Background: Cacace and McFarland (2005) have suggested that the addition of cross-modal analogs
will improve the diagnostic specificity of (C)APD (central auditory processing disorder)
by ensuring that deficits observed are due to the auditory nature of the stimulus
and not to supra-modal or other confounds. Others (e.g., Musiek et al, 2005) have
expressed concern about the use of such analogs in diagnosing (C)APD given the uncertainty
as to the degree to which cross-modal measures truly are analogous and emphasize the
nonmodularity of the CANs (central auditory nervous system) and its function, which
precludes modality specificity of (C)APD. To date, no studies have examined the clinical
utility of cross-modal (e.g., visual) analogs of central auditory tests in the differential
diagnosis of (C)APD.
Purpose: This study investigated performance of children diagnosed with (C)APD, children diagnosed
with ADHD (attention deficit hyperactivity disorder), and typically developing children
on three diagnostic tests of central auditory function and their corresponding visual
analogs. The study sought to determine whether deficits observed in the (C)APD group
were restricted to the auditory modality and the degree to which the addition of visual
analogs aids in the ability to differentiate among groups.
Research Design: An experimental repeated measures design was employed.
Study Sample: Participants consisted of three groups of right-handed children (normal control,
n = 10; ADHD, n = 10; (C)APD, n = 7) with normal and symmetrical hearing sensitivity,
normal or corrected-to-normal visual acuity, and no family or personal history of
disorders unrelated to their primary diagnosis. Participants in Groups 2 and 3 met
current diagnostic criteria for ADHD and (C)APD.
Data Collection and Analysis: Visual analogs of three tests in common clinical use for the diagnosis of (C)APD
were used (Dichotic Digits [Musiek, 1983]; Frequency Patterns [Pinheiro and Ptacek,
1971]; and Duration Patterns [Pinheiro and Musiek, 1985]). Participants underwent
two 1 hr test sessions separated by at least 1 wk. Order of sessions (auditory, visual)
and tests within each session were counterbalanced across participants. ANCOVAs (analyses
of covariance) were used to examine effects of group, modality, and laterality (Dichotic/Dichoptic
Digits) or response condition (auditory and visual patterning). In addition, planned
univariate ANCOVAs were used to examine effects of group on intratest comparison measures
(REA, HLD [Humming-Labeling Differential]).
Results: Children with both ADHD and (C)APD performed more poorly overall than typically developing
children on all tasks, with the (C)APD group exhibiting the poorest performance on
the auditory and visual patterns tests but the ADHD and (C)APD group performing similarly
on the Dichotic/Dichoptic Digits task. However, each of the auditory and visual intratest
comparison measures, when taken individually, was able to distinguish the (C)APD group
from both the normal control and ADHD groups, whose performance did not differ from
one another.
Conclusions: Results underscore the importance of intratest comparison measures in the interpretation
of central auditory tests (American Speech-Language-Hearing Association [ASHA], 2005;
American Academy of Audiology [AAA], 2010). Results also support the “non-modular”
view of (C)APD in which cross-modal deficits would be predicted based on shared neuroanatomical
substrates. Finally, this study demonstrates that auditory tests alone are sufficient
to distinguish (C)APD from supra-modal disorders, with cross-modal analogs adding
little if anything to the differential diagnostic process.
Key Words Attention deficit hyperactivity disorder - central auditory processing - dichoptic
- dichotic - modality specificity - temporal patterning
