With the increasing popularity of smartphones in the past decades, the physical, social, and psychological consequences of excessive smartphone use (ESU) have been increasingly debated. Cue-reactivity (CR) has been discussed as a core mechanism driving this behavior, and previous studies have highlighted distinct neural mechanisms underlying CR in individuals with ESU. Understanding the neural basis of ESU is crucial for developing effective interventions and prevention strategies to mitigate its negative impact on mental health and daily functioning.

Here, we used a functional MRI (fMRI) CR-paradigm to investigate the effects of smartphone restriction over 72 hours in 25 young adult smartphone users. The CR-task used contrasts of images showing smartphones vs. neutral stimuli and active vs. inactive smartphones. By analyzing these contrasts, we aimed to determine how brain activity patterns change in response to smartphone-related cues and whether these changes reflect alterations in craving, reward processing, and self-control mechanisms.

Region-of-interest-based correlations with psychometric scores were performed, and activity changes after 72 hours were investigated on a neurochemical level using neurotransmitter probability maps. Our findings revealed that CR-related brain activity changes over time were most prominent in the nucleus accumbens and anterior cingulate cortex (p < 0.001), two regions heavily implicated in reward processing and habit formation. Such changes were significantly associated with dopamine- and serotonin-receptor probabilities (pFDR < 0.05), suggesting a potential neurochemical basis for ESU-related compulsive behaviors.

Furthermore, significant associations between parietal cortex activity and craving were detected (p < 0.05), emphasizing the role of attentional control and sensory processing in smartphone addiction. The observed neural adaptations indicate that even short-term smartphone restriction can lead to measurable changes in brain function, potentially altering reward sensitivity and self-regulatory processes.

This study provides evidence for CR-related modulation of neural activity in key regions of salience, motor-inhibition, and reward processing after 72 hours of smartphone restriction. These findings suggest that prolonged smartphone abstinence may trigger neural plasticity in circuits linked to craving and impulse control, shedding light on the underlying neurobiological mechanisms that contribute to excessive smartphone use. The identified neural mechanisms may substantially promote addictive behavior in people at risk for ESU, highlighting the need for further research into targeted interventions that address both behavioral and neurochemical aspects of smartphone addiction.