Impact and correlates of sub-optimal social support among patients in HIV care.

Social support (SS) predicts health outcomes among patients living with HIV. We administered a brief, validated measure of SS, the Multifactoral Assessment of Perceived Social Support, within a patient-reported outcomes assessment of health domains in HIV care at 4 U.S. clinics in English and Spanish (n = 708). In univariate analysis, low SS was associated with poorer engagement in care, antiretroviral adherence, and health-related quality of life; current methamphetamine/crystal use, depression, anxiety, and HIV stigma (all p < 0.001); any use of either methamphetamines/crystal, illicit opioids, or cocaine/crack (p = 0.001), current marijuana use (p = 0.012), nicotine use (p = 0.005), and concern for sexually transmitted infection exposure (p = 0.001). High SS was associated with undetectable viral load (p = 0.031). Multivariate analyses found low SS independently associated with depression (risk ratio (RR) 3.72, 95% CI 2.93-4.72), lower adherence (RR 0.76, 95% CI 0.64-0.89), poor engagement in care (RR 2.05, 95% CI 1.44-2.96), and having more symptoms (RR 2.29, 95% CI 1.92-2.75). Medium SS was independently associated with depression (RR 2.59, 95% CI 2.00-3.36), poor engagement in care (RR 1.62, 95% CI 1.15-2.29) and having more symptoms (RR 1.75, 95% CI 1.44-2.13). SS assessment may help identify patients at risk for these outcomes.

Circumstances Surrounding High-risk Sexual Experiences Among Primary Care Patients Living With and Without HIV.

INTRODUCTION: Rates of sexually transmitted infection (STI) are rising in the USA, yet STI risk remains under-addressed by providers, even in HIV care, and with high-risk patients. We interviewed primary care patients living with and without HIV regarding circumstances surrounding sexual risk behavior to identify opportunities for providers to address and reduce STI risk. METHODS: We conducted semi-structured 1:1 interviews with patients living with and without HIV reporting ≥ 1 sex partner and varying STI exposure risk in the past 12 months from four geographically diverse US HIV and primary care clinics. We audio-recorded, transcribed, and coded interviews by circumstance type, using double-coding to ensure inter-coder reliability. We used Fisher's exact and T tests to determine associations with demographic/risk factors. RESULTS: Patients (n = 91) identified a mean of 3 of 11 circumstances. These included substance use (54%), desire for physical/emotional intimacy (48%), lack of HIV/STI status disclosure (44%), psychological drivers (i.e., coping, depression; 38%), personal dislike of condoms (22%), partner condom dislike/refusal (19%), receiving payment for sex (13%), and condom unavailability (9%). Higher proportions of those who were high STI-exposure risk patients, defined as those with ≥ 2 sex partners in the past 3 months reporting never or sometimes using condoms, reported disliking condoms (p = .006); higher proportions of the high-risk and moderate-risk (≥ 2 partners and condom use "most of the time") groups reported substance use as a circumstance (p = .04). CONCLUSION: Circumstances surrounding perceived STI exposure risk were diverse, often overlapping, and dependent on internal, environmental, and partner-related factors and inadequate communication. Meaningful care-based interventions regarding HIV/STI transmission behavior must address the diversity and interplay of these factors.

Anxiety symptoms bias memory assessment in older adults.

BACKGROUND: Older adults with anxiety and/or depression experience additional memory dysfunction beyond that of the normal aging process. However, few studies have examined test bias in memory assessments due to anxiety and/or depressive symptoms. The current study investigated the influence of self-reported symptoms of anxiety and depression on the measurement equivalence of memory tests in older adults. METHOD: This is a secondary analysis of the Advanced Cognitive Training for Independent and Vital Elderly dataset, a randomized controlled trial of community-dwelling older adults. Baseline data were included in this study (n = 2802). Multiple indicators multiple causes modeling was employed to assess for measurement equivalence, differential item functioning (DIF), in memory tests. RESULTS: The DIF was present for anxiety symptoms but not for depressive symptoms, such that higher anxiety placed older adults at a disadvantage on measures of memory performance. Analysis of DIF impact showed that compared with participants scoring in the bottom quartile of anxious symptoms, participants in the upper quartile exhibited memory performance scores that were 0.26 standard deviation lower. CONCLUSION: Anxious but not depressive symptoms introduce test bias into the measurement of memory in older adults. This indicates that memory models for research and clinical purposes should account for the direct relationship between anxiety symptoms and memory tests in addition to the true relationship between anxiety symptoms and memory construct. These findings support routine assessments of anxiety symptoms among older adults in settings in which cognitive testing is being conducted. Copyright © 2016 John Wiley & Sons, Ltd.

Validity assessment of the PROMIS fatigue domain among people living with HIV.

PURPOSE: To evaluate psychometric characteristics and cross-sectional and longitudinal validity of the 7-item PROMIS® Fatigue Short Form and additional fatigue items among people living with HIV (PLWH) in a nationally distributed network of clinics collecting patient reported data at the time of routine clinical care. METHODS: Cross-sectional and longitudinal fatigue data were collected from September 2012 through April 2013 across clinics participating in the Centers for AIDS Research Network of Integrated Clinical Systems (CNICS). We analyzed data regarding psychometric characteristics including simulated computerized adaptive testing and differential item functioning, and regarding associations with clinical characteristics. RESULTS: We analyzed data from 1597 PLWH. Fatigue was common in this cohort. Scores from the PROMIS® Fatigue Short Form and from the item bank had acceptable psychometric characteristics and strong evidence for validity, but neither performed better than shorter instruments already integrated in CNICS. CONCLUSIONS: The PROMIS® Fatigue Item Bank is a valid approach to measuring fatigue in clinical care settings among PLWH, but in our analyses did not perform better than instruments associated with less respondent burden.

Do variations in paraspinal muscle morphology and composition predict low back pain in men?

This longitudinal study aimed to clarify the longstanding controversy over whether variations in paraspinal muscle morphology (e.g., size, composition and asymmetry) are predictors of low back pain (LBP). A sample of 99 Finnish men were included in this population-based longitudinal study. Data were collected through a structured interview, physical examination and magnetic resonance imaging (MRI). Baseline measurements of the lumbar multifidus and erector spinae muscles were obtained from T2-weighted axial images at L3-L4 and L5-S1, and interview data were obtained at baseline, 1- and 15-year follow-ups. Few of the paraspinal muscle parameters investigated were predictors of change in LBP frequency, intensity or sciatica at 1- and 15-year follow-ups in the population-based sample, and findings were not consistent across muscles and spinal levels. However, greater multifidus and erector spinae fatty infiltration at L5-S1 was associated with a higher risk of having continued, frequent, persistent LBP at 1-year follow-up. None of the relationships observed was confounded by body mass index or the amount of physical activity at work or leisure. This longitudinal study provided evidence that variations in paraspinal muscle morphology on MRI have a limited, if not uncertain, role in the short- and long-term predictions of LBP in men.

Measuring depression levels in HIV-infected patients as part of routine clinical care using the nine-item Patient Health Questionnaire (PHQ-9).

Little is known about the psychometric properties of depression instruments among persons infected with HIV. We analyzed data from a large sample of patients in usual care in two US cities (n=1467) using the nine-item Patient Health Questionnaire (PHQ-9) from the PRIME-MD. The PHQ-9 had curvilinear scaling properties and varying levels of measurement precision along the continuum of depression measured by the instrument. In our cohort, the scale showed a prominent floor effect and a distribution of scores across depression severity levels. Three items had differential item functioning (DIF) with respect to race (African-American vs. white); two had DIF with respect to sex; and one had DIF with respect to age. There was minimal individual-level DIF impact. Twenty percent of the difference in mean depression levels between African-Americans and whites was due to DIF. While standard scores for the PHQ-9 may be appropriate for use with individual HIV-infected patients in cross-sectional settings, these results suggest that investigations of depression across groups and within patients across time may require a more sophisticated analytic framework.

Development and content validation of measures assessing adherence barriers and behaviors for use in clinical care.

BACKGROUND: Providers are often unaware of poor adherence to prescribed medications for their patients with chronic diseases. OBJECTIVE: To develop brief, computer-administered patient-reported measures in English and Spanish assessing adherence behaviors and barriers. Design, Participants, and Main Measures: Item pools were constructed from existing measures of medication adherence behaviors and barriers, which informed development of a patient concept elicitation interview guide to identify medication adherence behavior and barrier-related concepts. Two hundred six patients either living with HIV (PLWH) or without were interviewed. Interviews were coded, concepts matched to item pool content, and new items were developed for novel concepts. A provider/investigator team highlighted clinically relevant items. Cognitive interviews were conducted with patients on final candidate items (n = 37). The instruments were administered to 2081 PLWH. KEY RESULTS: Behavioral themes from concept elicitation interviews included routines incorporating time of day, placement, visual cues, and intentionality to miss or skip doses. Barrier themes included health-related (e.g. depressed mood, feeling ill), attitudes/beliefs (e.g., need for medication), access (e.g., cost/insurance problems), and circumstantial barriers (e.g., lack of privacy, disruption of daily routine). The final instruments included 6 behavior items, and 1 barrier item with up to 23 response options. PLWH endorsed a mean (SD) of 3.5 (1.1) behaviors. The 201 PLWH who missed ≥2 doses in the previous week endorsed a mean (SD) of 3.1 (2.5) barriers. The intraclass correlation coefficient (ICC) for the numbers of behaviors endorsed in 61 PLWH after 4-16 days was 0.54 and for the number of barriers for the 20 PLWH with ≥2 missed doses the ICC was 0.89, representing fair and excellent test-retest reliability. CONCLUSION: Measures of medication adherence behaviors and barriers were developed for use with patients living with chronic diseases focusing on clinical relevance, brevity, and content validity for use in clinical care.

Postmenopausal estrogen and estrogen-progestin use and 2-year rate of cognitive change in a cohort of older Japanese American women: The Kame Project.

BACKGROUND: The relation between estrogen and cognition among postmenopausal women remains controversial. Also uncertain is whether the proposed association varies between women taking unopposed estrogen and those taking estrogen combined with progestin. OBJECTIVE: To determine whether unopposed estrogen and combined estrogen-progestin use were associated with the rate of cognitive change in a cohort of older, Japanese American, postmenopausal women. METHODS: A prospective observational study in a population-based cohort of older Japanese Americans (aged > or =65 years) living in King County, Washington. Cognitive performance was measured in 837 women at baseline (1992-1994) and 2-year follow-up (1994-1997) examinations using the 100-point Cognitive Abilities Screening Instrument (CASI). Least squares means general linear models were used to estimate the 2-year rate of cognitive change according to categories of postmenopausal estrogen use. RESULTS: Approximately half of this cohort (n=455) had never used estrogen at any time since menopause, 186 were past users, 132 were current unopposed estrogen users, and 64 were current estrogen-progestin users. The majority of current estrogen users were taking conjugated estrogens, and all women receiving combined therapy were taking medroxyprogesterone acetate. After adjusting for age, education, language spoken at the interview, surgical menopause, and baseline CASI score, women who had never used postmenopausal estrogen improved slightly on the CASI scale (mean adjusted change, 0.79; SEM, 0.19). This change was significantly greater for current unopposed estrogen users (mean adjusted change, 1.68; SEM, 0.36; P=.04) and significantly worse for current estrogen-progestin users (mean adjusted change, -0.41; SEM, 0.50; P =.02) compared with never users. The improvement observed in past users (mean adjusted change, 1.12; SEM, 0.29) was intermediate between the changes for never users and current unopposed estrogen users and not significantly greater than that for never users (P=.35). CONCLUSIONS: Our findings support a modest beneficial association between current unopposed estrogen use and the rate of cognitive change. We also observed a modest detrimental association between current estrogen-progestin use and the rate of cognitive change. The clinical significance of these modest differences, however, is uncertain. Data from large, long-term randomized trials are required before applying this information to the clinical setting.

Assessment of agitation in Alzheimer's disease: the agitated behavior in dementia scale. Alzheimer's Disease Cooperative Study.

OBJECTIVES: To develop and evaluate the psychometric properties of a new measure of agitation, the Agitated Behavior in Dementia scale (ABID). The ABID consists of 16 items designed specifically to evaluate frequency of and caregiver reaction to common agitated behaviors in community-residing dementia patients. DESIGN: The ABID was administered at the baseline assessment of a multi-site controlled treatment study to reduce agitation in Alzheimer's Disease (AD). Reliability was assessed by evaluating internal consistency and test-retest correlations. Validity was assessed by examining correlations with other constructs, including demographics, cognitive status, and overall behavioral disturbance. SETTING: Twenty-one sites across the US, comprising the Alzheimer's Disease Cooperative Study, contributed subjects to the investigation. PARTICIPANTS: A total of 148 community-residing AD patients, living with a spouse or adult relative who acted as an informant. Mean age was 75 years, and mean Mini-Mental State Exam (MMSE) score was 13. MEASUREMENTS: Cognitive status was assessed using the MMSE. Behavioral disturbance was assessed using the Behavior Rating Scale for Dementia of the Consortium to Establish a Registry for Alzheimer's Disease, the Revised Memory and Behavior Problems Checklist, and the Cohen-Mansfield Agitation Inventory. RESULTS: Reliability of the ABID was excellent, with internal consistency of 0.70 and test-retest reliability of 0.60 to 0.73. Validity was confirmed by correlations with related measures and lack of correlation with unrelated constructs. CONCLUSIONS: The ABID is brief, easy to administer, and provides objectively anchored observations of problems. It is a promising measure for studies of community-residing AD patients.

Ethnicity and cognitive performance among older African Americans, Japanese Americans, and Caucasians: the role of education.

This cross-sectional analysis evaluated the association between ethnicity and cognitive performance and determined whether education modifies this association for nondemented older people (103 African Americans, 1,388 Japanese Americans, 2,306 Caucasians) in a study of dementia incidence. African Americans scored lower (median 89 out of 100) than Japanese Americans (93) and Caucasians (94) on the Cognitive Abilities Screening Instrument (CASI). Education affected CA

Determinants of psychomotor speed among 61 pairs of adult male monozygotic twins.

BACKGROUND: Declining psychomotor speed is an indicator of the aging process, and it is influenced by genetics and environmental factors. The present study examined the relative effects of familial aggregation (reflecting a combination of genetics and early environmental influences), and occupational, lifestyle, and health factors on psychomotor speed. METHODS: Hand and foot psychomotor speed was studied with 61 pairs of monozygotic male twins aged 35-67 years from the population-based Finnish Twin Cohort. The determinants of visual simple and choice reaction times were analyzed with multiple regression analysis. RESULTS: Familial aggregation, reflecting genetic influences and shared environmental effects, explained in mean 47% of decision times, 31% of movement times, and 37% of response times (decision time and movement time combined). Age, cardiovascular morbidity, lifetime vigorous and frequent exercise participation, and mean lifetime daily hours sitting at work explained 0-19% of hand psychomotor speed and 0-10% of foot speed, depending on the outcome. The predicted increase in decision times due to the presence of cardiovascular morbidity was 11-35 ms. The predicted increase for hand and contralateral foot response times between ages 45 and 55 was 18-41 ms. Smaller effects were noted for each year of strenuous exercise and each hour/day of average lifetime sitting at work. CONCLUSIONS: Results indicate that cardiovascular status, age, strenuous exercise, and work play a role in psychomotor speed, but a rather minor one. In contrast, genetic and shared early environmental influences as revealed from familial aggregation were relatively strong, yet a major proportion of the variability in psychomotor speed remained unexplained.

Anxiety of Alzheimer's disease: prevalence, and comorbidity.

BACKGROUND: Anxiety may be associated with psychiatric morbidity, disability, increased health care utilization, and mortality in Alzheimer's disease (AD) patients as it is in the general adult population. However, the phenomenology of anxiety symptoms in AD and its relationship to dementia progression, comorbid depression, and the presence of other problematic behaviors have not yet been examined. METHOD: Data on anxiety symptoms and their coexistence with other factors were obtained in 523 community-dwelling AD patients through interviews with their caregivers and direct physical examination. The prevalence of anxiety symptoms and their association to patient depression, other behavioral problems, gender, and age was investigated. RESULTS: Anxiety symptoms were common, occurring in 70% of subjects. Anxiety symptoms were significantly correlated with ADL impairment and other behavioral disturbances, including wandering, sexual misconduct, hallucinations, verbal threats, and physical abuse. Comorbidity of anxiety-depression was also prevalent: 54% of the sample had both anxiety and depression symptoms. ADL impairment and problem behaviors were significantly associated with comorbidity; however, the latter association was explained entirely by the presence of anxiety. CONCLUSION: Anxiety symptoms were common and significantly related to ADL and additional neuropsychiatric problems in this sample. These results indicate the need for additional research into the phenomenology of anxiety and comorbid anxiety-depression in AD and for the development and investigation of effective assessment and treatment of anxiety in AD clinical practice.

Disc degeneration and bone density in monozygotic twins discordant for insulin-dependent diabetes mellitus.

The effects of insulin-dependent diabetes mellitus on bone density and connective tissue degeneration have theoretical interest and practical relevance. Several experimental studies in animals have demonstrated the harmful effects of insulin deficiency on connective tissues. However, clinical studies in humans have produced somewhat contradictory results, most likely due to difficulties controlling for general degeneration and factors associated with diabetes. In nine pairs of monozygotic twins discordant for insulin-dependent diabetes mellitus, we compared femoral and lumbar bone mineral density (assessed by dual-energy x-ray absorptiometry) and spinal degeneration (assessed by magnetic resonance imaging). The bone densities were, on average, 0.1-0.3% lower (p = 0.87-0.96) in diabetic patients. However, after controlling for smoking, we found that the bone density in the femoral neck was 2.5% (0.025 g/cm2) lower in diabetic individuals than in their twins (p = 0.09). The five magnetic resonance imaging parameters used to evaluate disc degeneration did not differ between diabetic patients and their twins. In conclusion, our results provide no evidence that insulin-dependent diabetes mellitus has any major effect on bone density or disc degeneration.

Characteristics of sleep disturbance in community-dwelling Alzheimer's disease patients.

This study examined the frequency, predictors, and impact of sleep problems in a population-based sample of 205 Alzheimer's disease (AD) patients. Sleeping more than usual and early morning awakenings were the most common sleep problems reported but were the least disturbing behaviors for caregivers. Night-time awakenings were less common but were most disturbing to caregivers. Using logistic regression analyses, the factors most strongly associated with night awakenings among patients were male gender, greater memory problems, and decreased functional status. Patient depression increased the risk for caregivers to rate patient sleep problems as more disturbing overall. Cluster analyses revealed three characteristic groups of patients who awakened caregivers: one group was inactive during the day but had few other behavior problems; one group had increased levels of fearfulness, fidgeting, and occasional sadness; and the third group had multiple behavior problems, including frequent episodes of sadness, fearfulness, inactivity, fidgeting, and hallucinations. These findings indicate that the nature of sleep problems in AD is multifaceted; future research on the occurrence and treatment of sleep disturbance in dementia patients should consider the patterns of individual differences that may influence its development.

The effect of lifelong exercise on psychomotor reaction time: a study of 38 pairs of male monozygotic twins.

PURPOSE: The aim was to study the effect of lifetime physical activity on psychomotor speed. METHODS: Foot and dominant hand visual simple and choice psychomotor reaction times were studied among monozygotic twins (38 pairs) aged 35-69, discordant for lifetime exercise histories. RESULTS: There was a trend that some components of psychomotor reaction time were faster for frequent than for occasional exercisers, but the findings were not consistent for the hand and feet. After controlling for occupational physical activity, only choice decision time for the hand (26 ms, P < 0.01) and choice reaction time for the contralateral foot (51 ms, P < 0.05) both remained 7% faster. There was no trend for systematic differences in reaction times between twins engaged in regular exercise versus their siblings exercising infrequently. CONCLUSIONS: Results suggest a somewhat smaller effect of exercise than reported in previous studies. Reaction time may be significantly affected only by vigorous, frequent exercise. Thus, health promotion through exercise may be unlikely to have notable effects on reaction time.

Lifetime exercise and disk degeneration: an MRI study of monozygotic twins.

Participation in some competitive sports has been shown to increase disk degeneration; however, the long-term effects of recreational physical activities are unclear. We investigated the effects of endurance exercise and power sports on disk degeneration in monozygotic male twins with contrasting lifetime exercise histories. The effects of endurance exercise were studied in 22 discordant twin pairs (mean lifetime frequencies of 3.9 vs 1.1 times/wk), and the effects of power sports were investigated in 12 discordant pairs (2,300 vs 200 h of weightlifting). The age range of the twins was from 35 to 69 yr. No differences in MRI findings between co-twins discordant for endurance exercise were found at any of the spinal regions. Subjects with more power sport involvement had greater disk degeneration in the T6-T12 region (P < 0.03), but similar findings were not present in the lumbar spine. Controlling for recalled back injuries, occupational loading, smoking, and driving did not significantly affect the results. No signs of beneficial or harmful effects of lifetime endurance exercise on disk degeneration were seen. Increased power sport participation was associated with slightly greater disk degeneration in the lower thoracic spine, but not in the lumbar spine.

Similarities in degenerative findings on magnetic resonance images of the lumbar spines of identical twins.

Although the etiology of most degenerative changes in the lumbar spine is unclear, genetic factors may play an important role. To investigate this link, we reviewed magnetic resonance images of the lumbar spines of identical twins to assess the degree of similarities in degenerative findings in the discs. Observers who were blinded to twinship evaluated sagittal T1-weighted and T2-weighted magnetic resonance images of the lumbar spines of forty male identical twins (twenty pairs) with respect to changes in the end plates, desiccation of the discs, bulging or herniated discs, and decrease in the height of the disc space. Similarities between co-twins were significantly greater than would be expected by chance. Whereas smoking status and age explained 0 to 15 per cent of the variability in the various degenerative findings in the discs, 26 to 72 per cent of the variability was explained with the addition of a variable representing co-twin status. These findings are compatible with a marked genetic influence and warrant further investigation.

Determinants of isokinetic and psychophysical lifting strength and static back muscle endurance: a study of male monozygotic twins.

STUDY DESIGN: Retrospective cohort. OBJECTIVES: To determine the relative contributions of anthropometric factors, physical activity, back and neck pain, overall health, and familial aggregation (the combined effects of genetics and childhood environment) to different measurements of adult back muscle function. SUMMARY OF BACKGROUND DATA: Many methods of muscle testing are employed in the attempt to predict, prevent, treat, and rehabilitate low back pain. Poor correlations between the test results suggest that they are measuring different attributes and have different determinants. METHODS: Muscle function tests, magnetic resonance images, and a detailed interview were obtained in 65 pairs of monozygotic male twins. RESULTS: Familial aggregation was the strongest determinant of isokinetic and psychophysical lifting and static back endurance, explaining 56%, 32%, and 15% of the variances, respectively, beyond that which age alone predicted. Back pain and physical loading in work and leisure explained 2%, 0%, and 23% of the variances. CONCLUSIONS: The combined effects of genetics and childhood environment play a dominant role in determining adult back muscle function. Physical loading at work and leisure, back and neck pain history, overall health, and anthropometric factors had a comparatively minor role, suggesting that the potential of interventions to increase and sustain back muscle function in healthy adults, measured through these tests, may be limited. The relative contributions of constitutional, behavioral, and environmental factors differ substantially in the three tests, and provide insights into what these commonly used tests actually reflect or measure. This knowledge can be used to guide more appropriate selection and interpretation of results of back muscle function tests.

1995 Volvo Award in clinical sciences. Determinants of lumbar disc degeneration. A study relating lifetime exposures and magnetic resonance imaging findings in identical twins.

STUDY DESIGN: Retrospective cohort. OBJECTIVES: To investigate the effects of lifetime exposure to commonly suspected risk factors on disc degeneration using magnetic resonance imaging, and to estimate the effects of these suspected risk factors relative to age and familial aggregation, reflecting genetic and shared environmental influences. SUMMARY OF BACKGROUND DATA: Structural and biochemical changes associated with disc degeneration are suspected as the underlying conditions of many back-related symptoms. Little is known about the determinants of disc degeneration. METHODS: Based on lifetime discordance in suspected environmental risk factors for disc degeneration, 115 male identical twin pairs were selected. An in-depth interview was conducted of occupational and leisure time physical loading, driving, and smoking. Disc degeneration was evaluated using observational and digital magnetic resonance imaging assessment methods. RESULTS: Heavier lifetime occupational and leisure physical loading was associated with greater disc degeneration in the upper lumbar levels (P = 0.055 - 0.001), whereas sedentary work was associated with lesser degeneration (P = 0.006). These univariate associations did not reach statistical significance in the lower lumbar region. In multivariate analyses of the upper lumbar levels, the mean job code explained 7% of the variability in observational disc degeneration scores; the addition of age explained 16%, and familial aggregation improved the model such that 77% of the variability was explained. In the lower lumbar levels, leisure time physical loading entered the multivariate model, explaining 2% of the variability. Adding age explained 9%, and familial aggregation raised the variability in disc degeneration scores explained to 43%. CONCLUSIONS: The present study findings suggest that disc degeneration may be explained primarily by genetic influences and by unidentified factors, which may include complex, unpredictable interactions. The particular environmental factors studied, which have been among those most widely suspected of accelerating disc degeneration, had very modest effects.

Magnetic resonance imaging findings and their relationships in the thoracic and lumbar spine. Insights into the etiopathogenesis of spinal degeneration.

STUDY DESIGN: Descriptive epidemiologic study about magnetic resonance imaging findings in the spine. OBJECTIVES: To describe the prevalence of magnetic resonance imaging findings in a general population at spinal levels T6-S1, and to examine the relationships of these findings within each spinal level and between levels. SUMMARY OF BACKGROUND DATA: The prevalence of specific findings and the associations between findings and spinal levels can provide general insights into the etiopathogenesis of spinal degeneration. METHODS: Subjects consisted of 232 men from a population sample (mean age 49.3 years). Signal intensity, disc bulging, disc herniation, and endplate irregularities were among 11 findings assessed from magnetic resonance images. RESULTS: The disc signal intensities were assessed to be lowest in the lumbar and middle thoracic regions. Disc bulging and disc height narrowing were most common in the lower levels of both the thoracic and lumbar regions. All magnetic resonance imaging findings except herniations and endplate irregularities were clearly associated with age. Osteophytes were most highly associated with disc bulging in levels T6-L3, and with endplate irregularities in the lower lumbar levels. Disc herniations were not consistently associated with any other findings. The disc levels that most highly correlated are grouped as follows: T6-T10, T10-L4, and L4-S1. CONCLUSIONS: With the exception of endplate irregularities and herniations, the magnetic resonance imaging findings appeared to be associated with the same pathogenic process. The interaction of mechanical factors and spinal structures varies between spinal levels, and the degeneration common in the lower parts of the thoracic and lumbar spine could be an outcome of vulnerability for torsional forces. Some gross guidelines for grouping findings can be drawn from disc level correlations.