Immune system markers may predict affective disorder treatment response, but whether an overall immune system marker predicts bipolar disorder treatment effect is unclear.

Bipolar CHOICE (N = 482) and LiTMUS (N = 283) were similar comparative effectiveness trials treating patients with bipolar disorder for 24 weeks with four different treatment arms (standard-dose lithium, quetiapine, moderate-dose lithium plus optimised personalised treatment (OPT) and OPT without lithium). We performed secondary mixed effects linear regression analyses adjusted for age, gender, smoking and body mass index to investigate relationships between pre-treatment white blood cell (WBC) levels and clinical global impression scale (CGI) response.

Compared to participants with WBC counts of 4.5–10 × 109/l, participants with WBC < 4.5 or WBC ≥ 10 showed similar improvement within each specific treatment arm and in gender-stratified analyses.

An overall immune system marker did not predict differential treatment response to four different treatment approaches for bipolar disorder all lasting 24 weeks.

Immunological theories, particularly the sickness syndrome theory, may explain psychopathology in mood disorders. However, no clinical trials have investigated the association between overall immune system markers with a wide range of specific symptoms including potential gender differences.

We included two similar clinical trials, the lithium treatment moderate-dose use study and clinical and health outcomes initiatives in comparative effectiveness for bipolar disorder study, enrolling 765 participants with bipolar disorder. At study entry, white blood cell (WBC) count was measured and psychopathology assessed with the Montgomery and Aasberg depression rating scale (MADRS). We performed analysis of variance and linear regression analyses to investigate the relationship between the deviation from the median WBC, and multinomial regression analysis between different WBC levels. All analyses were performed gender-specific and adjusted for age, body mass index, smoking, race, and somatic diseases.

The overall MADRS score increased significantly for each 1.0×109/l deviation from the median WBC among 322 men (coefficient=1.10; 95% CI=0.32–1.89; p=0.006), but not among 443 women (coefficient=0.56; 95% CI=−0.19–1.31; p=0.14). Among men, WBC deviations were associated with increased severity of sadness, inner tension, reduced sleep, reduced appetite, concentration difficulties, inability to feel, and suicidal thoughts. Among women, WBC deviations were associated with increased severity of reduced appetite, concentration difficulties, lassitude, inability to feel, and pessimistic thoughts. Both higher and lower WBC levels were associated with increased severity of several specific symptoms.

Immune system alterations were associated with increased severity of specific mood symptoms, particularly among men. Our results support the sickness syndrome theory, but furthermore emphasise the relevance to study immune suppression in bipolar disorder. Due to the explorative nature and cross-sectional design, future studies need to confirm these findings.

Helmet use among bike-share users is low. We sought to characterize helmet-use patterns, barriers to helmet use, and cycling safety practices among bike-share users in Toronto.

A standardized survey of public bike-share program (PBSP) users at semi-random distribution of PBSP stations was undertaken. By maintaining a ratio of one helmet-wearer (HW): two non-helmet-wearers (NHW) per survey period, we controlled for location, day, time, and weather.

Surveys were completed on 545 (180 HW, 365 NHW) unique users at 48/80 PBSP locations, from November 2012 to August 2013. More females wore helmets (F: 41.1%, M: 30.9%, p=0.0423). NHWs were slightly younger than HWs (NHW mean age 34.4 years vs HW 37.3, p=0.0018). The groups did not differ by employment status, education, or income.

Helmet ownership was lower among NHWs (NHW: 62.4% vs HW: 99.4%, p<0.0001), as was personal bike ownership (NHW: 65.8%, vs HW: 78.3%, p=0.0026). NHWs were less likely to always wear a helmet on personal bikes (NHW: 22.2% vs HW: 66.7%, p<0.0001), and less likely to wear a helmet always or most of the time on PBSP (NHW: 5.8% vs HW: 92.3%, p<0.0001). Both groups, but more HWs, had planned to use PBSP when leaving their houses (HW: 97.2% vs NHW: 85.2%, p<0.0001), primarily to get to work (HW: 88.3% vs NHW: 84.1%, p=0.19). NHWs were more likely to report that they would wear a helmet more (NHW: 61.4% vs HW: 13.9%, p<0.0001), and/or cycle less (NHW: 22.5% vs HW: 4.4%) if helmet use was mandatory.

PBSP users surveyed appear to make deliberate decisions regarding helmet use. NHWs tended to be male, slightly younger, and less likely to use helmets on their personal bikes. As Toronto cyclists who do not wear helmets on PBSP generally do not wear helmets on their personal bikes, interventions to increase helmet use should target both personal and bike-share users. Legislating helmet use and provision of rental helmets could improve helmet use among bike-share users, but our results suggest some risk of reduced cycling with legislation.