8 New Findings in Bipolar Research

New genes linked with bipolar disorder. Researchers have identified 20 new genetic associations with bipolar disorder. Nine significantly enriched gene sets were revealed, including regulation of insulin secretion and endocannabinoid signaling. Bipolar I disorder was strongly genetically correlated with schizophrenia and driven by psychosis, and bipolar II disorder was more strongly correlated with major depressive disorder. The identification of associated genes may help identify therapeutic targets.

Predominant polarity guides diagnosis and treatment. In an observational study, 28.9% patients with bipolar disorder presented predominant polarity, 17.4% in depressed polarity predominant and 11.5% in manic predominant. There was more rapid cycling in patients who had predominant polarity; illness onset manifested earlier and had a longer duration in those who did not. The authors suggested that considering predominant polarity can help clinicians with their diagnosis and the treatment approach.

Affective temperaments explain life events.Study patients with bipolar disorder and their siblings showed higher scores in cyclothymic and hyperthymic temperaments than controls, with no significant differences in scores of irritable and anxious temperaments. In bipolar patients and siblings, there was a strong relationship between anxious/cyclothymic temperaments and the high number of recent life events. In controls, the number of recent life events was not related to any dimension of affective temperament.

Infliximab does not improve bipolar depression. In a randomized clinical trial of adults who had bipolar I or bipolar II depression and inflammatory conditions, the tumor necrosis factor–antagonist infliximab did not significantly reduce depressive symptoms compared with placebo. However, there was a significant reduction in depressive symptoms with infliximab treatment in those who reported physical or sexual abuse or both.

Psychotic disorder incidence varies by personal characteristics and place. In a review of the incidence of all psychotic disorders, pooled from various studies in several countries, was 26.6 per 100,000 person-years. Men were at higher risk than women for all psychotic disorders and nonaffective disorders but not for affective psychotic disorders. Ethnic minorities were at excess risk for all psychotic disorders. Population registers reported higher rates of nonaffective disorders, schizophrenia, and bipolar disorder than first contact study designs.

Poverty predicts psychosis-spectrum diagnoses. In a study of predictors of psychosis-spectrum disorders in adulthood in urban families, males who were highly aggressive but low on withdrawal were at greater risk for schizophrenia diagnoses. Childhood neighborhood disadvantage predicted both schizophrenia and bipolar diagnoses, regardless of childhood social behavior. The findings suggested universal preventive interventions to help decrease the prevalence of psychosis-spectrum diagnoses.

One is the loneliest number. The prevalence of common mental disorders, including bipolar disorder, is higher in persons who live alone than in those who do not. Living alone was positively associated with common mental disorders regardless of sex or age. Loneliness explained 84% of the living alone-CMD association. Other mediating variables included obesity, smoking status, alcohol dependence, drug use, and social support. Interventions that address loneliness among persons who live alone are suggested.

Kidney issues with lithium. In an assessment of kidney function in patients with bipolar disorder receiving long-term lithium treatment, kidney concentrating ability was significantly decreased. Patients treated with lithium had significantly decreased urine osmolality and urine-to-serum osmolality ratio. No significant difference was found in creatinine, estimated glomerular filtration rate values, and other markers. There were no significant differences between patients treated for 6 to 24 months and those treated for 25 to 240 months.