Neural correlates of cognitive fatigue in problematic smartphone users: A task-based fMRI study

The widespread use of smartphones, particularly among young adults, has raised concerns about their impact on cognitive functioning, leading to a growing interest in understanding the neurobiological underpinnings of problematic smartphone use (PSU). Despite evidence linking PSU to negative cognitive and emotional outcomes, the neurobiological mechanisms underlying cognitive impairments in PSU individuals remain underexplored. This study aimed to investigate the relationship between cognitive fatigue (CF) and brain activity in individuals with PSU. Eighty-one healthy adults underwent functional magnetic resonance imaging (fMRI) while performing cognitively demanding tasks designed to induce CF. Brain activation patterns, functional connectivity, and correlations with behavioral performance and self-reported fatigue were analyzed using brain imaging analyses. The PSU group showed significant activation in the ventromedial prefrontal cortex (vmPFC) compared to the non-problematic smartphone use (nonPSU) group, and vmPFC activity was positively correlated with fatigue scores. In addition, there was also an increase in functional connectivity between the vmPFC and left middle frontal gyrus (MFG) in the PSU group. Correlations between task performance and activation in the nucleus accumbens (NAcc) and middle cingulate cortex (MCC) further indicated the engagement of compensatory mechanisms related to reward sensitivity and cognitive control. These results define specific neural markers of cognitive fatigue in people with PSU, indicating that increased activity and connectivity in key brain areas require greater cognitive resources to maintain functioning. Therefore, this highlights the need for targeted interventions to minimize cognitive fatigue and mitigate the neurocognitive impact of PSU.