Purinergic system dysfunctions in subjects with bipolar disorder: A comparative cross-sectional study.

BACKGROUND: Subjects with bipolar mania may have increased uric acid levels, based on a purinergic system dysfunction with reduced neurotransmission of adenosine. We investigated whether there were differences in uric acid levels between individuals with bipolar disorder (in manic or depressive phases) and those with major depressive disorder. METHODS: We conducted a cross-sectional study recruiting 128 subjects with bipolar disorder and 118 with major depressive disorder, admitted to a psychiatric inpatient unit. Standard demographic and clinical information were retrieved from electronic charts and relevant clinical records. Fasting serum values of uric acid, as well as metabolic (total cholesterol, triglycerides, and glycaemia), oxidative stress (albumin, bilirubin), and kidney function (creatinine), parameters, were collected. RESULTS: Subjects with bipolar mania (5.27±1.63mg/dL), but not those with bipolar depression (4.89±1.94mg/dL), had higher levels of serum uric acid (p<0.05), as compared with individuals with major depressive disorder (4.59±1.62mg/dL). Relevant linear regression analyses, controlling for metabolic profile, oxidative stress markers, kidney function, and comorbid alcohol use disorder, showed a significant association between bipolar mania (p<0.01) and increased uric acid. CONCLUSIONS: Findings of this study add evidence to the role of uric acid as state, rather than trait, marker in bipolar disorders. Explored, relevant, confounders do not seem to influence these results. The current study supports the hypothesis of a purinergic system dysfunction associated with manic phases of bipolar disorder.

Association between total serum cholesterol and suicide attempts in subjects with major depressive disorder: Exploring the role of clinical and biochemical confounding factors.

OBJECTIVES: We tested whether serum total cholesterol levels might be associated with recent suicide attempts in subjects with major depressive disorder, after controlling for relevant individual characteristics. DESIGN AND METHODS: We conducted a comparative cross-sectional study including consecutive inpatients with major depressive disorder. We differentiated subjects admitted for a recent serious (violent or non-violent) suicide attempt and those without such recent history. Total cholesterol was measured from fasting blood tests. RESULTS: At univariate analyses, suicide attempters had levels of total cholesterol (174.0±45.7mg/dL) lower than non-attempters (193.9±42.6mg/dL) (p=0.004). This was confirmed among both violent (174.1±46.2mg/dL) and non-violent (173.8±46.1mg/dL) suicide attempters (p=0.035 and 0.016, respectively). However, logistic regression analyses, sequentially including demographic, clinical (comorbid alcohol and personality disorders), and biochemical factors, did not show any association between serum cholesterol and recent suicide attempts (p=0.172). Similar findings were observed in multinomial logistic regression analyses, for both violent (p=0.512) and non-violent (p=0.157) suicide attempts. CONCLUSIONS: Our findings do not support the hypothesis that serum cholesterol and suicide attempts are associated among subjects with major depressive disorder. The identification of valid and accessible biological markers of suicidal behaviors still represents a challenge for future research.