Sleep

Eight studies assessed relations between PD features and sleep. Of these, one examined group differences sleep patterns between patients with sleep conditions and patients with BPD, one assessed sleep patients for the presence of PDs, five assessed sleep difficulties in patients with PDs, and one used an epidemiological sample.

PDs were relatively common among patients suffering from sleep disorders (Ruiter, Lichstein, Nau, & Geyer, 2012). Specifically, in a sample of adults with chronic insomnia and hypnotic dependence (N = 84), PD features were assessed with the SCID-II screening questionnaire. The most prevalent PDs in this sample were Cluster C PDs, constituting nearly half of the sample (50%). In terms of specific PDs, the most common was obsessive compulsive (46%), followed by avoidant (12%), paranoid, narcissistic PDs, and BPD (11% each). Both obsessive compulsive and avoidant PD features were associated with more influence of insomnia on daytime functioning. Of note, the SCID-II screening questionnaire is an instrument with yes/no questions rather than a comprehensive diagnostic tool, designed to facilitate the more efficient completion of the structured clinical interview for PDs, in which interviewers query only those items rated “yes” on the screening questionnaire. Although these findings suggest high rates of PDs in patients with sleep problems, research in this area is at a preliminary stage.

Five studies have investigated sleep problems among individuals with BPD (Asaad, Okasha, & Okasha, 2002; Bastien, Guimond, St-Jean, & Lemelin, 2008; Plante, Frankenburg, Fitzmaurice, & Zanarini, 2013b; Semiz, Basoglu, Ebrinc, & Cetin, 2008). Compared to age- and sex-matched participants without psychopathology (n = 100), BPD patients (n = 88) reported worse subjective sleep quality (Semiz et al., 2008). Indeed, the vast majority (95.5%) of BPD patients described themselves as poor sleepers, compared to only 12% of the control group. Furthermore, BPD patients reported higher self-reported dream anxiety (e.g., nightmares, autonomic hyperactivity, and difficulty falling asleep) than the control group, and within the BPD sample, those who had nightmare disorder were more clinically severe (e.g., child abuse history, unemployment, self-harm, and lower education) than BPD patients without a nightmare disorder. In research using subjective and objective measures to compare BPD patients (n = 20) to a clinical control group of depressed patients (n = 20), however, BPD patients evidenced comparable, and on some indices slightly better, sleep patterns than the clinical controls (Asaad et al., 2002). In fact, the depressed participants (n = 20) evidenced significantly longer sleep latency, lower sleep efficiency, higher number of nighttime awakenings, shorter REM latency and higher REM density than BPD participants. Also drawing on subjective (daily monitoring and questionnaires) and objective measures of sleep, researchers compared BPD patients (n = 12) to patients with insomnia (n = 30) and self-reported good sleepers without insomnia (n = 15; (Bastien et al., 2008). Patients with BPD reported comparable sleep disturbance, and also evidenced similar levels of sleep onset latency, sleep time and sleep efficiency in the laboratory relative to individuals with insomnia. These groups diverged with respect to stage four sleep, however, with BPD patients evidencing a greater proportion and amount of time in this stage of sleep than paradoxical insomniacs. In a study based on epidemiological data (from the NCS-R; N = 5692) BPD symptoms were significantly associated with self-reported difficulty initiating sleep, difficulty maintaining sleep, and waking earlier than desired, as well as negative consequences of poor sleep (Selby, 2013). These sleep problems were similar to those reported by individuals with Axis I disorders (Selby, 2013). Using 16-year longitudinal follow-up data from the MSAD, recovered BPD patients (n = 105) reported shorter sleep onset latency, less fatigue-related dysfunction (Plante, Frankenburg, Fitzmaurice, & Zanarini, 2013a), and less severe maladaptive sleep related cognitions relative to non-recovered (n = 118) BPD patients (Plante et al., 2013b). These data suggest that as BPD symptoms improve, sleep problems may also improve.

Preliminary research also points to sleep disturbance in other PDs. Among 110 forensic psychiatric patients, most of whom (83%) had a PD (60% antisocial, 27% BPD, 28% narcissistic PD), 29% a self-reported sleep disorder (Kamphuis, Karsten, de Weerd, & Lancel, 2013a). Thus, the prevalence of sleep disorders in PD samples may exceed that of sleep disorders (i.e., insomnia) in other populations, with rates from 6–10% (Roth, 2007). In addition, 49% of those with PDs exceeded clinical cut offs for poor sleep quality on self-report measures. Antisocial PD was the only disorder that significantly predicted self-reported poor sleep quality.

Overall, these findings suggest that sleep impairments are relatively common among those with BPD and possibly antisocial PD. Nevertheless, these impairments are comparable to those associated with other psychopathology or sleep disorders. The research on sleep disturbance in BPD included subjective and objective indices, as well as clinical comparison groups. Given preliminary evidence suggesting that Cluster C PDs may be overrepresented among those suffering from sleep disorders, further research should conduct comprehensive assessments for PDs in order to compare rates of sleep disorders across diverse PDs.

Obesity

Seventeen studies investigated the relation between PDs and obesity via a number of methods (e.g., self-report and laboratory measures) as well as across a variety of samples (e.g., clinical, epidemiological, community). Specifically, nine studies used clinical patient samples, five studies used epidemiological data (n = 4 NCS/NCS-R, n = 1 Saint Louis) and three studies used longitudinal community-based samples (n = 2 MSAD, n = 1 Children in the Community [CIC]). Within studies examining clinical patient samples, four of the eight used samples of patients who were candidates for bariatric surgery. Overall, studies support a positive association between obesity and the presence of and/or symptoms of PDs.

Four studies investigated rates of PD among patients seeking or referred for bariatric surgery (Black, Goldstein, & Mason, 2003; Lier, Biringer, Stubhaug, Eriksen, & Tangen, 2011; Mauri et al., 2008; Sansone, Schumacher, Wiederman, & Routsong-Weichers, 2008). A substantial proportion (19.5–56%) of patients in these studies evidenced PD symptoms or diagnoses well above the rates of PDs typically seen in the general population. For example, the prevalence of PDs (diagnosed via structured clinical interviews) among consecutively admitted obese (BMI ≥ 30 kg/m2) candidates for bariatric surgery (n = 282; 79.8% female) was 19.5% (Mauri et al., 2008). Of these, nearly all of the PDs detected were Cluster C disorders (avoidant, dependent, and obsessive compulsive, n = 53). Similarly, avoidant was the most common PD in a different sample (n = 141) of obese bariatric surgery patients (Lier et al., 2011). In a smaller patient sample (n = 44), Cluster A disorders (49%) were the most prevalent PD (Black et al., 2003). Thus, although the rates of PD are relatively high among obese patients seeking surgery, there appears to be some discrepancy regarding the most prevalent types of PD.

Five additional studies investigated symptoms of PD in patient samples not seeking bariatric surgery (Carpiniello et al., 2009; Sansone, Hahn, Dittoe, & Wiederman, 2012; Sansone, Wiederman, Sansone, & Monteith, 2001; van Hanswijck de Jonge, van Furth, Lacey, & Waller, 2003). Rates of PD in these samples ranged from 8–65%. For example, among patients undergoing cardiac stress testing (n = 238), 8% scored above BPD clinical cut off on a self-report measure (Sansone et al., 2012). Among obesity treatment centre patients (n = 150), 31% of female and 19% of male patients had a PD based on a clinical interview (Carpiniello et al., 2009). Similarly, overweight patients with binge eating disorder (N = 75) in a trial of self-help interventions demonstrated high rates of PDs, with nearly one-fourth (24%) meeting criteria for a PD (Masheb & Grilo, 2008). The most common PDs in this sample were Cluster C. Furthermore, PD presence predicted negative affect and eating disorder symptoms post-treatment.

Evidence also supports an association between PDs and obesity. Drawing from the NESARC study, four papers examined obesity and PD (Goldstein et al., 2008; Mather, Cox, Enns, & Sareen, 2008; Petry, Barry, Pietrzak, & Wagner, 2008; Pickering, Grant, Chou, & Compton, 2007). Results revealed that antisocial (OR = 1.03), avoidant (OR = 1.04), obsessive compulsive (OR = 1.02), paranoid (OR = 1.03), and schizoid (OR = 1.03) PDs were associated with heightened BMI (e.g., obesity or extreme obesity), whereas depressive and histrionic PD were not, ORs = 1.03 and 1.01, respectively (Petry et al., 2008). BPD was not assessed in this sample. In a different analysis however, after adjusting for demographic and physical health variables, PDs were not associated with BMI in men (Pickering et al., 2007). Among women, avoidant PD was associated with higher likelihood of being in the extremely obese category (OR = 1.7), and among women, antisocial PD was associated with higher likelihood of being classified as overweight (OR = 1.5) or extremely obese (OR = 1.9). In another study, controlling for Axis I diagnoses and other relevant demographic variables, obese individuals had higher odds of meeting criteria for at least one Cluster A PD (Mather et al., 2008). Extremely obese individuals had higher odds of having at least one Cluster B PD, such as antisocial and avoidant PD. Whereas overweight men were less likely to meet criteria for multiple PDs, overweight women were more likely to meet criteria for antisocial or multiple PDs. In this data set, 3.7% of the sample met criteria for antisocial PD (Goldstein et al., 2008). The relation of antisocial PD and obesity or extreme obesity among women remained (ORs = 1.4–3.2), even after controlling for relevant demographic factors, substance use and medical conditions. In another sample of 1064 community participants in Saint Louis, higher BMI was associated with greater BPD severity, as assessed by a clinical interview (Iacovino, Powers, & Oltmanns, 2014).

Longitudinal studies have suggested an association of PDs with later obesity. In the MSAD studies, of the 264 patients with BPD at the 6-year follow-up assessment, 74 (28%) patients were obese, whereas at baseline, only 46 (17%) patients had been obese (Frankenburg & Zanarini, 2006b), although it is unclear how these compare to rates seen in the general population. A subset of these patients (N = 210) completed the 10-year follow-up (Frankenburg & Zanarini, 2011a) and, among these participants, BMI was associated with BPD symptoms (self-mutilation; z = 2.62; suicide attempts; z = 1.86) at baseline, and predicted poorer psychosocial outcomes across time. Each 5-unit increase in BMI was associated with a greater likelihood of multiple weight-related medical conditions (z = 5.48; 60%), visiting the emergency room (z = 8.68; 27%), or being hospitalized for medical reasons (z = 4.46; 35%). Similarly, in another longitudinal project of 658 community participants (Johnson, Cohen, Kasen, & Brook, 2006a), the prevalence of any PD ranged from 10.1%-14.7%. Furthermore, the presence of a PD by early adulthood predicted greater risk for binge eating, dietary restriction, obesity, and eating disorders at age 33. Further, specific PDs demonstrated unique associations with health-related behaviour problems. Controlling for demographics, several PDs predicted eating disorders (BPD, histrionic, schizoid PDs), binge eating (antisocial, BPD, dependent, depressive, histrionic, passive aggressive, schizotypal PDs), obesity (antisocial, schizoid, schizotypal PDs), purging (BPD, histrionic, schizotypal PDs) and restricting behaviours (depressive PD).

This set of findings indicates that there are high rates of PD among obese individuals seeking bariatric surgery and those not seeking surgery, suggesting that obesity and PDs tend to co-occur. In large-scale epidemiological or longitudinal community samples, there appear to be concurrent relations between several PDs and obesity, as well as evidence suggesting that PDs prospectively predict greater obesity and the onset of eating problems, including binge eating.

Chronic Pain/Headaches

Twenty-two studies investigated the relation between PDs and chronic pain. Chronic pain included self-reported pain intensity, interference, and self-reported or provider-identified pain conditions such as headache, back pain or arthritis. Five studies assessed relations between headache and PDs, whereas 17 studies looked at chronic pain generally. Fifteen studies examined PD prevalence in pain patient samples, 3 studies used psychiatric patient samples, and 4 studies examined PD-pain associations using epidemiological data. Four studies used chart review, and one study compared patients pre- and post-treatment.

Data from epidemiological studies broadly suggest a positive relation between chronic pain and PDs. Drawing from the NCS-R part II (N = 5692), individuals with versus without chronic pain were more likely to screen positive using the IPDE for antisocial and/or BPD traits (Braden & Sullivan, 2008). This pattern did not emerge, however, when examining specific pain issues involving chronic back and neck problems. Also from the NCS-R sample, findings revealed that a history of self-reported pain conditions (arthritis, headaches, spinal pain, other) predicted higher levels of BPD symptoms specifically, even after controlling for relevant demographic variables and symptoms of psychopathology (McWilliams & Higgins, 2013). Population-based studies in Norway compared individuals (n = 369) with any positive endorsement on the Iowa Personality Disorder Screen (IPDS; a short form containing five items, each corresponding to a PD), to age- and gender-matched controls (n = 1845) who endorsed no items on this measure (Olssøn & Dahl, 2009). Results suggest that participants that endorsed PD items were more likely to rate their health poorly (18% vs. 9%), suffer from fibromyalgia (4% vs. 2%), suffer from recent musculoskeletal pain (33% vs. 22%), and report dissatisfaction with their last visit to their general practitioner (57% vs. 44%). In other work using the same sample, individuals endorsing the avoidant PD item on the IPDS (n = 280), compared with those who did not, were more likely to rate their health poorly (50% vs. 16%), suffer from a somatic condition (30% vs. 19%), have impairing musculoskeletal pain (37% vs. 20%), and frequent visits to a general practitioner (36% vs. 15%; Olssøn & Dahl, 2012). The large, nationally-representative nature of the samples used in these studies is a strength; however, the restricted assessment of PDs or lack of comparison across PDs limits our ability to draw conclusions about specific associations between or among PDs in conferring risk for pain conditions.

Studies using clinical pain patient samples (n = 13) yielded similar findings to the epidemiological studies. Patients with chronic back pain (Breckenridge & Clark, 2003), jaw pain/facial discomfort (Wright et al., 2004), headaches (Atasoy, Atasoy, Unal, Emre, & Sumer, 2005; Loder & Geweke, 2002; Rothrock et al., 2007) and other chronic pain conditions (Conrad et al., 2007; Egloff, Maecker, Stauber, Sabbioni, Tunklova, & von Känel, 2012; Fischer-Kern et al., 2011; Fishbain et al., 2007; Proctor, Estroff, Empting, Shearer-Williams, & Hoffmann, 2013; Sansone, Whitecar, Meier, & Murry, 2001; Sansone, Whitecar, & Wiederman, 2009; Tragesser, Bruns, & Disorbio, 2010; Wilsey et al., 2008) evidenced high rates of PDs or PD features (13–28%), particularly when compared to rates in the general population (approximately 10%; (Samuels, 2011). The methods used to assess PD symptoms was highly variable across these studies, ranging from structured diagnostic interviews to self-reported symptoms, with some studies relying on assessments of specific PDs and others assessing multiple PDs.

In psychiatric samples, PDs were associated with chronic pain. Among depressed geriatric psychiatric inpatients (n = 148), 13% of those with chronic pain (n = 92) versus 0% without chronic pain (n = 56) had a PD documented in their medical chart (Meeks et al., 2008). In addition, symptoms of migraine were assessed among first-degree relatives of individuals with obsessive compulsive disorder (n = 168) and healthy controls (n = 184; Manlick, Black, Stumpf, McCormick, & Allen, 2012). The odds of meeting criteria for at least one PD on a structured diagnostic interview were significantly higher (OR = 3.31) among those with migraines (Manlick et al., 2012). When examining specific PDs, migraines were associated with paranoid PD (OR = 3.18) and mixed PDs (OR = 5), although other PDs were not assessed.

Research has identified an association between BPD and chronic pain. For instance, studies have found that BPD symptoms are correlated with migraine headaches (Sansone et al., 2009), somatic preoccupation among pain patients (Sansone, Whitecar, et al., 2001), and are highly prevalent (20%) in medical outpatients (n = 87; Sansone, Pole, Dakroub, & Butler, 2006). Furthermore, among migraine patients (n = 100), BPD diagnoses (derived via chart review and self-report) were associated with migraine severity and disability; BPD participants (n = 50) reported three-fold greater functional incapacity due to migraine symptoms (self-reported as ‘disabling’) compared to migraine sufferers without BPD (Rothrock et al., 2007). Nevertheless, these studies did not assess multiple PDs, so it is not possible to determine whether BPD specifically or PDs more generally, are uniquely associated with pain and related impairment.

There appears to be some support for obsessive compulsive PD being uniquely related to chronic pain. One study found that obsessive compulsive PD (28%) and BPD (26%) were the most commonly diagnosed PDs in a sample of chronic pain (n = 43) patients (Fischer-Kern et al., 2011). In a larger sample of chronic pain patients (n = 216), 62.5% met criteria for obsessive compulsive PD based on a structured interview, whereas only 5% met criteria for other PDs (Proctor et al., 2013). Likewise, among patients with medication overuse headaches, those that also had pre-existing migraines (n = 50; vs. episodic tension headaches, n = 31) had higher rates of obsessive compulsive PD diagnosed via structured clinical interviews (Atasoy et al., 2005). Among jaw pain patients (n = 43), Cluster C PDs generally, and obsessive compulsive PD specifically, conferred higher risk for pain to persist and become chronic (Wright et al., 2004).

Beyond conferring risk for pain conditions, PDs may be associated with higher rates of service utilization among pain patients (e.g. Olsson & Dahl, 2012). In one study, authors tracked calls to a headache practitioner’s office over one month (Loder & Geweke, 2002). Of the 165 calls from 90 callers, most callers (n = 77) had a PD documented in their chart, 91% of repeat callers had a PD, and all 11 emergency calls came from an individual with a PD. The authors suggest that patients with PDs place a disproportionate burden on telephone practice as 24 ½ hours of staff time went toward answering those calls during the month. Migraine sufferers with BPD (n = 50) also had more unscheduled visits for acute headache treatment over the treatment period (an average of 3.1 visits vs. < 1 in non-PD migraine patients; Rothrock et al., 2007). Conversely, in a study of Swedish chronic pain patents (n = 184), depression (OR = 2.60), but not PDs (OR = 0.57) were found to be a significant predictor of disability status across one year (Ericsson et al., 2002). The results from this study suggest that examining the co-occurrence of PDs with other psychiatric disorders may be crucial in aiding our understanding of what may be unique in the relations between pain and PD above and beyond other disorders.

Taken together, these results suggest that individuals with chronic pain have high rates of PDs, those with chronic pain and PD have high rates of service utilization, and that pain conditions and PDs tend to co-occur in the general population.

Chronic Health Conditions

Seventeen studies investigated the relation between PD and chronic health conditions. Chronic health conditions were assessed by self-report and providers. Eight studies used clinical patient samples, four studies used epidemiological data (two of which were described in the Chronic Pain Section) and four studies used longitudinal community-based samples. Three of these four longitudinal community based studies used the same sample (MSAD). Overall, studies support a positive relation between chronic health conditions and PDs.

PD symptoms are prevalent among patients with a variety of chronic health conditions. In particular, PDs were prevalent in samples of 61 liver transplant patients (18%; Gish et al., 2001), patients (n = 18) with multiple chemical sensitivities (39%; Black, Okiishi, & Schlosser, 2001), patients (n = 64) with HIV-seropositive status (11–36%; Marquine et al., 2014), and patients (n = 50) suffering from allergic rhinitis (68%; Vamanshankar et al., 2013). Only one study failed to find a high PD prevalence rate in chronic health condition patients – only a small subset (6%) of patients (n = 36) with Graves disease evidenced PDs (Chattopadhyay, Chakrabarti, & Ghosh, 2012). Several of these studies only assessed for the presence of one PD (e.g., ASPD; Marquine et al., 2014; Woody et al., 2003), but of those that assessed multiple PDs, the most common PDs were schizotypal (Black et al., 2001), and Cluster C PDs generally (Vamanshankar et al., 2013). Among bereaved HIV-seropositive adults (N = 268), antisocial PD was more prevalent among males (8% vs. 2.1% females), whereas BPD was more prevalent among females (29.8% vs. 18.4% males; Hansen, Wang, Stage, & Kragh-Sorensen, 2003). Likewise, in a sample (n = 107) of methadone-maintained HIV-seropositive psychiatric patients, both BPD and antisocial PD were prevalent (37% and 56%, respectively; other PDs not assessed) (Palmer, Salcedo, Miller, Winiarski, & Arno, 2003). In a chart review of HIV status and psychiatric symptoms among psychiatric emergency services patients (N = 28301), a subsample (n = 1178) of these patients were HIV-positive (Bennett, Joesch, Mazur, & Roy-Byrne, 2009). Controlling for gender, race, and age, HIV-positive patients were more likely to carry a diagnosis of BPD (OR = 2.1). In addition, chronic health problems in PD patients is associated with greater treatment utilization and clinical severity. For instance, patients with non-remitted BPD have higher medical services utilization (Frankenburg & Zanarini, 2004), and were more likely to use prescription opioid medication (Frankenburg, Fitzmaurice, & Zanarini, 2014). Further, cancer, back pain, osteoarthritis and fibromyalgia increased the likelihood of opioid use by patients with BPD.

Epidemiological studies support the conclusions drawn from studies with smaller patient samples, indicating that PDs generally, and BPD specifically, have high rates of comorbidity with several chronic health conditions. For example, in an epidemiologically-based sample (n = 1051) of Saint Louis residents, BPD features were associated with the presence of arthritis and obesity (ORs = 2.67 and 2.61), even when controlling for demographic characteristics, Axis I disorders, and any PD diagnoses other than BPD (ORs = 2.64 and 2.94; Powers & Oltmanns, 2013). Similar findings emerged from the NESARC (N = 34,653; El-Gabalawy, Katz, & Sareen, 2010). The presence of hypertension/atherosclerosis, hepatic disease, cardiovascular disease, gastrointestinal disease, arthritis, venereal disease, or other medical condition was associated with a greater likelihood of having BPD, even after adjusting for demographic characteristics and psychopathology. The NESARC data also revealed that PDs were associated with self-reported HIV status (Lopes et al., 2012). Compared to their HIV-negative sex-matched counterparts, HIV-positive men were more likely to have a PD (43.17% vs. 23.28%; OR = 2.50). Likewise, in a national survey of 8580 adults in the United Kingdom (Moran et al., 2007), after controlling for demographic and health-related confounds, avoidant, obsessive compulsive PDs, and BPD diagnoses were associated with stroke (ORs = 4.0, 2.9, and 8.5, respectively); these PDs in addition to paranoid, schizotypal, and schizoid were also associated with ischemic heart disease (ORs = 1.6–7.2). In addition to documenting an association between PDs and pain, the aforementioned large-scale Norwegian population survey (Olsson & Dahl, 2009) revealed that participants endorsing PD criteria were more likely than those not endorsing PD criteria to rate their health poorly (18% vs. 9%), and suffer from asthma (11% vs. 8%). These epidemiological studies provide some support for unique links between BPD and chronic health conditions, as findings held even after controlling for the presence of other PDs.

Longitudinal research has suggested a prospective association of certain PDs and PD features with chronic medical conditions. In a sample of female college students (n = 70), certain features associated with clinical diagnoses of narcissistic PD (i.e., hypersensitivity) predicted physical health problems concurrently and ten years later (Edelstein et al., 2012). In the longitudinal MSAD data set, researchers compared 200 patients who had, at one point, demonstrated remission from BPD, to 64 never-remitted patients with BPD, indicating that never-remitted patients were more likely to have chronic medical conditions (obesity, diabetes, arthritis, hypertension, back pain, incontinence, multiple medical conditions; Frankenburg & Zanarini, 2004). In the 16-year follow-up of this sample, patients who did not recover from BPD were more likely to report being diagnosed with a chronic medical condition compared to patients with BPD who had ever recovered (Keuroghlian, Frankenburg, & Zanarini, 2013).

Together, results suggest high rates of PD among individuals with chronic health conditions. There also appears to be relatively strong support for the concurrent associations between BPD and chronic health conditions in large-scale community and longitudinal work.

Potential Mechanisms

Twelve additional studies, as well as some of the research previously discussed, have examined potential biological and behavioural mechanisms that might explain the associations between PDs and health problems. These studies have used both clinical samples of patients with PDs and subthreshold PDs, as well as laboratory and behavioural approaches. This is an important next step in the field that will facilitate improved treatment and care of a population that, as previously mentioned, places a heavy burden on health care systems.

Several potential mechanisms, transacting in a dynamic manner, likely account for elevated rates of health problems among persons with PDs. Guided by the findings from the literature review and consistent with the BPS framework (Engel, 1977) for understanding health, these mechanisms were conceptualized in terms of biological vulnerabilities, behavioural (psychological) risk factors, and environmental (social) factors. Biological vulnerabilities might include the possibility that PDs are linked with the propensity to experience certain types of health difficulties, such as metabolic problems and inflammatory disorders, as discussed below. Behavioural (psychological) factors likely exacerbate these biological vulnerabilities and include health risk behaviours that directly impact, for example, the metabolic and cardiovascular systems (such as overeating, smoking, and drug use). Finally, environmental (social) factors can include a range of variables, such as insufficient medical care (partly due to stigma and poor understanding of these problems), and poor social and occupational functioning.

Apart from the likely behavioral factors influencing the health problems in PD, the existing literature pinpoints several biological vulnerabilities associated with PDs. One condition implicated in the association between PDs and health problems is metabolic syndrome. This syndrome is characterized by obesity, hypertension, and elevated fasting blood glucose. In one study, psychiatric inpatients with BPD (n = 135) had twice the rate of metabolic syndrome compared to adult primary care (n = 1009) subjects (Kahl et al., 2013). Metabolic syndrome was also associated with use of second-generation antipsychotics among BPD patients. Relatedly, visceral fat (measured via lumbar spine puncture) and insulin-resistance was highest among those with co-occurring BPD and depression (n = 18) compared with BPD alone or healthy controls (Kahl, Bester, et al., 2005). While a biological vulnerability to metabolic syndrome might characterize PDs (and BPD in particular), it is just as possible that health-related behaviours associated with PDs elevate the risk of this syndrome (e.g., impulsive eating, difficulty establishing or sustaining an exercise regimen, substance use problems).

Another potential biological vulnerability factor identified in existing research is related to androgen dysfunction. Specifically, Roepke and colleagues (Roepke et al., 2010) examined androgen dysfunction in persons with BPD and the presence of polycystic ovaries, which has been linked with obesity and other negative health conditions. Inpatients with BPD (n = 31) and healthy controls completed pelvic ultrasounds and hormone assays. Results revealed a heightened proportion of patients with BPD had polycystic ovaries (30.4%, vs. 6.9%). Furthermore, BPD patients had higher BMI, and higher levels of free testosterone, adrostenedione (A) and prolactin compared with controls. The BPD patients with polycystic ovaries did not differ from BPD patients without polycystic ovaries in terms of psychopathology or BMI. Whether BPD is associated with a pre-existing biological vulnerability to hormonal issues that confer vulnerability to polycystic ovaries is unclear, but this possibility should be explored, as should the relative contribution of specific behavioural problems known to contribute to obesity, related hormonal issues (such as disordered eating).

Other markers of poor health may constitute additional biological vulnerability factors in populations suffering from PDs. Findings from one study revealed a higher prevalence of proinflammatory cytokines (TNF-alpha serum concentrations and osteoclastic markers) in patients with co-occurring BPD and depression compared to patients with depression and BPD alone (Kahl, Greggersen, et al., 2006). Similarly, patients with co-occurring depression and BPD (n = 12) evidenced higher concentrations of factors associated with neurogenesis and angiogenesis (VEGF, fibroblast growth factor 2) that have associations with negative health conditions, such as diabetic retinopathy (Kahl et al., 2009) and factors associated with endocrine and immune dysfunction (interleukin-6; Kahl, Bens, et al., 2006). Likewise, 22 female patients with BPD and co-occurring depression were compared to 16 patients with BPD and 20 healthy controls in terms of bone mineral density. Patients with BPD and MDD had higher levels of tumour necrosis alpha, interleukin, and markers of bone turnover than patients with BPD only or controls (Kahl, Rudolf, et al., 2005). In another study, patients with a PD (n = 40) evidenced more markers of immunoreactivity than healthy controls (n = 20), as assessed via lumbar puncture (Coccaro, Lee, Liu, & Mathé, 2012).This association did not remain after controlling for self-reported impulsive aggression. Indeed, indices of immunoreactivity (substance P) have demonstrated associations with aggression and impulsivity in PD patients (n = 38) (Coccaro, Lee, Owens, Kinkead, & Nemeroff, 2012). This finding bears importance as the field moves toward a more dimensional view of PDs, suggesting that certain dimensions of PD features, traits, and behaviors may be contribute to or exacerbate specific biological vulnerability factors.

Additional biological vulnerabilities that may account for some adverse health outcomes in PDs are BMI and other cardiovascular factors. One study found that women with BPD (n = 47) compared with age-matched healthy controls show greater intima-media thickness of common carotid arteries, a marker of atherosclerosis and cardiovascular risk, via ultrasound (Greggersen et al., 2011). Importantly, other findings suggest that BMI may account for this association of BPD with heart disease, arthritis and obesity (Powers & Oltmanns, 2013).

Behavioural (psychological) factors might also account for deleterious health outcomes in PDs. In particular, individuals with PDs often by definition (e.g., in the case of BPD, where diagnostic criteria capture impulsive, self-damaging and suicidal/self-injurious behaviours) engage in a variety of behaviours that result in negative interpersonal, intrapersonal, and adverse health outcomes. Data from several studies suggest that PDs are associated with high rates of health risk behaviours. Specifically, smoking, alcohol use, lack of exercise, overuse of medication and overuse of pain medication, poor health-related lifestyle choices and medical service utilization are all higher among non-recovered BPD patients compared to recovered BPD patients (Frankenburg & Zanarini, 2004; Keuroghlian et al., 2013). Among patients with HIV-seropositive status (N = 303), those high in narcissistic PD features had more HIV risk factors in terms of risky sexual behaviours (Martin, Benotsch, Lance, & Green, 2013). In addition, antisocial PD was associated with HIV risk behaviours among patients receiving treatment for cocaine dependence (Woody et al., 2003). Moreover, in a community sample (n = 1064), impulsive behaviors accounted for the relation between BPD severity and BMI (Iacovino et al., 2014). Thus, deficits in self-care and engagement in impulsive, risky behaviors among persons with PDs may directly and indirectly (such as via BMI) lead to adverse health consequences.

Environmental and social risk factors might include adverse or traumatic events, other environmental stressors, poor access to or quality of healthcare, difficulties associated with poor occupational or social functioning, and so on. Few studies have addressed these factors in the context of PDs and associated health conditions. In the present review, one article indicated that a diagnosis of PD was marginally associated with an environmental risk factor for HIV (history of sexual assault) in a sample (n = 113) of psychiatric patients (Mamabolo, Magagula, Krüger, & Fletcher, 2012). In the studies reviewed, there was no evidence of greater difficulties accessing health services among persons with remitted versus non-remitted BPD (Frankenburg & Zanarini, 2004; Keuroghlian et al., 2013), although non-remitted BPD patients were more likely to have lost or limited employment due to health problems. As such, it is possible that PDs and associated health problems may lead to greater environmental barriers to accessing health care.

Although in its infancy, research in this area has yielded promising data pointing to potential behavioural and biological mechanisms underlying the PD-medical condition relations, although less is known about environmental vulnerabilities in these populations. Given the complex nature of the interrelations of these factors, with reciprocal influences within each level (for instance, with sleep problems and obesity negatively affecting each other), and across levels, future studies are needed to pinpoint how these factors transact in PD samples.