Preliminary investigation of interactive associations of sleep and pain with cognition in sedentary middle-aged and older adults.

STUDY OBJECTIVES: The objective of this study was to examine independent and interactive associations between self-reported sleep (sleep efficiency and total sleep time [TST]) and pain with cognition in sedentary middle-aged and older adults. METHODS: Seventy-five sedentary adults at least 50 years of age (Mage = 63.24, standard deviation = 8.87) completed 14 daily diaries measuring sleep and pain. Weekly average sleep efficiency, TST, and pain were computed. Participants also completed computerized cognitive tasks: Letter Series (reasoning), N-back (working memory), Symbol Digit Modalities Test (processing speed, attention), and Number Copy (processing speed). Multiple regression analyses were conducted to determine independent and interactive (with pain) associations of sleep efficiency and TST with cognition, controlling for age, education, and sex. RESULTS: Sleep efficiency and pain interacted in their associations with Letter Series performance and N-back difference scores (2-back minus 1-back). Specifically, higher sleep efficiency was associated with better reasoning and working memory in those with highest pain but not average or lowest pain. TST and pain also interacted in their associations with Letter Series performance. Specifically, longer TST associated with worse reasoning in those with lowest (not average or highest) pain. CONCLUSIONS: Preliminary results show that in sedentary middle-aged and older adults, pain and sleep interact in their associations with executive function tasks. Higher sleep efficiency may be associated with better reasoning and working memory in those with highest pain. Lower TST may be associated with better reasoning in those with lowest pain. Studies evaluating temporal associations between sleep, pain, and cognition are needed.

Anxiety and executive functions in mid-to-late life: the moderating role of sleep.

Objectives: The goal of the study was to examine the influence of sleep efficiency on the relationship between anxiety and executive functions.Method: Secondary data analyses of 82 community-dwelling middle-aged and older adults were performed (M age = 63.00, SD = 8.64). Anxiety was measured using the trait anxiety subscale of the State-Trait Anxiety Inventory. Sleep efficiency was measured using one-week of sleep diary data. Two executive functions, cognitive flexibility and inductive reasoning, were measured using the Trail-Making Test and Letter Series task, respectively. SPSS PROCESS macro software version 2 was used to assess the moderating role of sleep efficiency in the relationship between anxiety and executive functions.Results: Sleep significantly moderated the relationship between anxiety and inductive reasoning. Among middle-aged and older adults with high anxiety, those with good sleep efficiency displayed significantly better inductive reasoning than those with poor sleep efficiency after controlling for age, gender, and education (ΔR2 = .05, p = .017). Sleep efficiency did not significantly moderate the relationship between anxiety and cognitive flexibility.Conclusion: Sleep efficiency weakened the association between anxiety and inductive reasoning in middle-aged and older adults. Evidence from the study suggests better sleep may limit the negative effects of anxiety on executive functions in mid-to-late life. Further research is needed to elucidate the impact of anxiety and sleep on executive functions in clinical populations with anxiety.

Pain inconsistency and sleep in mid to late-life: the role of depression.

Objectives: Inconsistency in pain may lead to depression, which may then influence sleep. Thus, the purpose of this study was to examine whether depression mediates the relationship between day-to-day inconsistency in pain and sleep in middle aged to older adults. Methods: Baseline measures from the Active Adult Mentoring Project were used for secondary data analysis. Participants included 82 adults in mid- to late-life. Pain was assessed for seven consecutive days on an 11-point Likert-scale, with pain inconsistency defined as the seven-day individual standard deviation. A self-report daily diary was used to assess sleep efficiency (SE), total wake time (TWT), total sleep time (TST), and sleep quality (SQ), and depression was assessed using the BDI-II. Results: Mediation analyses revealed that depression partially mediated the relationship between pain inconsistency and SE, TWT, and SQ but not TST. Conclusions: Results indicate that depression may be an important factor through which pain inconsistency influences sleep. Although further research is warranted, these preliminary findings suggest that intervening on both pain inconsistency and depression may be one way to improve sleep in older adults.

Sleep and Pain in Mid- to Late-Life: An Exploration of Day-to-Day Pain Inconsistency.

OBJECTIVES: This study examined how different quantifications of pain (average vs. day-to-day inconsistency) are related to sleep in older adults beyond known predictors. METHODS: Baseline measures from the Active Adult Mentoring Project were used for secondary analyses. Participants included 82 adults in mid- to late-life. Depression was assessed with the BDI-II. Pain intensity was assessed over seven days on a 11-point Likert-scale, while sleep efficiency (SE), total sleep time (TST), and total wake time (TWT) were assessed using a self-report diary. RESULTS: Regression analyses revealed that pain inconsistency was associated with both SE and TWT and accounted for significant variance over age, gender, and depression. In contrast, average pain was not associated with SE, TST, or TWT. CONCLUSIONS: The findings indicate that pain inconsistency may be a more meaningful predictor of sleep disturbance than average pain level, suggesting that one's ability to regulate pain may be related to one's ability to engage in optimal sleep in mid- to late-life. CLINICAL IMPLICATIONS: Pain inconsistency appears to contribute more to sleep disturbance than average pain. Pain inconsistency in late-life warrants greater attention and may be an area of clinical intervention through activity-pacing or coping skills training.

Cardiometabolic disease and features of depression and bipolar disorder: population-based, cross-sectional study.

BACKGROUND: The relative contribution of demographic, lifestyle and medication factors to the association between affective disorders and cardiometabolic diseases is poorly understood. AIMS: To assess the relationship between cardiometabolic disease and features of depresion and bipolar disorder within a large population sample. METHOD: Cross-sectional study of 145 991 UK Biobank participants: multivariate analyses of associations between features of depression or bipolar disorder and five cardiometabolic outcomes, adjusting for confounding factors. RESULTS: There were significant associations between mood disorder features and 'any cardiovascular disease' (depression odds ratio (OR) = 1.15, 95% CI 1.12-1.19; bipolar OR = 1.28, 95% CI 1.14-1.43) and with hypertension (depression OR = 1.15, 95% CI 1.13-1.18; bipolar OR = 1.26, 95% CI 1.12-1.42). Individuals with features of mood disorder taking psychotropic medication were significantly more likely than controls not on psychotropics to report myocardial infarction (depression OR = 1.47, 95% CI 1.24-1.73; bipolar OR = 2.23, 95% CI 1.53-3.57) and stroke (depression OR = 2.46, 95% CI 2.10-2.80; bipolar OR = 2.31, 95% CI 1.39-3.85). CONCLUSIONS: Associations between features of depression or bipolar disorder and cardiovascular disease outcomes were statistically independent of demographic, lifestyle and medication confounders. Psychotropic medication may also be a risk factor for cardiometabolic disease in individuals without a clear history of mood disorder.

Refining a Prostate Cancer Survivor's Toolkit.

Men who have undergone radical prostatectomy for the treatment of prostate cancer often lack knowledge about post-surgical care to bridge this gap in knowledge. Thus, we developed, refined, and validated a prostate cancer survivor's toolkit, which provides these men in the care required after this procedure.

Development and Psychometric Evaluation of the Chinese Feeding Difficulty Index (Ch-FDI) for People with Dementia.

AIMS: To develop and evaluate the psychometric properties of a Chinese Feeding Difficulty Index (Ch-FDI) which assesses feeding difficulties in people with dementia (PwD). RESEARCH DESIGN AND METHOD: Scale items were developed using literature review based on Model of Feeding Difficulty. Content validity was evaluated and items were modified by expert panel. Following translation and back-translation, the Ch-FDI was piloted on residents with dementia. The reliability was tested by inter-rater reliability and test-retest reliability. Internal reliability was established by calculating Cronbach's α coefficient. The concurrent validity was evaluated by correlating with similar scale, the Edinburgh Feeding Evaluation in Dementia (EdFED). The exploratory factor analysis (EFA) with varimax rotation and parallel analysis (PA) was performed to test construct validity. METHOD: Participants were recruited from long-term care facilities in Taiwan. A total of 213 residents with dementia participated in this study during May, 2010 to February, 2011. RESULTS: Content validation, translation and psychometric testing were completed on the 19 items of the Ch-FDI. The translated scale was piloted on 213 residents with dementia of feeding difficulty who were recruited from eight long-term care facilities in Taiwan. The reliability was supported by the internal consistency of Cronbach's α of 0.68 and a test-retest coefficient of 0.85. The content validity, face validity, concurrent validity, and construct validity were used. CONCLUSIONS: The Ch-FDI is a newly developed scale with fair psychometric properties aimed to measure feeding difficulties among residents with dementia in long-term care facilities in Taiwan. Using this reliable and valid tool can help healthcare providers to assess feeding problems of PwD and provide feeding assistance in order to promote quality of care during mealtime in long-term care facilities.

Intervention markers of physical activity maintenance in older adults.

OBJECTIVES: To identify intervention components that may promote longterm changes of physical activity among older adults in a behavioral theory-based physical activity trial. METHODS: Participants (N = 24; aged 65 ± 8.79 years) shared perceptions of intervention components at the end of the intervention and physical activity was assessed at 18 months. Mixed-methods analyses using a pragmatic content analysis of interview data were conducted. RESULTS: Active study participants (25%) cited more specific goals/actions to achieve goals and more social support from family/friends, and had significantly higher self-determined motivation mean scores at 18 months than insufficiently active study participants (75%). CONCLUSIONS: Specific goal-setting behaviors and social support from family/friends may be key elements of physical activity maintenance in older adults.

Chronic multisite pain in major depression and bipolar disorder: cross-sectional study of 149,611 participants in UK Biobank.

BACKGROUND: Chronic pain has a strong association with major depressive disorder (MDD), but there is a relative paucity of studies on the association between chronic multisite pain and bipolar disorder (BD). Such studies are required to help elucidate the complex biological and psychological overlap between pain and mood disorders. The aim of this study is to investigate the relationship between chronic multisite pain and mood disorder across the unipolar-bipolar spectrum. METHODS: We conducted a cross-sectional study of 149,611 UK Biobank participants. Self-reported depressive and bipolar features were used to categorise participants into MDD and BD groups and a non-mood disordered comparison group. Multinomial logistic regression was used to establish whether there was an association between extent of chronic pain (independent variable) and mood disorder category (dependent variable), using no pain as the referent category, and adjusting for a wide range of potential sociodemographic, lifestyle and comorbidity confounders. RESULTS: Multisite pain was significantly more prevalent in participants with BD and MDD, for example, 4-7 pain sites: BD 5.8%, MDD 4.5%, and comparison group 1.8% (p < 0.001). A relationship was observed between extent of chronic pain and risk of BD and persisted after adjusting for confounders (relative to individuals with no chronic pain): 2-3 sites RRR of BD 1.84 (95% CI 1.61, 2.11); 4-7 sites RRR of BD 2.39 (95% CI 1.88, 3.03) and widespread pain RRR of BD 2.37 (95% CI 1.73, 3.23). A similar relationship was observed between chronic pain and MDD: 2-3 sites RRR of MDD 1.59 (95% CI 1.54, 1.65); 4-7 sites RRR of MDD 2.13 (95% CI 1.98, 2.30); widespread pain RRR of MDD 1.86 (95% CI 1.66, 2.08). CONCLUSIONS: Individuals who report chronic pain and multiple sites of pain are more likely to have MDD and are at higher risk of BD. These findings highlight an important aspect of comorbidity in MDD and BD and may have implications for understanding the shared neurobiology of chronic pain and mood disorders.

Using posturography to measure balance control during seated tai chi.

BACKGROUND: Tai Chi for Arthritis (TCA) is recognized by the CDC as an evidenced-based program to prevent falls in older adults. Although seated Tai Chi is recommended for those unable to stand, little is known about balance control during seated TCA. PURPOSE: To explore the use of posturography to assess differences between experts and non-expert practitioners of seated TCA. METHODS: Twenty-three participants were recruited from those attending a Tai cChi workshop. While seated in a hard back chair centered on a force platform, participants performed selected forms from TCA and then did them in a continuous sequence. Center of pressure (CoP) indices to assess balance were normalized by height and then compared between expert and non-expert participants. RESULTS: Experts had significantly greater average velocity and path length (p = 0.02) for the entire sequence and open/close, but not for CoP 95% Confidence ellipse area. No significant differences in the CoP were found for commencement, wave hands, or single whip. CONCLUSIONS: A few differences in balance control while performing seated TCA movements were found. Future studies are needed to determine whether these can be accounted for by quality of the Tai Chi movements or factors associated with the seated position.

The role of resilience and social support in predicting postdeployment adjustment in otherwise healthy Navy personnel.

The purpose of this study was to determine if resilience, social support, and exposure to combat, stressful deployment environments, and additional stressful life events predicted short-term (12 months or less) postdeployment adjustment in a relatively healthy subset of Navy service members. One hundred and thirty-two service members between 3 and 6 months postdeployment completed anonymous surveys at a deployment health center. Service members with probable post-traumatic stress disorder and those who were at risk for harm to self or others were excluded. There was relatively low variance in exposure to combat, stressful deployment environments, and additional stressful life events for this convenience sample. Although the sample was a relatively healthy subset of service members and conclusions may not be generalizable to larger populations, 56% endorsed considerable adjustment difficulties. Results of logistic regression indicated that greater resilience, greater postdeployment social support, and less stressful deployment environments predicted greater postdeployment adjustment. Resilience and postdeployment social support remained significant predictors of postdeployment adjustment when controlling for covariates. Results also suggest that individual augmentee experience may be a protective factor against postdeployment adjustment difficulties-at least in otherwise healthy service members.

Tai chi intervention improves dynamic postural control during gait initiation in older adults: a pilot study.

Tai Chi intervention has been shown to be beneficial for balance improvement. The current study examined the effectiveness of Tai Chi to improve the dynamic postural control among older adults with mobility disability. Six sedentary older adults with mobility disability participated in a 16-week Tai Chi intervention consisting of one hour sessions three times a week. Dynamic postural control was assessed pre- and post intervention as participants initiated gait in four stepping conditions: forward; 45° medially, with the stepping leg crossing over the other leg; 45° and 90° laterally. The center of pressure (CoP) displacement, velocity, and its maximum separation distance from the center of mass in the anteroposterior, mediolateral, and resultant directions were analyzed. Results showed that in the postural phase, Tai Chi increased the CoP mediolateral excursions in the medial (13%) and forward (28%) conditions, and resultant CoP center of mass distance in the medial (9%) and forward (19%) conditions. In the locomotion phase, the CoP mediolateral displacement and velocity significantly increased after the Tai Chi intervention (both by > 100% in the two lateral conditions). These results suggest that through alteration in CoP movement characteristics, Tai Chi intervention might improve the dynamic postural control during gait initiation among older adults.

Gender differences in the association between adiposity and probable major depression: a cross-sectional study of 140,564 UK Biobank participants.

BACKGROUND: Previous studies on the association between adiposity and mood disorder have produced contradictory results, and few have used measurements other than body mass index (BMI). We examined the association between probable major depression and several measurements of adiposity: BMI, waist circumference (WC), waist-hip-ratio (WHR), and body fat percentage (BF%). METHODS: We conducted a cross-sectional study using baseline data on the sub-group of UK Biobank participants who were assessed for mood disorder. Multivariate logistic regression models were used, adjusting for potential confounders including: demographic and life-style factors, comorbidity and psychotropic medication. RESULTS: Of the 140,564 eligible participants, evidence of probable major depression was reported by 30,145 (21.5%). The fully adjusted odds ratios (OR) for obese participants were 1.16 (95% confidence interval (CI) 1.12, 1.20) using BMI, 1.15 (95% CI 1.11, 1.19) using WC, 1.09 (95% CI 1.05, 1.13) using WHR and 1.18 (95% CI 1.12, 1.25) using BF% (all p < 0.001). There was a significant interaction between adiposity and gender (p = 0.001). Overweight women were at increased risk of depression with a dose response relationship across the overweight (25.0-29.9 kg/m2), obese I (30.0-34.9 kg/m2), II (35.0-39.9 kg/m2) and III (≥40.0 kg/m2) categories; fully adjusted ORs 1.14, 1.20, 1.29 and 1.48, respectively (all p < 0.001). In contrast, only obese III men had significantly increased risk of depression (OR 1.29, 95% CI 1.08, 1.54, p = 0.006). CONCLUSION: Adiposity was associated with probable major depression, irrespective of the measurement used. The association was stronger in women than men. Physicians managing overweight and obese women should be alert to this increased risk.

Reaction time and incident cancer: 25 years of follow-up of study members in the UK Health and Lifestyle Survey.

OBJECTIVES: To investigate the association of reaction time with cancer incidence. METHODS: 6900 individuals aged 18 to 94 years who participated in the UK Health and Lifestyle Survey in 1984/1985 and were followed for a cancer registration for 25 years. RESULTS: Disease surveillance gave rise to 1015 cancer events from all sites. In general, there was essentially no clear pattern of association for either simple or choice reaction time with cancer of all sites combined, nor specific malignancies. However, selected associations were found for lung cancer, colorectal cancer and skin cancer. CONCLUSIONS: In the present study, reaction time and its components were not generally related to cancer risk.

Heaviness, health and happiness: a cross-sectional study of 163066 UK Biobank participants.

BACKGROUND: Obesity is known to increase the risk of many diseases and reduce overall quality of life. This study examines the relationship with self-reported health (SRH) and happiness. METHODS: We conducted a cross-sectional study of the 163 066 UK Biobank participants who completed the happiness rating. The association between adiposity and SRH and happiness was examined using logistic regression. SRH was defined as good (excellent, good), or poor (fair, poor). Self-reported happiness was defined as happy (extremely, very, moderately) or unhappy (moderately, very, extremely). RESULTS: Poor health was reported by 44 457 (27.3%) participants. The adjusted ORs for poor health were 3.86, 2.92, 2.60 and 6.41 for the highest, compared with lowest, deciles of Body Mass Index, waist circumference, waist to hip ratio and body fat percent, respectively. The associations were stronger in men (p<0.001). Overall, 7511 (4.6%) participants felt unhappy, and only class III obese participants were more likely to feel unhappy (adjusted OR 1.33, 95% CI 1.15 to 1.53, p<0.001) but the associations differed by sex (p<0.001). Among women, there was a significant association between unhappiness and all levels of obesity. By contrast, only class III obese men had significantly increased risk and overweight and class I obese men were less likely to be unhappy. CONCLUSIONS: Obesity impacts adversely on happiness as well as health, but the association with unhappiness disappeared after adjustment for self-reported health, indicating this may be mediated by health. Compared with obese men, obese women are less likely to report poor health, but more likely to feel unhappy.

Exercise and sleep in community-dwelling older adults: evidence for a reciprocal relationship.

Exercise behaviour and sleep are both important health indicators that demonstrate significant decreases with age, and remain modifiable well into later life. The current investigation examined both the chronic and acute relationships between exercise behaviour and self-reported sleep in older adults through a secondary analysis of a clinical trial of a lifestyle intervention. Seventy-nine community-dwelling, initially sedentary, older adults (mean age = 63.58 years, SD = 8.66 years) completed daily home-based assessments of exercise behaviour and sleep using daily diary methodology. Assessments were collected weekly and continued for 18 consecutive weeks. Multilevel models revealed a small positive chronic (between-person mean-level) association between exercise and wake time after sleep onset, and a small positive acute (within-person, day-to-day) association between exercise and general sleep quality rating. The within-person exercise and general sleep quality rating relationship was found to be reciprocal (i.e. sleep quality also predicted subsequent exercise behaviour). As such, it appears exercise and sleep are dynamically related in older adults. Efforts to intervene on either sleep or exercise in late-life would be wise to take the other into account. Light exposure, temperature regulation and mood may be potential mechanisms of action through which exercise can impact sleep in older adults.

Cognitive Inconsistency and Practice-Related Learning in Older Adults.

The current study examined predictors of individual differences in the magnitude of practice-related improvements achieved by 87 older adults (meanage 63.52 years) over 18-weeks of cognitive practice. Cognitive inconsistency in both baseline trial-to-trial reaction times and week-to-week accuracy scores was included as predictors of practice-related gains in two measures of processing speed. Conditional growth models revealed that both reaction time and accuracy level and rate-of-change in functioning were related to inconsistency, even after controlling for mean-level, but that increased inconsistency was negatively associated with accuracy versus positively associated with reaction time improvement. Cognitive inconsistency may signal dysregulation in the ability to control cognitive performance or may be indicative of adaptive attempts at functioning.

Prevalence and characteristics of probable major depression and bipolar disorder within UK biobank: cross-sectional study of 172,751 participants.

OBJECTIVES: UK Biobank is a landmark cohort of over 500,000 participants which will be used to investigate genetic and non-genetic risk factors for a wide range of adverse health outcomes. This is the first study to systematically assess the prevalence and validity of proposed criteria for probable mood disorders within the cohort (major depression and bipolar disorder). METHODS: This was a descriptive epidemiological study of 172,751 individuals assessed for a lifetime history of mood disorder in relation to a range of demographic, social, lifestyle, personality and health-related factors. The main outcomes were prevalence of a probable lifetime (single) episode of major depression, probable recurrent major depressive disorder (moderate), probable recurrent major depressive disorder (severe), probable bipolar disorder and no history of mood disorder (comparison group). Outcomes were compared on age, gender, ethnicity, socioeconomic status, educational attainment, functioning, self-reported health status, current depressive symptoms, neuroticism score, smoking status and alcohol use. RESULTS: Prevalence rates for probable single lifetime episode of major depression (6.4%), probable recurrent major depression (moderate) (12.2%), probable recurrent major depression (severe) (7.2%) and probable bipolar disorder (1.3%) were comparable to those found in other population studies. The proposed diagnostic criteria have promising validity, with a gradient in evidence from no mood disorder through major depression and probable bipolar disorder in terms of gender distribution, socioeconomic status, self-reported health rating, current depressive symptoms and smoking. SIGNIFICANCE: The validity of our proposed criteria for probable major depression and probable bipolar disorder within this cohort are supported by these cross-sectional analyses. Our findings are likely to prove useful as a framework for a wide range of future genetic and non-genetic studies.

IQ in childhood and atherosclerosis in middle-age: 40 Year follow-up of the Newcastle Thousand Families Cohort Study.

OBJECTIVE: Carotid intima-media thickness (IMT) is a known precursor to coronary heart disease (CHD) and other relevant health outcomes such as stroke and cognitive impairment. In addition, higher childhood intelligence has been associated with lower risk of coronary heart disease events in later life, although the mechanisms of effect are unclear. We therefore examined the association between childhood intelligence and atherosclerosis using carotid IMT as a marker of the atherosclerotic process. APPROACH: Participants were 412 members of the Newcastle Thousand Families Study, a prospective cohort study of all 1142 births in the city of Newcastle in May and June 1947, who took an IQ test and English and arithmetic tests at age 11 years. Study members participated in a medical examination and lifestyle assessment at age 49-51 years during which IMT was measured using ultrasound techniques. RESULTS: Individuals with higher childhood IQ score had a lower mean IMT in middle-age. A standard deviation higher score in childhood overall IQ was associated with a 0.053 mm (95% CI -0.102, -0.004) lower IMT in men and a 0.039 mm (95% CI -0.080, -0.002) lower IMT in women. Similar levels of association were found for the English and arithmetic tests. After adjustment for a range of covariates including education, the size of effect was undiminished in men but increased in women. CONCLUSIONS: In the present study, higher childhood IQ scores were associated with a lower degree of atherosclerosis by middle-age.

Exploring behavioral markers of long-term physical activity maintenance: a case study of system identification modeling within a behavioral intervention.

Efficacious interventions to promote long-term maintenance of physical activity are not well understood. Engineers have developed methods to create dynamical system models for modeling idiographic (i.e., within-person) relationships within systems. In behavioral research, dynamical systems modeling may assist in decomposing intervention effects and identifying key behavioral patterns that may foster behavioral maintenance. The Active Adult Mentoring Program was a 16-week randomized controlled trial of a group-based, peer-delivered physical activity intervention targeting older adults. Time-intensive (i.e., daily) physical activity reports were collected throughout the intervention. We explored differential patterns of behavior among participants who received the active intervention (N = 34; 88% women, 64.1 ± 8.3 years of age) and either maintained 150 minutes/week of moderate to vigorous intensity physical activity (MVPA; n = 10) or did not (n = 24) at 18 months following the intervention period. We used dynamical systems modeling to explore whether key intervention components (i.e., self-monitoring, access to an exercise facility, behavioral initiation training, behavioral maintenance training) and theoretically plausible behavioral covariates (i.e., indoor vs. outdoor activity) predicted differential patterns of behavior among maintainers and nonmaintainers. We found that maintainers took longer to reach a steady-state of MVPA. At week 10 of the intervention, nonmaintainers began to drop whereas maintainers increased MVPA. Self-monitoring, behavioral initiation training, percentage of outdoor activity, and behavioral maintenance training, but not access to an exercise facility, were key variables that explained patterns of change among maintainers. Future studies should be conducted to systematically explore these concepts within a priori idiographic (i.e., N-of-1) experimental designs.