Reduced gray matter and altered brain connectivity are linked to problematic smartphone use

A comprehensive review of neuroimaging research suggests that problematic smartphone use is associated with distinct structural and functional alterations in the brain. These changes primarily involve neural circuits responsible for reward processing, executive control, and emotional regulation.

The analysis indicates that the intense motivational pull of smartphones may stem from how these devices tap into the brain’s social cognition networks, reinforcing habits through digital social feedback and the avoidance of social exclusion. These findings were published in the journal Progress in Neuro-Psychopharmacology and Biological Psychiatry.

Smartphone usage has become ubiquitous globally, integrated into almost every aspect of modern daily life for billions of people. While these devices offer numerous benefits in communication and information access, excessive engagement has been linked to negative outcomes in some individuals, including sleep disturbances, heightened anxiety, and reduced cognitive performance.

Scientists have increasingly viewed this phenomenon through the lens of behavioral addiction, prompting numerous studies into the underlying neurobiology. The researchers behind the current paper aimed to synthesize the growing body of neuroimaging data to better understand the brain mechanisms driving problematic smartphone use.

“Problematic smartphone use is increasingly discussed as a clinically relevant behavioral pattern, yet its neurobiological basis remains incompletely understood. Existing research has identified structural and functional brain alterations, but the field is still characterized by conceptual heterogeneity, varying terminology, and a limited integration of neuroscientific findings with psychologically meaningful models,” said study author Robert Christian Wolf, deputy director of the Department of General Psychiatry at Heidelberg University Hospital.

“We were particularly struck by the fact that, despite the inherently social nature of smartphone use, social cognitive mechanisms have received comparatively little attention in neuroimaging research on problematic smartphone use. This review was motivated by the need to systematically synthesize current multimodal imaging findings and to place them within a broader framework that incorporates social reinforcement, fear of missing out, and sensitivity to social exclusion.”

The researchers searched the PubMed database for peer-reviewed scientific papers published between January 2015 and April 2025. The search focused on studies using neuroimaging techniques to examine individuals exhibiting problematic or excessive smartphone use compared to control groups. To measure the severity of smartphone habits, researchers across the reviewed studies primarily relied on established psychological questionnaires, most notably the Smartphone Addiction Scale and the Smartphone Addiction Proneness Scale.

The review synthesized data from two primary types of brain scans: structural imaging, which maps the physical architecture and anatomy of the brain, and functional imaging, which measures brain activity over time by detecting changes in blood flow related to neural firing. The final analysis included 35 studies, comprising 9 looking at static brain structure, 24 examining brain function during various cognitive tasks or while at rest, and 2 additional studies that employed both structural and functional imaging techniques.

Across these studies, structural imaging sample sizes ranged from 19 to 266 participants, while functional imaging samples ranged from 16 to 162 individuals. The participants ranged in age from 13 to 30 years old.

The review identified consistent patterns across structural imaging studies. Individuals exhibiting problematic smartphone use tended to show reduced gray matter volume in specific brain areas, including the insular cortex, the anterior cingulate cortex, and the orbitofrontal cortex. The insular cortex is involved in emotional awareness and regulating the body’s internal states, while the orbitofrontal cortex plays a role in decision-making and assigning value to rewards. Additionally, studies using diffusion tensor imaging, which maps white matter tracts, suggested alterations in the neural pathways connecting frontal brain regions to limbic areas involved in emotion.

Functional imaging studies provided further insights into cognitive processing in affected individuals. When their brains were scanned in a resting state without a specific task, they showed altered connectivity within networks responsible for attention and executive control. When faced with tasks requiring high cognitive effort, individuals with problematic use frequently demonstrated reduced activation in prefrontal control regions. This pattern suggests a diminished capacity to inhibit impulses or maintain focus under demanding conditions.

In contrast, when presented with smartphone-related cues, such as notifications or pictures of the device, their brains showed heightened activity in reward-processing circuits. These neural responses to smartphone cues appear similar to patterns seen in substance use disorders, indicating conditioned associations between the device and gratification. The review also found evidence of altered emotional processing, with some studies showing different neural responses to facial expressions compared to control groups.

A significant aspect of the review focused on the role of social cognition in driving problematic use. The researchers found evidence that social and emotional factors, such as the fear of missing out or sensitivity to social exclusion, are linked to distinct neural responses.

For example, one study found that a simulated experience of social rejection in a scanning environment elicited stronger activation in brain areas associated with processing social pain among those with problematic use patterns. The researchers suggest that smartphones act as powerful interfaces connecting reward processing with social interaction. The brain may become hypersensitive not just to the device, but to the anticipation of social feedback it provides.

“One notable observation was how limited the neuroimaging literature remains with regard to explicitly social cognitive processes, despite the fact that smartphone use is deeply embedded in social interaction,” Wolf told PsyPost. “This is particularly striking because constructs such as fear of missing out and sensitivity to social exclusion appear highly relevant for understanding why smartphone cues become motivationally powerful. Another important point was the degree of overlap between neural systems engaged by cue reactivity and those involved in social reward and social pain. This supports the view that the reinforcing properties of smartphones may be driven to a substantial extent by their social significance.”

The scientists interpreted these findings through a theoretical framework known as the I-PACE model, which posits that problematic behaviors result from interactions among individual predispositions, emotional states, and cognitive control mechanisms. The review proposes expanding this model to emphasize how socially relevant rewards and digital feedback drive habitual behavior.

“Our findings suggest that problematic smartphone use should not be reduced to a simple matter of weak willpower or excessive screen time,” Wolf explained. “Rather, it appears to emerge from an interaction between altered reward sensitivity, reduced executive control, affective vulnerability, and cognitive biases, particularly in socially salient digital contexts. Smartphone related cues do not merely capture attention because of the device itself, but because they are often linked to social feedback, reward expectation, and the avoidance of exclusion. This may help explain why smartphone use can become repetitive, difficult to regulate, and emotionally charged in some individuals.”

“The practical significance of the findings lies less in any single isolated effect and more in the convergence across structural, functional, neurochemical, and longitudinal studies. Across modalities, the reviewed literature repeatedly implicates frontostriatal and frontolimbic circuits involved in executive control, reward processing, affect regulation, and social cognition. This convergence strengthens the interpretation that problematic smartphone use is associated with meaningful alterations in neurocognitive systems relevant to self-regulation and reinforcement.”

“Importantly, these insights may inform prevention and intervention strategies grounded in biobehavioral models, by identifying neural and psychological mechanisms that sustain maladaptive patterns of smartphone use.”

The researchers note that this field of study is still developing and faces certain limitations. A primary issue with the existing research is that most studies use a cross-sectional design, capturing a single snapshot in time. This methodology makes it difficult to determine whether the observed brain differences cause problematic smartphone use or are a result of prolonged overuse. Additionally, Wolf noted that their findings do not imply that typical smartphone engagement is inherently unhealthy.

“A central caveat is that problematic smartphone use is not formally recognized as a disorder, and our review does not imply that everyday or even frequent smartphone use should be pathologized,” Wolf told PsyPost. “We advocate a dimensional perspective that distinguishes normative use from maladaptive patterns characterized by impaired control, continued use despite negative consequences, and functional impairment. In addition, most available studies are cross sectional, which means that causal relationships cannot yet be determined with confidence. Neural alterations observed in individuals with problematic smartphone use may therefore reflect vulnerability factors, consequences of prolonged use, or reciprocal processes developing over time.”

To address current limitations, the investigators recommend that future research prioritize longitudinal studies tracking participants over time to better understand developmental paths and causality. They also suggest a stronger experimental focus on how social contexts influence brain responses to smartphone cues.

“A major next step is to investigate more directly how smartphone related cue reactivity interacts with social cognitive processes under controlled experimental conditions,” Wolf said. “In particular, it will be important to examine whether neural responses to smartphone cues differ depending on whether these cues are embedded in socially meaningful versus non-social contexts. More longitudinal and interventional studies will also be essential to clarify developmental trajectories, causal mechanisms, and potential neural changes following restriction or therapeutic interventions.”

“In the longer term, this line of research may help refine prevention and intervention strategies that address not only craving and impulsivity, but also maladaptive interpretations of digital social feedback and vulnerability to social exclusion.”

“One broader implication of the review is that smartphones may represent a particularly powerful interface between reward processing and social cognition,” Wolf added. “They provide immediate and repeated access to socially relevant cues that can engage neural systems involved in salience attribution, belonging, and self-regulation with unusual frequency. From a research perspective, problematic smartphone use therefore offers an informative model for studying how digital environments shape behavior through the interaction of neurobiological, cognitive, and social mechanisms. We hope that this review contributes to a more differentiated and scientifically grounded discussion of problematic smartphone use.”

The study, “Screens and brains: multimodal neuroimaging insights into mechanisms of problematic smartphone use,” was authored by Nadine D. Wolf, Gudrun M. Henemann, Mike M. Schmitgen, Julian Koenig, Patrick Bach, and Robert C. Wolf.