Experimental design and tasks.

<p>(A) tDCS conditions and tasks were independently randomly ordered across participants. Encoding and recognition, as well as tDCS conditions were separated by ∼72 hours to test long-term recognition and avoid cross-over cortical excitability modulation effects. (B) Example of one encoding task block. Encoding tasks consisted of three blocks, each comprising 15 different unfamiliar faces presented 15 times consecutively. (C) Example of a corresponding recognition task. The 45 unfamiliar faces encoded ∼72 hours earlier are presented amongst 45 novel faces. For each face, participants responded either "known" or "unknown" (here, correct answers are indicated on the intertrial interval). Stimuli in this figure are not the originals, but similar stimuli used for illustrative purposes only.</p

Grand-averaged N170 amplitudes (mV) at right occipito-temporal site TP8.

<p>Data are presented as mean and SEM.</p

Effect of tDCS condition on recognition RTs.

<p>For faces encoded while under tDCS influence, the right anodal/left cathodal condition yielded faster recognition RTs than the right cathodal/left anodal (*<i>P</i><0.05) and sham conditions (**<i>P</i><0.01), ∼72 hours after encoding. There was no effect of tDCS on RTs of novel faces.</p

Effects of tDCS condition on grand averaged P3a amplitudes and latencies.

<p>(A) The right anodal/left cathodal condition caused larger P3a amplitudes than the right cathodal/left anodal. This effect was strongest at the second encoding block (displayed, *<i>P</i><0.05). (B) P3a amplitude suppressed from Av1 to Av3 regardless of tDCS condition and block, indicating RS throughout repetitions of stimuli (*<i>P</i><0.05). (C) Effect of tDCS condition x trial average interaction at right dorsolateral site F4 where RS is significant only in the right anodal/left cathodal condition (*<i>P<</i>0.05). (D) The right cathodal/left anodal condition caused a significant delay of P3a at Pz (*<i>P</i><0.05).</p

Contribution of Fatigue to Cognitive Dysfunction in Childhood Acute Lymphoblastic Leukemia Survivors

Late effects such as neurocognitive issues and fatigue have been reported in childhood acute lymphoblastic leukemia (cALL) survivors. Yet, their association is often poorly understood. In this study, we wished to (1) describe neurocognitive difficulties and fatigue in a well-characterized cohort of long-term cALL survivors and (2) explore the risk of having neurocognitive deficits as a function of fatigue. Childhood ALL survivors (N = 285) from three Canadian treatment centers completed the DIVERGT battery of cognitive tests and the PedsQL Multidimensional Fatigue Scale. We performed logistic regressions to assess the risk of a survivor to show cognitive deficits (d = 0.35). The risk for cognitive deficits increased independently with levels of fatigue in the domains of cognitive speed and flexibility, working memory, and verbal fluency. For every 10-point increase on general or sleep/rest fatigue on the 0-100 scale, there was a median +23–35% risk of showing a deficit among the 7 tasks significantly associated with fatigue. Fatigue may constitute a complementary target when searching to mitigate cognitive issues in this population.</p