A firm handshake is often seen as a sign of vitality and self-confidence. Yet beyond social convention, the strength of our hands may carry information that runs much deeper: it could serve as a window into our brain and our mental state. In modern psychiatry, there is growing interest in physical markers—so-called biomarkers—that can be measured objectively and help to better understand complex psychological conditions. How is it possible that a simple test using a hand dynamometer can provide deeper insights into disorders such as depression and schizophrenia? A groundbreaking study by von Känel et al. (2026) explored this question and offers compelling evidence that our muscular strength is inseparably intertwined with our mental well-being.
The Surprising Hierarchy of Strength
The study, which included a total of 533 participants across two sites, clearly demonstrates that mental state is directly correlated with physical performance. Notably, the results revealed a surprising hierarchy in grip strength measurements. One key point to highlight: the researchers found that inpatient status—whether a patient was hospitalized or not—was not a significant predictor of grip strength. This suggests that reduced physical strength is not merely a consequence of limited activity in a clinical setting, but rather an intrinsic feature of the disorder itself.
While the healthy control group achieved the highest values, significant differences emerged between the patient groups. Surprisingly, patients with schizophrenia performed markedly better than those with depression. The data (mean values of the dominant hand) clearly illustrate this hierarchy:
- Healthy Control Participants (HC): 30,7 kg
- Schizophrenia Group: 29,4 kg
- Remitted Depression (rMDD): 24,5 kg
- Current Depression (cMDD): 23,7 kg
Although grip strength in patients with schizophrenia was lower than in healthy individuals, it remained significantly higher than in both depression groups. This underscores that different psychiatric diagnoses leave distinct signatures in motor function.
Depression Leaves Its Mark — Even After Recovery
One of the most significant findings of the study concerns the group of individuals with remitted depression (rMDD). One might assume that as the depressive episode subsides, physical strength would return to normal. However, the data tell a different story: grip strength in previously depressed individuals remained at the same low level as in those who were currently affected.
This suggests that a clinical improvement in mood does not necessarily entail a full restoration of psychomotor functioning. Researchers interpret this as evidence of “residual symptoms”—in other words, lasting imprints of the disorder that remain in the system like a kind of scar.
"In depression, persistent reductions during remission may reflect residual symptoms, such as psychomotor or executive dysfunction, indicating that remission does not fully normalize psychomotor performance." (von Känel et al, 2026).
This incomplete normalization suggests that psychomotor slowing and the associated reduction in strength may be more deeply rooted than the subjective psychological experience of recovery might imply.
Motivation Is a Motor Function
In schizophrenia, grip strength reveals a different facet of the disorder. Here, reduced strength was strongly correlated with so-called negative symptoms, as measured by the BNSS (Brief Negative Symptom Scale). The association was particularly pronounced in the domains of avolition (lack of motivation), affect (blunted emotional expression), and alogia (poverty of speech).
The biological component underlying this is fascinating: it is primarily a matter of a “translation problem.” The researchers hypothesize that disruptions in fronto-striatal circuits and dopaminergic dysfunction are at the root of this phenomenon. These systems act as a bridge, converting the brain’s “motivational drive” into actual “motor output,” that is, muscular force. It is not that the patients’ muscles are inherently too weak; rather, the neural command center appears unable to effectively transmit the signal to “grip firmly” to the periphery when motivational drive is impaired.
The Gender Trap: Why Men Respond Differently
A particularly intriguing aspect of the study is its sex-specific pattern. Significant correlations between the severity of clinical symptoms and grip strength were found primarily in men.
The data show a correlation of ρ = −0.28 in men with schizophrenia and an even stronger association of ρ = −0.48 in men with depression. In contrast, these correlations were not significant in women. This points to a potential “gender trap” in diagnostics: because motor performance and symptom expression are less tightly linked in women, clinicians may underestimate the severity of a disorder if they rely too heavily on physical markers. Therefore, accounting for sex differences is essential for the accurate interpretation of biomarkers in psychiatry.
A Low-Cost Glimpse into the Future
Grip strength proves to be a valuable transdiagnostic biomarker that provides reliable data across different disorders. Its advantages in clinical practice are clear: the measurement is simple, reliable, and highly cost-effective. It offers an objective way to assess motor and motivational deficits that are often difficult to capture through purely subjective patient reports.
The finding that these deficits persist even during remission makes grip strength a potential tool for the long-term monitoring of treatment outcomes. This raises the question of whether the hand dynamometer might one day become as standard in psychiatric practice as the stethoscope is in primary care.
References
von Känel S, Pavlidou A, Nadesalingam N, et al. Transdiagnostic Patterns of Grip Strength in Schizophrenia, Current Depression, and Remitted Depression. JAMA Psychiatry. Published online March 18, 2026. doi:10.1001/jamapsychiatry.2026.0144 URL: https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2846480
See also the article in the Deutsches Ärzteblatt of April 16, 2026: https://www.aerzteblatt.de/news/rubriken/medizin/auch-nach-uberstandener-depression-bleibt-die-handkraft-vermindert-c27804e5-ab4c-4dd1-807b-bc9b1686a39a
