Extensive comparison of salivary collection, transportation, preparation, and storage methods: a systematic review

BACKGROUND

Human saliva as a bodily fluid-similar to blood-is utilized for diagnostic purposes. Unlike blood sampling, collecting saliva is non-invasive, inexpensive, and readily accessible. There are no previously published systematic reviews regarding different collection, transportation, preparation, and storage methods for human saliva.

DESIGN

This study has been prepared and organized according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) 2020 guidelines. This systematic review has been registered at PROSPERO (Registration ID: CRD42023415384). The study question according to the PICO format was as followed: Comparison of the performance (C) of different saliva sampling, handling, transportation, and storage techniques and methods (I) assessed for analyzing stimulated or unstimulated human saliva (P and O). An electronic search was executed in Scopus, Google Scholar, and PubMed.

RESULTS

Twenty-three descriptive human clinical studies published between 1995 and 2022 were included. Eight categories of salivary features and biomarkers were investigated (i.e., salivary flow rate, total saliva quantity, total protein, cortisol, testosterone, DNA quality and quantity, pH and buffering pH). Twenty-two saliva sampling methods/devices were utilized. Passive drooling, Salivette®, and spitting were the most utilized methods. Sampling times with optimum capabilities for cortisol, iodine, and oral cancer metabolites are suggested to be 7:30 AM to 9:00 AM, 10:30 AM to 11:00 AM, and 14:00 PM to 20:00 PM, respectively. There were 6 storage methods. Centrifuging samples and storing them at -70 °C to -80 °C was the most utilized storage method. For DNA quantity and quality, analyzing samples immediately after collection without centrifuging or storage, outperformed centrifuging samples and storing them at -70 °C to -80 °C. Non-coated Salivette® was the most successful method/device for analyzing salivary flow rate.

CONCLUSION

It is highly suggested that scientists take aid from the reported categorized outcomes, and design their study questions based on the current voids for each method/device.

Normal salivary production using a swab method in clinical settings

Objectives

The purpose of the study was to generate age‐ and gender‐based normative data for unstimulated salivary flow rate (uSFR) by means of a swab method, and to provide preliminary results of using the test in patients suspected of reduced salivary function.

Methods

The 130 healthy participants without subjective xerostomia or suspicion of reduced salivation were recruited. Measurements of uSFR were conducted three times per subject and mean uSFR was calculated for the entire population and stratified according to age and gender. The method was applied in a pilot population of 25 patients suffering from either Sjögren's syndrome or had underwent irradiation of the head and neck.

Results

Mean uSFR in the healthy group was 0.808 g/min (range: 0.165–2.442). Not significant trends towards declining uSFR with increasing age and higher uSFR in women were seen. Mean uSFR in the patients was 0.429 g/min (range: 0.111–1.448), which was significantly lower than normative values. Use of xerogenic drugs correlated to lower uSFR.

Conclusion

Age‐ and gender‐based normative data of uSFR was presented using a fast and readily implementable swab test. The test was able to objectively verify hyposalivation among patients suffering from Sjögren's syndrome or having been exposed to head and neck radiation.

The Impact of Music on Stress Biomarkers: Protocol of a Substudy of the Cluster-Randomized Controlled Trial Music Interventions for Dementia and Depression in ELderly Care (MIDDEL)

Recently, a large cluster-randomized controlled trial was designed-Music Interventions for Dementia and Depression in ELderly care (MIDDEL)-to assess the effectiveness of music interventions on depression in care home residents with dementia (ClinicalTrials.gov NCT03496675). To understand the pathophysiological mechanisms, we observed the effect of repeated music interventions on stress in this population since chronic stress was associated with depression and an increased risk for dementia. An exploratory study was designed to assess: (1) changes in hair cortisol concentrations as an indicator of longer-term stress; (2) whether baseline stress is a predictor of therapy outcome; (3) pre- and post-treatment effects on salivary α-amylase and cortisol response as an indicator of immediate stress in 180-200 care home residents with dementia and depressive symptoms who partake in the MIDDEL trial. Insights into mediatory effects of stress to explain the effect of music interventions will be gained. Hair cortisol concentrations were assessed at baseline and at 3, 6, and 12 months along with the Perceived Stress Scale. Salivary α-amylase and cortisol concentrations were assessed at 1, 3, and 6 months. Saliva was collected just before a session and 15 and 60 min after a session, along with a stress Visual Analogue Scale.

The Feasibility and Acceptability of In-Home Saliva Collection for Stress in Persons With Dementia and Their Family Caregivers

BACKGROUND

Although increasing attention is being paid to cortisol and the sulfated form of dehydroepiandrosterone (DHEA-S) as stress biomarkers, the feasibility of saliva collection of such biomarkers has yet to be investigated among dementia care dyads (persons with dementia [PWD] and family caregivers) living in a home setting. We explored the feasibility and acceptability of in-home saliva collection for cortisol and DHEA-S as stress biomarkers among dementia care dyads.

METHODS

Dementia care dyads were recruited from a memory evaluation center. After pre-evaluation and education sessions, participants collected their saliva 3 times a day, 5 days a week, for 8 consecutive weeks. We calculated frequency counts and percentages to assess enrollment rate, retention rate, the completion rate of saliva collection, and valid samples of cortisol and DHEA-S. Independent samples t-tests were performed to compare mean differences in the total number of collected samples and valid samples between PWD and family caregivers at each time point of saliva collection.

RESULTS

A total of 46 dyads were referred to this study; 32 dyads (69.6%) agreed to participate, and 26 started collecting saliva. Twenty-four dyads (75%) completed 8 weeks of saliva collection. There were no significant differences (p > 0.05) in the number of collected samples and valid samples between PWD and caregiver participants.

CONCLUSION

This study supports the feasibility of in-home saliva collection for stress biomarker assay and the need for further investigation into self-administered collection of stress biomarkers with a particular focus on dementia care dyads living at home.

A Randomized Controlled Trial Examining the Effect of Acupressure on Agitation and Salivary Cortisol in Nursing Home Residents with Dementia

BACKGROUND

Acupressure has been used to manage agitation in people with dementia because it is safe and inexpensive. However, its effect on agitation and at the biochemical level is uncertain.

METHODS

This randomized controlled trial examined the effect of acupressure on agitation, as measured by the Cohen-Mansfield Agitation Inventory (CMAI); and on salivary cortisol, as measured at baseline (T0) and in the 3rd (T1), 5th (T2), and 8th (T3) weeks. There were 119 agitated residents with dementia randomized into 3 groups: acupressure (n = 39), sham (n = 41), and usual-care group (n = 39).

RESULTS

A downward trend in agitation over time was noted in the acupressure group, which almost reached a level of significance in interaction effects between groups and time points (p = 0.052). Post hoc pairwise tests in the acupressure group showed that acupressure significantly reduced agitation at T2 (mean difference -6.84, 95% CI -10.60, -3.08) compared to baseline. Significant interaction effects between groups and time points were observed on the level of salivary cortisol (p = 0.022).

CONCLUSION

Acupressure is a multicomponent intervention that can reduce agitation. Acupoint activation may not be a significant component in reducing agitation, although this result may have been limited by the inadequate sample size. Acupressure is effective in reducing salivary cortisol in people with dementia.

Stress in Persons with Dementia: Benefits of a Memory Center Day Program

Most persons with dementia are cared for by family members who are so overwhelmed that their mental and physical health declines. Adult day care programs (ADC) are growing in number to meet caregivers' needs for respite but little is known about their effect on enrollee mental health. We examined mental health of enrollees (stress, anxiety, mood, emotions) and arousal (blood pressure and salivary cortisol) from day program enrollment to 3 months following enrollment. Results showed significant decreases in morning cortisol level at 1 and 3 months (p=.047). Perceived stress decreased at 1 and 3 months measured by Perceived Stress Scale (p=.03) and Index of Clinical Stress (p=.01). Results provide support for ADC as a stress-reducing environment for individuals with mild to moderate cognitive impairment. Future studies should be conducted to examine which elements of ADC are beneficial.

The Effect of Acupressure on Agitation and Salivary Cortisol in People with Dementia: A Pilot Study

OBJECTIVES

This study aimed to identify the acupressure effect over time, compare the efficacy in different dosages, and identify feasibility issues with saliva sample collection and acupressure implementation in agitated nursing home residents with dementia.

DESIGN

Time serial design with eight dosage-combination groups.

SETTING

Three residential care homes (RCHs) in Hong Kong.

PARTICIPANTS

Agitated RCH residents with dementia.

INTERVENTIONS

Acupressure was performed for 9 minutes altogether on five acupoints: Fengchi (GB 20), Baihui (GV 20), Shenmen (HT 7), Niguan (PC 6), and Yingtang (EX-HN 3). Two frequencies (once and twice a day) and four durations (1, 2, 3, and 4 weeks) formed eight dosage combinations.

OUTCOME MEASURES

The primary outcome was agitation, measured by the Cohen Mansfield Agitation Inventory. The secondary outcome was stress, measured by salivary cortisol.

RESULTS

Twenty-four participants from three RCHs completed the study. Acupressure was successfully completed for 88% of total sessions, and 79.17% of participants completed more than 80% of expected sessions. The effect of acupressure on agitation onset was seen immediately at week 1 (p < 0.001), resurged at week 4 (p = 0.001), and was sustained until week 6 (p < 0.001). The effect on stress began immediately to a mild extent at week 1 (p = 0.011) and peaked at week 4 (p = 0.010). Acupressure was observed to show the largest effect when it was performed twice a day (p = 0.026) for 2 weeks (p = 0.005). Valid saliva samples were collected for 53.33% of participants. Hyposalivation caused this unsatisfactory yield of valid saliva samples.

CONCLUSION

Acupressure can be conducted on agitated RCH residents with dementia, but low yield of saliva samples related to participants' hyposalivation is a problem. Preliminary findings suggest that acupressure is effective in reducing both agitation and stress. Its onset of effect was immediate, and the effect was sustained until 6 weeks after the intervention. The optimal dosage appears to be a course of acupressure twice a day for 2 weeks.

How to accommodate women with mobility limitations in biological studies

People with disabilities should be routinely included in research studies if there is no specific reason for their exclusion. Regardless, they may be inadvertently excluded because of the procedures of the study. By conducting a community-based biological study with women aging with mobility limitations, these authors gained further understanding of their accommodation needs during research participation. The women aging with mobility limitations offered specific physical, cultural, or environmental needs that could have influenced the methods, procedures, and possible outcomes involved when conducting a biological study with this community living population. The authors and participants identified methodological challenges for women with mobility impairments within three key areas: recruitment procedures, laboratory procedures, and community-based data collection. The authors propose possible solutions to these identified challenges. It is our hope that this will begin a larger dialogue on how to routinely accommodate people with disabilities in biological research studies.

Association of Job Strain With Cortisol and Alpha-Amylase Among Shift-Working Health Care Professionals in Laboratory and Field

Although the prevalence of work-related stress has increased, knowledge on the contributions of that stress to long-term adverse health effects is still lacking. Stress biomarkers can reveal early signs of negative health effects, but no previous studies have measured both acute stress reactions and long-term exposure to job strain using both salivary cortisol and α-amylase (AA). The present study examines the association between job strain and these biomarkers among shift-working female health care professionals in the laboratory and the field. The 95 participants were recruited from hospital wards categorized in either the top (high job strain [HJS] group, n = 42) or the bottom quartile of job strain (low job strain [LJS] group, n = 53), as rated by survey responses. Participants’ self-perceived job strain was at least as high or low as the ward’s average estimation. Saliva samples were collected during the Trier Social Stress Test (TSST), preselected morning and night shifts, and a day off. There was a larger increase in the cortisol concentration of participants in the HJS than in the LJS group (2.27- vs. 1.48-fold, respectively, nonsignificant) during the TSST. Participants in the HJS group also had higher salivary AA levels 30 min after awakening on the morning-shift day than those in the LJS group ( p = .02), whereas the salivary cortisol awakening response on the day off was higher in the LJS group ( p = .05, education as a covariate). The remaining stress-biomarker results did not differ significantly between groups. These data suggest that HJS in shift-working health care professionals is weakly associated with changes in stress biomarkers.

Is this elderly patient dehydrated? Diagnostic accuracy of hydration assessment using physical signs, urine, and saliva markers

OBJECTIVES

Dehydration in older adults contributes to increased morbidity and mortality during hospitalization. As such, early diagnosis of dehydration may improve patient outcome and reduce the burden on healthcare. This prospective study investigated the diagnostic accuracy of routinely used physical signs, and noninvasive markers of hydration in urine and saliva.

DESIGN

Prospective diagnostic accuracy study.

SETTING

Hospital acute medical care unit and emergency department.

PARTICIPANTS

One hundred thirty older adults [59 males, 71 females, mean (standard deviation) age = 78 (9) years].

MEASUREMENTS

Participants with any primary diagnosis underwent a hydration assessment within 30 minutes of admittance to hospital. Hydration assessment comprised 7 physical signs of dehydration [tachycardia (>100 bpm), low systolic blood pressure (<100 mm Hg), dry mucous membrane, dry axilla, poor skin turgor, sunken eyes, and long capillary refill time (>2 seconds)], urine color, urine specific gravity, saliva flow rate, and saliva osmolality. Plasma osmolality and the blood urea nitrogen to creatinine ratio were assessed as reference standards of hydration with 21% of participants classified with water-loss dehydration (plasma osmolality >295 mOsm/kg), 19% classified with water-and-solute-loss dehydration (blood urea nitrogen to creatinine ratio >20), and 60% classified as euhydrated.

RESULTS

All physical signs showed poor sensitivity (0%-44%) for detecting either form of dehydration, with only low systolic blood pressure demonstrating potential utility for aiding the diagnosis of water-and-solute-loss dehydration [diagnostic odds ratio (OR) = 14.7]. Neither urine color, urine specific gravity, nor saliva flow rate could discriminate hydration status (area under the receiver operating characteristic curve = 0.49-0.57, P > .05). In contrast, saliva osmolality demonstrated moderate diagnostic accuracy (area under the receiver operating characteristic curve = 0.76, P < .001) to distinguish both dehydration types (70% sensitivity, 68% specificity, OR = 5.0 (95% confidence interval 1.7-15.1) for water-loss dehydration, and 78% sensitivity, 72% specificity, OR = 8.9 (95% confidence interval 2.5-30.7) for water-and-solute-loss dehydration).

CONCLUSIONS

With the exception of low systolic blood pressure, which could aid in the specific diagnosis of water-and-solute-loss dehydration, physical signs and urine markers show little utility to determine if an elderly patient is dehydrated. Saliva osmolality demonstrated superior diagnostic accuracy compared with physical signs and urine markers, and may have utility for the assessment of both water-loss and water-and-solute-loss dehydration in older individuals. It is particularly noteworthy that saliva osmolality was able to detect water-and-solute-loss dehydration, for which a measurement of plasma osmolality would have no diagnostic utility.

Incorporating salivary biomarkers into nursing research: an overview and review of best practices

Analytes and biomarkers present in saliva may provide insight into individual differences in environmental chemical exposures, variation in reproductive hormones, therapeutic and illegal substance use, changes in stress-related physiology, and the immunologic footprints of infectious disease. The wealth of information provided by salivary analytes has the potential to enrich biobehavioral nursing research by enabling researchers to measure these individual differences in the clinic as well as in patients' and participants' everyday social worlds. In this article, the authors provide a roadmap for researchers new to this area who would like to learn more about integrating salivary biospecimens into the next generation of health research. In addition, the authors highlight best practices and strategies to avoid common pitfalls for researchers already engaged in this field.

Can a licorice lollipop decrease cariogenic bacteria in nursing home residents?

The purpose of this pilot study was to examine whether an herbal lollipop containing licorice root decreases Streptococcus mutans (S. mutans) bacteria that cause dental caries in nursing home residents. A total of 8 residents (5 women, 3 men; mean age = 85) consented to participate in this study. Participants were offered two lollipops per day for 21 days. Saliva samples were collected at baseline and Days 1, 3, 7, 14, and 21, then analyzed for numbers of S. mutans. Using linear mixed-models analysis with difference in numbers of S. mutans from baseline to any time point as the dependent variable, and number of lollipops consumed with effect of time controlled as the predictor variable, participants who consumed more lollipops during the 21-day time period were more likely to have fewer numbers of S. mutans (β = -8.703, p = 0.067). There was a trend toward reduction of S. mutans with consumption of more lollipops during the 21-day period. Recruiting a larger sample for future research may demonstrate a significant reduction.

Evening cortisol is associated with intra-individual instability in daytime napping in nursing home residents with dementia: an allostatic load perspective

BACKGROUND

Circadian rhythm disruption, reflected in alterations in sleep-wake activity and daytime napping behavior, is consistently reported in nursing home (NH) residents with dementia. This disruption may be reflected in day-to-day instability. The concept of allostatic load (AL), a measure of cumulative biological burden over a lifetime, may be a helpful model for understanding cortisol diurnal rhythm and daytime napping activity in this population. The purpose of this study was to examine the association between intra-individual daytime napping episodes and basal cortisol diurnal rhythm in NH residents with dementia in the context of AL.

METHOD

U sing a within-individual longitudinal design (N = 51), the authors observed and recorded daytime napping activity every 20 min for 10 hr per day across 4 consecutive days. The authors obtained saliva samples 4 times each day (upon participants' waking and within 1 hr, 6 hr, and 12 hr of participants' wake time) for cortisol analysis.

RESULTS

The authors categorized participants as high changers (HCs; day-to-day instability in napping activity) or low changers (LCs; day-to-day stability). There were no significant differences in resident characteristics between groups. There was a significant difference between HCs and LCs in napping episodes (F = 4.86, p = .03), with an interaction effect of evening cortisol on napping episodes in the HC group (F = 10.161, p = .001).

CONCLUSIONS

NH residents with unstable day-to-day napping episodes are more responsive to alterations in evening cortisol, an index of a dysregulated hypothalamic-pituitary-adrenal (HPA) axis. They may also be more amenable to environmental intervention, an avenue for further research.

To nap or not to nap: excessive daytime napping is associated with elevated evening cortisol in nursing home residents with dementia

BACKGROUND

Alterations in the sleep-wake cycle, including daytime napping, are consistently reported in persons with dementia (PWD). A dysregulation in the hypothalamic-pituitary-adrenal (HPA) axis, indexed by elevated evening cortisol, may offer one explanation for these alterations. Alternatively, excessive daytime sleeping may alter cortisol rhythm and increase intraindividual variability, potentially contributing to increased environmental reactivity and behavioral symptoms. The purpose of this substudy (N = 12) was to examine the association between daytime napping and basal cortisol diurnal rhythm in nursing home residents with dementia.

METHOD

In this within-individual longitudinal design, saliva samples were obtained daily for 5 consecutive days upon waking and 30-45 min, 6 hr, and 12 hr after waking to obtain a cortisol diurnal rhythm. Behavior and sleep-wake state (nap/no nap) were observed and recorded every 20 min for 12 hr per day for 5 days.

RESULTS

Participants were categorized as high nappers (HNs) or low nappers (LNs). There was a significant difference in evening cortisol levels (t = -2.38, p = .032) and continence (t = 3.37, p = .007) between groups, with HNs exhibiting higher evening cortisol levels. There were no other significant differences in resident characteristics between the two groups.

CONCLUSIONS

These data suggest a link between excessive daytime napping and elevated evening cortisol in PWD consistent with findings in children. Elevated evening cortisol is an indication of a dysregulation in the HPA axis. These preliminary data support a close association between the sleep-wake cycle and HPA-axis regulation in PWD.