Frailty and hypertension are among the most prevalent and clinically consequential conditions in aging populations. Hypertension is more prevalent among older adults, and blood pressure (BP) is measured more frequently in this population than in younger individuals. Evidence on the relationship between BP indices and frailty is therefore of considerable interest to both clinicians and researchers. Indeed, BP variability (BPV) has been increasingly recognized as a marker of adverse outcomes beyond cardiovascular disease (CVD),¹ and understanding the mechanisms linking BPV to frailty may have broad implications for the management of aging populations.

In this issue of Polish Archives of Internal Medicine, Croce et al² report their findings from a cross‑sectional study investigating the association between short‑term BPV and frailty in 184 hypertensive outpatients aged 75 years or older. Using 24‑hour ambulatory blood pressure monitoring (ABPM) and a 40‑item frailty index (FI) derived from comprehensive geriatric assessment (CGA), the authors showed that nocturnal BPV, specifically the night‑time diastolic SD, was independently associated with higher FI scores after multivariable adjustment. In addition, reduced nocturnal dipping in systolic BP was associated with frailty, suggesting that a nondipping pattern may be linked to a higher frailty burden.

The study population consisted exclusively of very old hypertensive outpatients (mean age, 81.8 y), a population that is largely underrepresented in clinical trials and observational research. The use of the validated Italian FI, constructed from CGA data, further strengthens the clinical rigor of the study. These strengths suggest that, when ABPM is performed in this population, assessment of night‑time BPV and nocturnal BP status may be informative for detecting frailty. To explore the present findings further, examining interactions among dipping status, BP level, and short‑term BPV may enhance the accuracy of frailty detection. For example, the combination of a nondipping pattern with elevated nocturnal BPV may identify older adults with a particularly high frailty burden.

The mechanisms underlying the association between nocturnal BPV and frailty warrant further consideration. With respect to nocturnal diastolic BPV in particular, the authors note that diastolic BP may be especially sensitive to alterations in vascular tone and autonomic function in older adults.² Meanwhile, a contribution from systolic BPV cannot be fully excluded, as night‑time systolic BPV also showed a positive association with frailty that did not reach significance. Short‑term BPV is a modest but independent risk factor for CVD.^1,3,4 Because the FI used by Croce et al² included items reflecting CVD history, CVD may serve as a mediator in the pathway linking BPV to frailty. Therefore, increased BPV may contribute to vascular and organ damage, which in turn elevates the frailty burden.

Due to the cross‑sectional design, the possibility of reverse causality must be considered. The participants with greater frailty had more comorbidities,² which may have impaired their ability to maintain stable BP. Among other indices captured by ABPM, the finding that night‑time heart rate was higher in the participants with greater frailty is of interest.² This may reflect enhanced nocturnal sympathetic activity. Although the analyses were adjusted for insomnia diagnosis, poor sleep quality that is not fully captured by a binary diagnosis of insomnia may further activate the sympathetic nervous system during sleep. Because nocturia has been reported to contribute to nocturnal BP elevation,⁵ night‑time awakenings due to nocturia or other symptoms may also play a role. Given the limitations of the cross‑sectional design, prospective studies considering these potential mediating and confounding factors are needed to clarify the underlying mechanisms.

It is also worth noting that the association between BPV and frailty is not limited to short‑term variability. Accumulating evidence suggests that long‑term, visit‑to‑visit BPV is also associated with frailty risk.^6,7 In a 5‑year prospective study, Rouch et al⁶ demonstrated that higher visit‑to‑visit systolic BPV was significantly associated with incident frailty in community‑dwelling older adults, supporting the concept of physiological BP dysregulation as an underlying mechanism. Similarly, Fravel et al⁷ reported that high visit‑to‑visit systolic BPV, independent of mean BP level, was associated with an increased risk of incident frailty over up to 9 years of follow‑up. However, in both studies, diastolic BPV was not consistently associated with frailty.^6,7 This may reflect fundamentally different underlying mechanisms between short‑term and long‑term BPV. Furthermore, differences in study populations and designs may also contribute to these discrepancies, and future studies directly comparing short‑term and long‑term BPV within the same individuals are warranted.

Dementia is another co‑occurring public health concern in older populations, and is also known to be associated with higher BPV.^1,8-10 We have previously reported that visit‑to‑visit and day‑to‑day BPV are each associated with the risk of cognitive decline.^8-10 Notably, these BPV components are associated with dementia or cognitive function irrespective of antihypertensive medication use.^8,9 Taken together with the present study by Croce et al² and other reports that have examined frailty as an outcome, BPV may serve as an indicator of biological aging in older adults. From this perspective, further development of wearable and other novel devices capable of capturing both short‑term and long‑term BPV would be valuable. Such tools could enable earlier detection of accelerated aging or aging‑related complications in older populations.

In summary, the study by Croce et al² represents an important and timely contribution to the emerging literature on BPV and frailty in older adults. By rigorously characterizing this association in a very old hypertensive population that is typically underrepresented in clinical research, the authors provide evidence suggesting that ABPM‑derived indices may carry information beyond conventional cardiovascular risk stratification.