Objectives

ADHD patients often report that they are being flooded by sensory impressions. Studies investigating sensory processing show hypersensitivity for sensory inputs across the senses for children and adults with ADHD. For our daily interaction with the environment a complex interplay of the senses is necessary to form a unified percept. In order to achieve this, the unimodal sensory modalities are bound together in a process called multisensory integration (MI).

In the current study we investigate MI in an adult ADHD sample accompanied by resting-state functional magnetic resonance imaging (RS-fMRI).

Methods

Twenty-five ADHD patients and twenty-four healthy controls were recruited. MI was examined with the McGurk effect, where - in case of successful MI - incongruent speech-like phonemes between visual and auditory modality are leading to a perception of a new phoneme. Mann-Whitney-U test was applied to assess statistical differences between groups. Resting-state functional MRI (3T) was acquired and seed-to-voxel analysis was realized using the CONN toolbox.

Results

Susceptibility to MCGurk was significantly lowered for ADHD patients (ADHD_Mdn:5.83%, Controls_Mdn:44.2%, U= 160.5, p=0.022, r=-0.34). When ADHD patients integrated phonemes, reaction times were significantly longer (ADHD_Mdn:1260ms, Controls_Mdn:582ms, U=41.0, p<.000, r= -0.56). Seeded medio temporal gyrus was negatively associated in functional connectivity to primary auditory cortex, inferior frontal gyrus, precentral gyrus, and fusiform gyrus.

Conclusions

MI seems to be deficient for ADHD patients for stimuli that need top-down attentional allocation. This finding is supported for higher functional connectivity from unimodal sensory areas to polymodal, MI convergence zones for complex stimuli. This may have consequences for social interaction.