribution of full-scale IQ with percentile rank (average = 100 IQ).

To recap from my present blog post, the current data set includes 58 adults with ADHD, 8 adults with depression, and 8 adults with no history of psychiatric or psychological disorder, serving as our control group. Having run descriptive analyses, the average age in the total sample (i.e. across groups) is 25 years of age (SD = 6.1, range 18-39), which indicates our sample has a lesser representation of adults aged 30 or more years. Females are slightly over-represented in the present sample (55.9%). Our sample is chalk full of rather intelligent individuals as indicated by the mean estimate full scale IQ (EFSIQ) at 116 (SD = 13.7), which is a full standard deviation above normal or average intelligence (Figure 1). Fortunately, our present sample does not vary significantly based on age, sex, gender, ethnicity, education, or EFSIQ. So, we seem to be good to go in terms of moving forward.

From what I was able to find, adults with ADHD in the present sample appeared to perform significantly worse on certain tasks measuring nonverbal working memory (Salthouse Listening Span, Sentence Repetition, Spatial Addition), verbal working memory (CVLT), executive functioning (D-KEFS), and sustained attention (TOVA, PASAT). On measures of nonverbal working memory, EFSIQ played a significant role in differentiating performance across groups (which is not that surprising as working memory is positively correlated with intelligence). In regard to verbal working memory, adults with ADHD perform worse on tasks requiring them to recall words without retrieval cues. In addition, adults with ADHD appear to utilize learning strategies less efficiently. Coinciding with these findings, indices of verbal learning strategies on the CVLT were negatively correlated with self-report behavioral rating scales of executive dysfunction, suggesting more problems related to executive functioning begets poorer performance on verbal learning tasks. On executive functioning tasks, adults with ADHD performed worse on tasks involving competing rules (e.g. report the color word when it is inside a box and report the ink color when the color word isn’t inside a box or draw different designs using only four straight lines switching from an empty dot to a filled dot after each successive line drawn) and planning. On the PASAT, adults with ADHD did significantly worse than controls. Adults with ADHD frequently became overwhelmed on this task, as it is particularly taxing on working memory and attentional control.

As this will be my final blog post, I would like to acknowledge those who made my fellowship possible. I’d like to thank my site mentor, Dr. Molly Nikolas, for a wonderful and engaging internship within her lab. I have truly learned from her mentorship. I would also like to thank those who I worked with on a more regular basis, and I wish them the best in their endeavors – many of them are going onto graduate school, if they have not already been working toward their graduate degrees. Finally, I would like to thank the donors to my fellowship for their generosity. Through this internship, I have come to further develop my interests, skills, and career goals. Though I am still processing my experience in the lab, it has surely aided in refining these “next steps” toward graduate school in clinical psychology. Thank you!

Molly, Jackie, Allison, and I in the lab workroom.
Molly, Jackie, Allison, and I in the lab workroom.
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Andrew Crow '16

Andrew is a Psychology and Philosophy major from Milwaukee, Wisconsin.