Neuropsychological tests and functional impairment in adult attention deficit hyperactivity disorder : with special reference to memory disturbance

Aim: To investigate the possible use of different neuropsychological tests for diagnosis of adult patients with Attention Deficit Hyperactivity Disorder (ADHD), with specific reference to memory tests.

Methods: Patients were referred from psychiatric out-patient units as part of routine clinical assessment. 158 adults were diagnosed with DSM-IV-TR, median age 32 years. A clinical interview was conducted together with four self-report questionnaires. The patients were neuropsychologically assessed before possible treatment, and were followed-up three years later. A group of 13 standard neuropsychological tests and a dichotic memory test were administered. At telephone follow-up three years later, the patients were interviewed with ASRS v1.1 to assess their ADHD symptoms, and some new questions were posed about functional impairment.

Results: A significant reduction was found in memory tests, including dichotic memory, in the study group after analysis for the covariance (ANCOVA) effects of IQ, sex, age, and years of education; the effects of depression and anxiety on the HAD scale had been removed. Profound reduction was found on the working memory capacity tests with distracters: the Consonant Trigram test, the Dichotic Memory test and the Benton VRT. Reductions were also found in learning and delayed recall on the Rey Auditory Verbal Learning test and the modified Diagnosticum für Cerebralschädigung. Minor but significant reductions were found on Digit Span Backward (WAIS), Arithmetic Capacity (WAIS), Raven SET I, WCST Number of Perseverations and in the Trail Making B test, compared with controls. At follow-up, an ADHD medicated group showed a significant reduction in their symptoms compared with non-medicated patients, and also better self-confidence. The rate of employment was low; in total, 58 % were without employment, even after medication.

Conclusions: In adult patients with ADHD, neuropsychological testing using working memory capacity tests with distracters, demonstrate a reduced working memory capacity. In a follow-up, patients on medication showed fewer symptoms and better self-confidence, but many continued to be unemployed.

List of scientific papers

I. Dige N, Wik G (2005). "Adult attention deficit hyperactivity disorder identified by neuropsychological testing." Int J Neurosci 115(2): 169-83
https://pubmed.ncbi.nlm.nih.gov/15763999

II. Dige N, Maahr E, Backenroth-Ohsako G (2008). "Memory tests in subgroups of adult attention deficit hyperactivity disorder reveals simultaneous capacity deficit." Int J Neurosci 118(4): 569-91
https://pubmed.ncbi.nlm.nih.gov/18322864

III. Dige N, Maahr E, Backenroth-Ohsako G (2009). "Reduced capacity in a dichotic memory test for adult patients with ADHD." J Atten Disord Sep 25: Epub ahead of print
https://pubmed.ncbi.nlm.nih.gov/19783809

IV. Dige N, Hetta J, Backenroth-Ohsako G (2009). "A naturalistic 3-year telephone follow-up study of outcomes in adults diagnosed with Attention Deficit Hyperactivity Disorder." Nordic Journal of Psychiatry (Submitted)