Improving diagnosis and treatment of knee osteoarthritis in persons with type 2 diabetes: development of a complex intervention

BACKGROUND

Symptomatic knee osteoarthritis (OA) commonly co-occurs in people with type 2 diabetes (T2DM) and increases the risk for diabetes complications, yet uptake of evidence-based treatment is low. We combined theory, stakeholder involvement and existing evidence to develop a multifaceted intervention to improve OA care in persons with T2DM. This was done in partnership with Arthritis Society Canada to leverage the existing infrastructure and provincial funding for community arthritis care.

METHODS

Each step was informed by a User Advisory Panel of stakeholder representatives, including persons with lived experience. First, we identified the target groups and behaviours through consulting stakeholders and current literature. Second, we interviewed persons living with T2DM and knee OA (n = 18), health professionals (HPs) who treat people with T2DM (n = 18) and arthritis therapists (ATs, n = 18) to identify the determinants of seeking and engaging in OA care (patients), assessing and treating OA (HPs) and considering T2DM in OA treatment (ATs), using the Theoretical Domains Framework (TDF). We mapped the content to behavioural change techniques (BCTs) to identify the potential intervention components. Third, we conducted stakeholder meetings to ascertain the acceptability and feasibility of intervention components, including content and modes of delivery. Fourth, we selected intervention components informed by prior steps and constructed a programme theory to inform the implementation of the intervention and its evaluation.

RESULTS

We identified the barriers and enablers to target behaviours across a number of TDF domains. All stakeholders identified insufficient access to resources to support OA care in people with T2DM. Core intervention components, incorporating a range of BCTs at the patient, HP and AT level, sought to identify persons with knee OA within T2DM care and refer to Arthritis Society Canada for delivery of evidence-based longitudinal OA management. Diverse stakeholder input throughout development allowed the co-creation of an intervention that appears feasible and acceptable to target users.

CONCLUSIONS

We integrated theory, evidence and stakeholder involvement to develop a multifaceted intervention to increase the identification of knee OA in persons with T2DM within diabetes care and improve the uptake and engagement in evidence-based OA management. Our partnership with Arthritis Society Canada supports future spread, scalability and sustainability. We will formally assess the intervention feasibility in a randomized pilot trial.

Formulating Knee Osteoarthritis Management Plans Taking Type 2 Diabetes Into Account: Qualitative Study of Arthritis Therapists Using Theoretical Domains Framework

OBJECTIVE

Delivering person-centered care in individuals with knee osteoarthritis (OA) necessitates consideration of other chronic conditions that frequently co-occur. We sought to understand the extent to which arthritis therapists consider type 2 diabetes mellitus (T2DM) when treating persons with knee OA and concomitant T2DM, and barriers to doing so.

METHODS

We conducted 18 semistructured telephone interviews with arthritis therapists working within a provincially funded arthritis care program (Arthritis Society Canada) in Ontario, Canada. We first analyzed interviews deductively using the Theoretical Domains Framework (TDF) to comprehensively identify barriers and enablers to health behaviors. Then, within TDF domains, we inductively developed themes.

RESULTS

We identified 5 TDF domains as prominently influencing the behavior of arthritis therapists considering concomitant T2DM when developing a knee OA management plan. These were as follows: therapists' perceived lack of specific knowledge around comorbidities including diabetes; the lack of breadth in skills in behavioral change techniques to help patients set and reach their goals, particularly when it came to physical activity; variable intention to factor a patient's comorbidity profile to influence their treatment recommendations; the perception of their professional role and identity as joint focused; and the environmental context with lack of formalized follow-up structure of the current Arthritis Society Canada program that limited sufficient patient monitoring and follow-up.

CONCLUSION

Within the context of a Canadian arthritis program, we identified several barriers to arthritis therapists considering T2DM in their management plan for persons with knee OA and T2DM. These results can help inform strategies to improve person-centered OA care and overall health outcomes.

Understanding the behavioural determinants of seeking and engaging in care for knee osteoarthritis in persons with type 2 diabetes mellitus: A qualitative study using the theoretical domains framework

Objectives

Symptomatic knee osteoarthritis (OA) frequently co-occurs in individuals with type 2 diabetes mellitus (T2DM). In the context of T2DM, OA is often underdiagnosed and undertreated. To elucidate strategies to improve OA care in persons with T2DM, we assessed their perceptions of the barriers and enablers to seeking and engaging in OA care.

Design

We conducted semi-structured interviews with 18 individuals with T2DM and symptomatic knee OA in Ontario, Canada. Transcripts were deductively coded using the Theoretical Domains Framework (TDF), an implementation science framework that incorporates theoretical domains of behaviour determinants, which can be linked to behaviour change techniques. Within each of the relevant domains, data were thematically analyzed to generate belief statements.

Results

Seven of the TDF domains prominently influenced the behaviour to seek and engage in OA care. Participants described insufficient receipt of OA knowledge to fully engage in care (knowledge), feeling incapable of participating in physical activity due to joint pain (beliefs about capabilities), uncertainty about effectiveness of therapies (optimism) and lack of guidance from health care providers and insufficient access to community programs/supports (environmental context and resources). Key enablers were strong social support (social influences), sources of accountability (behavioural regulation) and experiencing benefit from treatment (reinforcement). Participants did not see concomitant T2DM as limiting the desire to seek OA care.

Conclusions

Among individuals with symptomatic knee OA and T2DM, we identified behavioural determinants of seeking and engaging in OA care. These will be mapped to behavioural change techniques to inform development of a complex intervention.

Barriers and enablers to health care providers assessment and treatment of knee osteoarthritis in persons with type 2 diabetes mellitus: A qualitative study using the Theoretical Domains Framework

Objectives

Symptomatic knee osteoarthritis (OA) commonly co-exists in persons with Type 2 diabetes (T2DM) and may impede diabetes self-management. Yet, OA is often underdiagnosed and undertreated due to competing health care demands. We sought to determine healthcare providers' (HCPs') perceptions of the barriers and enablers to assessing and treating knee OA in persons with T2DM.

Design

We conducted 18 semi-structured telephone interviews with HCPs who manage persons with T2DM (family physicians, endocrinologists, diabetes educators). Interviews were analyzed deductively using Theoretical Domains Framework (TDF), a framework developed to comprehensively identify behavioural determinants. Within relevant domains, data were thematically analyzed to generate belief statements, and these were compared across the different HCP disciplines.

Results

Six TDF domains influenced HCPs behaviour to assess and treat knee OA in persons with T2DM. For all HCPs, important barriers included not seeing assessment/treatment of joint pain as a priority for their patients (intention), and insufficient access to required resources such as physiotherapy to treat OA (environmental context and resources). Endocrinologists and diabetes educators perceived having insufficient knowledge and skills to identify and manage OA (knowledge, skills), did not consider it within their professional role to do so (professional role and identity), and perceived other physicians would not want to receive a referral for OA care (social influences).

Conclusions

We identified barriers and enablers encountered by diabetes HCPs to assessing and treating knee OA in persons with T2DM involving multiple domains of the TDF. These will help inform development of a complex intervention to improve health outcomes.

Minimal clinically important difference for improvement in six-minute walk test in persons with knee osteoarthritis after total knee arthroplasty

BACKGROUND

The interpretability of the six-minute walk test (6MWT) in individuals with knee osteoarthritis (OA) is unclear. We aimed to determine the minimal clinically important difference (MCID) for improvement in 6MWT in persons with knee OA at 12 months after total knee arthroplasty (TKA), and if it differed by baseline walking ability.

METHODS

Participants with knee OA were assessed 1 month pre- and 12 months post-TKA, including completion of 6MWT. At 12 months, participant-perceived change in walking ability was assessed on an 8-point Likert scale ranging from "extremely worse" to "extremely better". Using logistic regression, ROC curves examined the ability of change in 6MWT distance to discriminate those who perceived walking was improved. MCID was selected overall and then by quartile of baseline 6MWT distance using the Youden method.

RESULTS

Two hundred seventy-eight participants were included: mean age 67 years (SD 8.5), 65.5% female, mean pre-TKA 6MWT distance 323.1 (SD 104.7) m, and mean 12-mo 6MWT distance 396.0 (SD 111.9) m. The overall MCID was 74.3 m (AUC 0.65). Acceptable model discrimination (AUC > 0.70) was achieved for individuals in the lowest quartiles of baseline 6MWT distance: Quartile 1: MCID 88.63 m (AUC 0.73); Quartile 2: MCID 84.47 m (AUC 0.72).

CONCLUSIONS

In persons with knee OA 12 months post-TKA, 6MWT MCID is dependent on baseline walking ability. Poor model discrimination for those in the highest (best) quartiles of baseline walking ability raise questions about 6MWT use across the full spectrum of walking ability. Further research is needed to better understand use of 6MWT as a performance-based measure of physical function for persons with knee OA.

Comorbidities do not limit improvement in pain and physical function after total knee arthroplasty in patients with knee osteoarthritis: the BEST-Knee prospective cohort study

OBJECTIVE

To assess the relationship between comorbidities and amount of improvement in pain and physical function in recipients of total knee arthroplasty (TKA) for knee osteoarthritis (OA).

DESIGN

Prospective cohort study.

SETTING

Two provincial central intake hip and knee centres in Alberta, Canada.

PARTICIPANTS

1051 participants (278 in 6-minute walk test (6MWT) subset), ≥30 years of age with primary knee OA referred for consultation regarding elective primary TKA; assessed 1 month prior and 12 months after TKA.

PRIMARY AND SECONDARY OUTCOME MEASURES

Pre-post TKA change in knee OA pain (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)), physical function (Knee injury and Osteoarthritis Outcome Score (KOOS) Physical Function Short-Form) and 6MWT walking distance; and the reporting of an acceptable symptom state (Patient Acceptable Symptom State (PASS)) at 12 months after TKA.

RESULTS

Mean participant age was 67 years (SD 8.8), 59% were female and 85% reported at least one comorbidity. Individuals with a higher number of comorbidities had worse pre-TKA and post-TKA scores for pain, physical function and 6MWT distance. At 12-month follow-up, mean changes in pain, function and 6MWT distance, and proportion reporting a PASS, were similar for those with and without comorbidities. In multivariable regression analysis, adjusted for potential confounders and clustering by surgeon, no specific comorbidities nor total number of comorbidities were associated with less improvement in pain, physical function or 6MWT distance at 12 months after TKA. Patients with diabetes (OR 0.64, 95% CI 0.44 to 0.94) and a higher number of lower extremity troublesome joints (OR 0.85, 95% CI 0.76 to 0.96) had lower odds of reporting a PASS.

CONCLUSION

For individuals with knee OA, comorbid conditions do not limit improvement in pain, physical function or walking ability after TKA, and most conditions do not impact achieving an acceptable symptom state.

Impact of Osteoarthritis on Difficulty Walking: A Population-Based Study

OBJECTIVE

To assess the relationship of hip and knee osteoarthritis (OA) to walking difficulty.

METHODS

A population cohort ages ≤55 years recruited from 1996 to 1998 (n = 28,451) completed a standardized questionnaire assessing demographics, health conditions, joint symptoms, and functional limitations, including difficulty walking in the past 3 months. Survey data were linked to health administrative databases; self-report and administrative data were used to identify health conditions. Hip/knee OA was defined as self-reported swelling, pain, or stiffness in a hip or knee lasting ≥6 weeks in the past 3 months without an inflammatory arthritis diagnosis. Using multivariable logistic regression, we examined the determinants of walking difficulty and constructed a clinical nomogram.

RESULTS

A total of 18,490 cohort participants were eligible (mean age 68 years, 60% women), and 25% reported difficulty walking. Difficulty walking was significantly and independently associated with older age, female sex, body mass index, and several health conditions. Of the conditions examined, the likelihood of walking difficulty was greatest with hip and knee OA and increased with the number of hip/knee joints affected. The predicted probability of difficulty walking for a 60-year-old middle-income, normal-weight woman was 5-10% with no health conditions, 10-20% with diabetes mellitus and cardiovascular (CV) disease, 40% with OA in 2 hips/knees, 60-70% with diabetes mellitus, CV disease, and OA in 2 hips/knees, and 80% with diabetes mellitus, CV disease, and OA in all hips/knees.

CONCLUSION

In a population cohort, symptomatic hip/knee OA was the strongest contributor to walking difficulty. Given the importance of walking to engagement in physical activity for chronic disease management, greater attention to OA is warranted.

Primary care physicians' perceptions about and confidence in deciding which patients to refer for total joint arthroplasty of the hip and knee

OBJECTIVE

The purpose of this study is to examine the perceptions of primary care physicians (PCPs) regarding indications, contraindications, risks and benefits of total joint arthroplasty (TJA) and their confidence in selecting patients for referral for TJA.

DESIGN

PCPs recruited from among those providing care to participants in an established community cohort with hip or knee osteoarthritis (OA). Self-completed questionnaires were used to collect demographic and practice characteristics and perceptions about TJA. Confidence in referring appropriate patients for TJA was measured on a scale from 1 to 10; respondents scoring in the lowest tertile were considered to have 'low confidence'. Descriptive analyses were conducted and multiple logistic regression was used to determine key predictors of low confidence.

RESULTS

212 PCPs participated (58% response rate) (65% aged 50+ years, 45% female, 77% >15 years of practice). Perceptions about TJA were highly variable but on average, PCPs perceived that a typical surgical candidate would have moderate pain and disability, identified few absolute contraindications to TJA, and overestimated both the effectiveness and risks of TJA. On average, PCPs indicated moderate confidence in deciding who to refer. Independent predictors of low confidence were female physicians (OR = 2.18, 95% confidence interval (CI): 1.06-4.46) and reporting a 'lack of clarity about surgical indications' (OR = 3.54, 95% CI: 1.87-6.66).

CONCLUSIONS

Variability in perceptions and lack of clarity about surgical indications underscore the need for decision support tools to inform PCP - patient decision making regarding referral for TJA.

Effects of exercise on bone mass in young women with anorexia nervosa

PURPOSE

The response of bone to exercise in women with anorexia nervosa (AN) is unclear. We investigated the associations between bone mineral density (BMD) and exercise performed while ill and while recovered in women with a history of AN.

METHODS

A cross-sectional study was conducted with 141 women with AN (85 ill; 56 recovered), aged 17-40 yr. BMD at the lumbar spine (LS), femoral neck (FN), and total body (TB) was measured by dual-energy x-ray absorptiometry. Life History Calendar and Minnesota Leisure Time Physical Activity interviews were used to collect lifetime illness and exercise histories (amount and bone loading type). Average hours per week of each of moderate (MOD) and high (HI) bone loading exercise were determined for three illness phases: "before ill," "while ill," and "while recovered." Participants were categorized into four exercise groups for each phase: MOD-ONLY, HI-ONLY, BOTH, and NEITHER (reference group). Weight-adjusted BMD z-scores were compared in the exercise groups by multivariable linear regression, adjusting for illness duration and severity, and exercise during the other illness phases.

RESULTS

In ill participants, MOD-ONLY "while ill" had lower BMD at LS (β = -0.69, 95% confidence interval (CI) = -1.02 to -0.05) and TB (β = -0.73, 95% CI = -1.31 to -0.15) than the NEITHER group. In recovered participants, HI-ONLY "while recovered" had higher BMD at FN (β = 0.95, 95% CI = 0.15-1.75) and TB (β = 0.79, 95% CI = 0.07-1.51) than the NEITHER group.

CONCLUSIONS

The effect of exercise on bone in AN patients is dependent on both the type of mechanical loading and the phase of illness during which it was performed. Excessive moderate loading exercise while ill may put patients at higher risk of low bone mass, but high bone loading activities may provoke bone accrual during recovery.

The multidimensionality of sleep quality and its relationship to fatigue in older adults with painful osteoarthritis

OBJECTIVE

To evaluate subjective sleep quality and its relationship to fatigue in older adults with osteoarthritis (OA).

METHOD

In a community cohort with hip/knee OA, subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) and fatigue was measured by the Profile of Mood States - Fatigue subscale (POMS-F). Correlates of sleep quality and fatigue were determined by standardized interviews including socio-demographics, OA severity (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) summary score), comorbidity, depression (Center for Epidemiologic Studies Depression Scale, CES-D), stressful life events, daytime napping, symptoms of restless legs syndrome (RLS) and prior sleep disorder diagnoses. Logistic regression examined correlates of poor sleep (PSQI score>5). Linear regression evaluated the relationship between poor sleep and fatigue, and the effect of napping on this relationship.

RESULTS

In 613 respondents, mean age was 78 years, 78% were female, 11% had concomitant fibromyalgia, and 26% had 3+ comorbid conditions. Responses indicated moderate OA severity. Seventy percent reported poor sleep; 25% met criteria for RLS and 6.5% reported a diagnosed sleep disorder. Independent correlates of poor sleep were: greater arthritis severity (adjusted odds ratio (OR) per unit increase in WOMAC score=1.03, P<0.0001), 3+ comorbid conditions (adjusted OR=1.88; P=0.03), depressed mood (adjusted OR per unit increase in CES-D score=1.09, P<0.0001), and RLS (adjusted OR=1.87; P=0.02). Controlling for previously reported fatigue correlates, poor sleep was significantly associated with greater fatigue (parameter estimate=1.63, P=0.0003) and napping did not moderate this relationship (P=0.55 for the interaction between napping and poor sleep).

CONCLUSIONS

Among older people with OA, poor sleep is highly prevalent and significantly linked with fatigue. Identifying the nature of sleep disturbances in OA is important as treatment of sleep disturbances may reduce OA-related fatigue.

Risk factors for low bone mass in healthy 40-60 year old women: a systematic review of the literature

Based on a systematic review of the literature, only low body weight and menopausal status can be considered with confidence, as important risk factors for low BMD in healthy 40-60 year old women. The use of body weight to identify high risk women may reduce unnecessary BMD testing in this age group.

INTRODUCTION

BMD testing of perimenopausal women is increasing but may be unnecessary as fracture risk is low. Appropriate assessment among younger women requires identification of risk factors for low BMD specific to this population.

METHODS

We conducted a systematic literature review of risk factors for low BMD in healthy women aged 40-60 years. Articles were retrieved from six databases and reviewed for eligibility and methodological quality. A grade for overall strength of evidence for each risk factor was assigned.

RESULTS

There was good evidence that low body weight and post-menopausal status are risk factors for low BMD. There was good or fair evidence that alcohol and caffeine intake, and reproductive history are not risk factors. There was inconsistent or insufficient evidence for the effect of calcium intake, physical activity, smoking, age at menarche, history of amenorrhea, family history of OP, race and current age on BMD.

CONCLUSIONS

Based on current evidence in Caucasians, we suggest that, in healthy women aged 40-60 years, only those with a low body weight (< 70 kg) be selected for BMD testing. Further research is necessary to determine optimal race-specific discriminatory weight cut-offs and to evaluate the risk factors for which there was inconclusive evidence.

A prospective investigation of the relations among cognitive dietary restraint, subclinical ovulatory disturbances, physical activity, and bone mass in healthy young women

BACKGROUND

Cognitive dietary restraint (CDR) may mediate subclinical ovulatory disturbances, which may result in loss of bone mineral density (BMD). CDR is associated with greater physical activity, which may modify the effect of CDR and ovulatory disturbances on bone mass.

OBJECTIVE

We aimed to investigate the relations among CDR, ovulatory disturbances, and physical activity and their effect on BMD in healthy premenopausal women over a 2-y period.

DESIGN

In this prospective cohort study, key explanatory factors, important covariates, and BMD were measured at baseline and at 12 and 24 mo; 225 women completed the baseline assessment, and 189 completed the study. CDR was measured with the Three-Factor Eating Questionnaire, and physical activity was measured with the Baecke scale. An average of 9.8 menstrual cycles in 2 y were monitored by using salivary progesterone measurements and urinary ovulation detection kits. Ovulatory disturbances included anovulatory cycles or short luteal phase lengths of <10 d. BMD at the lumbar spine, femoral neck, and total body was measured by using dual-energy X-ray absorptiometry. General linear mixed modeling was used to determine predictors of change in BMD over time.

RESULTS

CDR was not associated with ovulatory disturbances or changes in BMD. The average annual rate of change in lumbar spine BMD was decreased by 0.01 g/cm(2) in women who had experienced > or =3 monitored cycles with ovulatory disturbances (P = 0.02).

CONCLUSIONS

CDR did not predict bone loss, and there was no relation between CDR and ovulatory disturbances. Ovulatory disturbances had a negative effect on the rate of change at the lumbar spine. The cause of these disturbances is unknown.

Computer use associated with poor long-term prognosis of conservatively managed lateral epicondylalgia

STUDY DESIGN

Multicenter prospective design with a cohort of patients with lateral epicondylalgia commencing physical therapy.

OBJECTIVE

To identify key factors associated with long-term prognosis of conservatively managed lateral epicondylalgia.

BACKGROUND

The response to conservative management of lateral epicondylalgia is inconsistent and the rate of recovery varies widely among individuals. The reasons for these discrepancies are not understood. The identification of factors associated with prognosis will aid in the prediction of patient outcomes.

METHODS AND MEASURES

Sixty patients with lateral epicondylalgia, recruited from 9 sports medicine clinics and 2 hospital outpatient physical therapy departments in Ontario, Canada, were followed for 6 months. A baseline clinical assessment was conducted on each participant using standard physical therapy techniques. The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire and a 100-mm pain visual analog scale (VAS) were completed at baseline and 6 months later.

RESULTS

The key factor associated with both 6-month DASH and pain VAS scores was repetitive-work tasks (DASH, 9.8 [P < .011; pain VAS, 13.1 mm [P = .0105]). A subanalysis indicated that women were more likely than men to have cervical joint signs and, among women, positive cervical articular signs were also associated with higher final DASH and pain VAS scores.

CONCLUSIONS

Although many of the participants identified sports activities as the cause of their injury, these findings emphasize the importance that a patient's work tasks can have on recovery of lateral epicondylalgia. This would suggest that management should perhaps focus on work stations, postures, and behaviors.

Factors associated with prognosis of lateral epicondylitis after 8 weeks of physical therapy

OBJECTIVE

To identify key factors associated with outcomes of patients who underwent 8 weeks of physical therapy (PT) for lateral epicondylitis.

DESIGN

Multicenter prospective design with inception cohort of lateral epicondylitis patients commencing PT. Baseline clinical examinations were conducted by 1 physical therapist; self-report outcome measures were completed at baseline and 8 weeks later.

SETTING

Nine private sports medicine clinics and 2 hospital outpatient departments in Ontario, Canada.

PARTICIPANTS

Eighty-three patients with unilateral lateral epicondylitis identified by the treating physical therapists.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The final scores of the Disability of the Arm, Shoulder and Hand (DASH) questionnaire and a vertical pain visual analog scale (VAS) were used as the dependent variables.

RESULTS

The final prognostic model for the 8-week DASH scores included the baseline score (95% confidence interval [CI], 0.34-0.66), sex (female) (95% CI, 3.3-14.5), and self-reported nerve symptoms (95% CI, 0.8-13.8). The model for the 8-week VAS scores included the baseline score (95% CI, 0.01-0.37), sex (female) (95% CI, 0.4-18.2), and self-reported nerve symptoms (95% CI, 4.7-25.5). A subanalysis indicated that women were more likely than men to have work-related onsets, repetitive keyboarding jobs, and cervical joint signs. Among women, these factors were associated with higher final DASH and VAS scores.

CONCLUSIONS

Women and patients who report nerve symptoms are more likely to experience a poorer short-term outcome after PT management of lateral epicondylitis. Work-related onsets, repetitive keyboarding jobs, and cervical joint signs have a prognostic influence on women.

Effects of isolation-rearing on intracranial self-stimulation reward of the lateral hypothalamus: baseline assessment and drug challenges

There is evidence that isolation rearing produces down-regulation of the dopamine D2 receptor. Therefore, isolation rearing should also modify the effects of D2 antagonists on intracranial self-stimulation (ICSS) reward. This study investigated the effect of isolation rearing on ICSS reward, and modulation of that reward by SCH23390, Raclopride and MK-801. Sprague-Dawley rats were reared alone (isolates) or in pairs from day 21 postnatal to day 75 postnatal. At this time, all rats were implanted with monopolar stimulating electrodes in the lateral hypothalamus. The ICSS rate-frequency curve-shift method was used to assess reward and operant motor function at baseline and after administration of SCH-23390 (D1 antagonist: 0.02, 0.06, 0.2 mg/kg), Raclopride (D2 antagonist: 0.01, 0.025, 0.06 mg/kg), and MK-801 (non-competitive NMDA receptor antagonist: 0.1, 0.2 mk/kg). Isolation-reared rats displayed similar measures of both basal reward and motor function when compared to socially reared controls. Isolation-reared rats were subsensitive to the reward decreasing effects of Raclopride. Socially reared rats were observed to have more variant baseline reward measures, and could be divided into distinctly different groups with different basal reward function. Isolation-rearing down-regulates D2 function but does not affect basal reward function, but some unknown factor in the social rearing environment did have a substantial effect on basal reward function.