Ana Defendini, Livia Tomova, Leonie Koban
7 min
This paper by Ana Defendini, Livia Tomova, and Leonie Koban explores how the brain processes social craving—an intense desire for human connection akin to hunger for food or addiction to drugs. Using fMRI brain scans, they test whether a pre-existing Neurobiological Craving Signature (NCS), originally developed for drug and food cravings, also predicts cravings for social interactions. The study leverages an existing dataset where participants underwent 10-hour deprivations: fasting (no food), social isolation (no contact), or baseline (normal conditions). During scans, they viewed and rated cravings for images of food, social scenes (e.g., people interacting), or neutral controls (flowers).
Key insight: The NCS works for social craving, revealing shared brain circuits across primary rewards like food and social bonds. This matters because social isolation and loneliness are linked to severe health risks—depression, addiction, overeating, even higher mortality—yet we lack objective brain-based measures. NCS could become a tool to study how isolation drives maladaptive behaviors.
NCS is a multivariate brain pattern derived from fMRI data, trained on drug and food cue responses to predict subjective craving intensity. Think of it as a 'neural fingerprint' for craving states: specific whole-brain activity patterns light up reliably when someone craves.
In this study, NCS accurately predicted self-reported craving ratings for both food and social cues (but not flowers), validating its generality. Crucially, NCS responses increased after deprivation: stronger for food cues post-fasting, and for social cues post-isolation. This sensitivity to short-term need-states (10h) mirrors how hunger amps up food craving, suggesting NCS tracks motivational drive across reward types.
Social craving is the 'hunger' for interaction, heightened by isolation. The paper draws parallels to addiction: both involve dopaminergic brain regions (e.g., substantia nigra/SN, ventral tegmental area/VTA in the midbrain) that value rewards and drive seeking behavior.
fMRI showed social stimuli activate overlapping networks with food/drug cues, especially under deprivation. Prior work hinted at this (e.g., midbrain responses to 10h isolation mimic fasting), but this is the first whole-brain validation. Hypothesis confirmed: common circuits underlie craving for drugs, food, and social connection—unifying diverse 'primary rewards' essential for survival.
Dataset: Counterbalanced sessions (baseline, fasted, isolated). Participants rated craving (0-100) while viewing cues in an fMRI cue-reactivity paradigm—a standard method to evoke reward responses.
Results:
Robust stats (e.g., multivariate pattern analysis) ensure reliability. Figures illustrate brain maps and deprivation contrasts.
Social isolation (objective lack of contact) and loneliness (subjective unmet needs) fuel mental health crises. NCS offers an objective neuromarker to:
Extends to policy: During pandemics or aging societies, NCS could track population-level craving risks. Future: Apply NCS to other rewards (sex, sleep) or chronic states (long-term loneliness). Bridges psychology, neuroscience, and public health.
Humans are inherently social and seek connection with others for survival. Recent studies suggest that acute social isolation leads to craving for social interactions, but the brain mechanisms of social craving and their relationship to brain networks underlying drug and food craving remain incompletely understood. Here we harnessed an existing dataset and tested whether the Neurobiological Craving Signature (NCS)-a recently developed fMRI-based brain-signature of drug and food craving-also predicts social craving. During fMRI, participants rated their craving for images of food, social interactions, and flowers in three different sessions: after 10h of fasting from food, 10h of social isolation, or neither (baseline; order of sessions counterbalanced). The NCS significantly predicted self-reported craving for food and social cues but not flower cues. Further, NCS responses to food were higher after fasting compared to baseline, and higher for social cues after social isolation compared to baseline, demonstrating its responsiveness to both food and social deprivation. These findings resonate with recent work showing shared brainstem circuits for hunger and social isolation, and indicate shared whole-brain circuits for social, food, and drug craving. They open new avenues for testing the NCS across different primary rewards, for assessing the consequences of their deprivation, and for examining how social deprivation-such as loneliness and isolation-interacts with overeating and drug use.
Alex: So the brain doesn't care if it's food or friends—as long as you're missing something rewarding, the same pattern fires to push you toward any fix.
Sam: Yes, the paper suggests overlapping circuits mean deprivation of one reward—like 10 hours alone—amps up motivation for others via this shared pattern. It points to why isolation might drive overeating or substance use: the brain craves *any* hit. But the authors note this is from short-term tests in healthy adults, so longer loneliness needs more study.
Alex: That overlap makes sense for why people might reach for junk food when lonely. But how did they actually test if this NCS score lines up with what people report feeling?
Sam: They had people view short sets of three similar pictures in a row—like a block of food images such as pizza or cake, or blocks showing friends hanging out, or plain flowers as a neutral check. After each block, participants rated on a simple zero-to-ten scale how much they craved that thing right then, or just how much they liked the flowers. To measure brain activity precisely for each block, researchers used a math tool that isolates the average response during those moments from the rest of the scan noise. Then, to get the NCS score, they compared that isolated image to the NCS pattern by checking how well they overlap—that spits out one number showing how strong the craving pattern is. Across all sessions, higher NCS scores lined up with higher self-reported cravings for both food and social blocks, but not for flowers.
Alex: Did those scores change based on whether people had been fasting or isolated?
Sam: Yes, exactly. The scores went up for food blocks specifically after fasting, and for social blocks after isolation, compared to normal days—but stayed the same for flowers. This shows the pattern is sensitive to missing out on a specific need.
Alex: So short-term isolation flips the switch on social craving the same way hunger does for food.
Sam: The study suggests yes—a common mechanism where lacking one reward boosts the drive for others. That could explain links between loneliness and habits like overeating or turning to drugs, though these were controlled short tests.
Alex: But if it's a shared pattern for all cravings, does it pick up just the intense wanting, or does it react to anything pleasant too—like enjoying a pretty flower?
Sam: That's a key distinction the study tests. Imagine your brain lighting up for two reasons: one for simple pleasure, like noticing a nice smell, and another for a stronger pull, like really needing that thing to feel better. The first is just enjoyment; the second drives you to act, like hunting for food when starving. Researchers separate these by checking if the pattern responds to neutral pleasant things, such as flower pictures where people just rate liking without strong desire. Here, the NCS score stayed low for flowers across all sessions, even after fasting or isolation. But it climbed specifically for food after no eating, and social after no contact—showing it tunes to true craving drive, not basic liking.
Alex: So focusing on the whole brain gives a fuller picture than just one area?
Sam: Exactly. Past work from the same data looked at a deep reward hub called the midbrain—think of it as a basic switchboard low in the brain for expecting goodies like food or friends. They saw it quiet down for non-matching needs after deprivation, like narrowing focus. But the NCS, scanning activity across the entire brain, ramps up for the deprived one—likely blending that focus with thinking and feeling layers.
Alex: With only 30 people scanned, does that limit how widely we can trust these findings?
Sam: Yes, the analysis used data from 30 healthy adults across three sessions each. That's solid for initial tests but small for spotting differences by sex, gender, or personal traits in craving. Larger groups could refine it further. Participants could eat freely during isolation, so the study didn't probe overlaps like boosted food craving from loneliness.
Alex: Fair point—it's a solid starting point, but not the full picture yet. Still, seeing one brain readout generalize across these needs feels like a meaningful step for connecting lab scans to everyday struggles.
Sam: Agreed. This work unifies craving mechanics across rewards, sensitive to even brief lacks, with potential to probe loneliness's toll. Broader validation could guide prevention, but for now, it underscores shared human drives.
Alex: That's a clear takeaway, Sam—thanks for breaking it down so thoughtfully. Thanks for listening to ResearchPod.