Table 1.
Group comparison for demographic characteristics.
Table 2.
Group comparison for psychometric characteristics and Correlation with noise.
Fig 1.
Relationship of PERG background noise to stimulus contrast.
Controls are displayed in blue, patients with ADHD in red. The thick, nearly horizontal lines represent a first-order model fit to the pertinent data points, the gray-shaded areas indicate its ±SEM interval. The distribution of the original data points can be gleaned from the box plots, where the median is indicated by short thick horizontal lines, the box covers the 25–75% percentile range, the whiskers indicate the range, outliers are indicated with dots. The background noise is markedly higher (138%) in patients with ADHD (red) compared to the controls (blue, p<0.005) and does not depend on stimulus contrast (lines are almost horizontal). This differs from the PERG stimulus response, which we added for comparison as dashed lines (data from [26]); the PERG response amplitude rises linearly with stimulus contrast.
Table 3.
Amplitude of neuronal noise and number of artefacts.
Fig 2.
Group comparison of mean neuronal noise.
Boxplot showing the comparison of background noise in μV (y axis) between healthy control subjects (HC) and patients with ADHD; noise was averaged across all contrast levels per subject. Patients presented with a significant elevated background noise (p<0.005). Left: control group; right: patients with ADHD. Small disks or triangles, respectively, represent the individual data points. Boxplot details as in Fig. 1, the notches represent a 95% confidence interval for the medians.
Fig 3.
Correlation between background noise and DSM-IV inattentive symptoms, measured with the CAARS-S-L.
Healthy controls are represented by blue disks, patients with ADHD by red triangles. Higher ADHD symptoms of inattention are associated with higher background noise (r = 0.44; p = 0.004). The correlation is represented by the line, while the gray-shaded area indicates its ±SEM interval.