Soili M. Lehto

Psychobiotics and the Manipulation of Bacteria–Gut–Brain Signals

Psychobiotics were previously defined as live bacteria (probiotics) which, when ingested, confer mental health benefits through interactions with commensal gut bacteria. We expand this definition to encompass prebiotics, which enhance the growth of beneficial gut bacteria. We review probiotic and prebiotic effects on emotional, cognitive, systemic, and neural variables relevant to health and disease. We discuss gut–brain signalling mechanisms enabling psychobiotic effects, such as metabolite production. Overall, knowledge of how the microbiome responds to exogenous influence remains limited. We tabulate several important research questions and issues, exploration of which will generate both mechanistic insights and facilitate future psychobiotic development. We suggest the definition of psychobiotics be expanded beyond probiotics and prebiotics to include other means of influencing the microbiome.

Stability of alexithymia in the general population: an 11-year follow-up

OBJECTIVES There is an ongoing debate concerning the temporal stability of alexithymia. Most previous studies have been conducted on clinical populations of psychiatric and somatic patients. However, psychiatric and somatic morbidity have been found to confound the findings so that in their presence, alexithymia appears to be less stable. Nevertheless, few general population studies have been published, and there have been no follow-ups longer than 5 years. METHOD In a population-based sample of middle-aged Finnish men, 755 participants completed the Toronto Alexithymia Scale (TAS)-26 at baseline and on 11-year follow-up. Absolute or mean stability refers to the extent to which scores change over time, and it was measured with group comparisons of paired samples. Relative stability refers to the consistency of relative differences in alexithymia levels among the study subjects, and it was measured with test-retest correlations. RESULTS Changes in the total scores and the subscales of the TAS-26 were all statistically significant but had low effect sizes (0.09-0.20) for the change-suggested absolute stability. The correlations between baseline and follow-up scores were high (ρ = 0.51-0.63), indicating relative stability. The exclusion of depressive symptoms, a history of mental illnesses, and cancer or cardiovascular diseases at baseline and at the 4- and 11-year follow-ups did not essentially alter these findings. Of the background variables, a higher age independently associated with the increase in the TAS-26 scores. Those with alexithymia at baseline were more likely to have elevated depressive symptoms at the 4- and 11-year follow-ups. CONCLUSIONS Both the absolute and relative stabilities of alexithymia in the general population are high, even for a long follow-up period. These results may support the assumption that alexithymia represents a stable personality trait in general. Alexithymia may increase vulnerability to depressive symptoms.

Coffee, tea and caffeine intake and the risk of severe depression in middle-aged Finnish men: the Kuopio Ischaemic Heart Disease Risk Factor Study

OBJECTIVE Only a few cross-sectional studies have assessed the association between coffee, tea and caffeine and the risk of depression. Our aim was to determine the association in a population-based cohort study. DESIGN The population-based Kuopio Ischaemic Heart Disease Risk Factor Study cohort was recruited between 1984 and 1989 and followed until the end of 2006. We investigated the association between the intake of coffee, tea and caffeine and depression. SETTING Eastern Finland. SUBJECTS Middle-aged men (n 2232). RESULTS Altogether, forty-nine men received a discharge diagnosis of depression. We classified subjects into quartiles according to their mean daily coffee intake: non-drinkers (n 82), light drinkers (<375 ml/d, n 517), moderate drinkers (375-813 ml/d, n 1243) and heavy drinkers (>813 ml/d, n 390). Heavy drinkers had a decreased risk (RR = 0.28, 95 % CI 0.08, 0.98) for depression when compared with non-drinkers, after adjustment for age and examination years. Further adjustment for socio-economic status, alcohol consumption, smoking, maximal oxygen uptake, BMI and the energy-adjusted daily intakes of folate and PUFA did not attenuate this association (relative risk (RR) = 0.23, 95 % CI 0.06, 0.83). No associations were observed between depression and intake of tea (drinkers v. non-drinkers; RR = 1.19, 95 % CI 0.54, 2.23) or caffeine (highest quartile v. lowest quartile; RR = 0.99, 95 % CI 0.40, 2.45). CONCLUSIONS Coffee consumption may decrease the risk of depression, whereas no association was found for tea and caffeine intake.

Depression is associated with a poorer outcome of lumbar spinal stenosis surgery: a two-year prospective follow-up study.

Study Design. Prospective clinical study. Objective. To investigate the effect of depressive symptoms on the surgery outcome on 2-year follow-up among lumbar spinal stenosis (LSS) patients. Summary of Background Data. Previous research has suggested an association between preoperative depressive symptoms and a poorer surgery outcome among LSS patients. There have been no previous studies on the effect of depressive symptoms on the surgery outcome at the 2-year postoperative phase. Methods. A total of 96 patients (mean age, 62 years) with symptomatic LSS underwent decompressive surgery. They completed the same set of questionnaires before surgery and 3 months, 6 months, 1 year, and 2 years after surgery. Depression was assessed with the 21-item Beck Depression Inventory (BDI). Physical functioning and pain were assessed with the Oswestry Disability Index, the Stucki Questionnaire, self-reported walking ability, he visual analogue scale, and pain drawing. Comparisons were made according to depression status. Logistic regression analysis was used to examine the factors associated with a poorer surgery outcome on 2-year follow-up. Results. After surgery, the patients with continuous depression showed poorer improvement in symptom severity, the disability score, and walking capacity than the patients who did not have depression in any phase. In those patients who recovered from depression, the postoperative improvement resembled that of the constant normal mood group. In regression analyses, an independent association was detected between high preoperative BDI scores and 2-year disability and symptom severity. Strong independent associations were seen between depression burden (the sum of preoperative, 3-month and 6-month BDI scores) and 2-year disability, symptom severity, and poor walking capacity. Conclusion. The patients with a normal mood and those who recovered from depressive symptoms enjoyed the most favorable outcome. Depressive symptoms interfere strongly with the ability of patients to obtain an optimal surgery outcome. Treatment models including the assessment and treatment of depression are encouraged.

Association of depressive symptoms and metabolic syndrome in men

Objective:  To explore the relationship between several indicators of depression and metabolic syndrome (MetS).

Serum adiponectin and resistin levels in major depressive disorder

Lehto SM, Huotari A, Niskanen L, Tolmunen T, Koivumaa‐Honkanen H, Honkalampi K, Ruotsalainen H, Herzig K‐H, Viinamäki H, Hintikka J. Serum adiponectin and resistin levels in major depressive disorder.

Serum chemokine levels in major depressive disorder

OBJECTIVE To examine the role of chemokines of two major chemokine families, CC and CXC, in major depressive disorder (MDD) in a population-based sample. METHOD The serum levels of CC chemokines MCP-1 and MIP-1beta, and CXC chemokine IL-8 were measured from 122 participants (MDD group, n=61; controls, n=61). Depression severity was assessed with the 29-item Hamilton Depression Rating Scale. RESULTS The MDD group had lower levels of MCP-1, MIP-1beta and IL-8 than the healthy controls. The likelihood of major depressive disorder for participants with chemokine levels below the median (MCP-1: < 26.26 pg/mL; MIP-1beta: < 42.57 pg/mL; IL-8: < 2.86 pg/mL) was 3.6 (p=0.002) for MIP-1beta and 2.4 (p=0.037) for IL-8 in regression models adjusted for age, gender, body mass index, smoking, and alcohol consumption. MCP-1 did not associate with the presence of MDD after adjustments for potential confounders. Further adjustments for somatic illnesses or medications did not affect these findings. CONCLUSION Our findings suggest that depression-related alterations of inflammatory markers may be more complex than previously assumed, and that at least some of the chemokines may be down-regulated.

Is alexithymia a risk factor for major depression, personality disorder, or alcohol use disorders? A prospective population-based study

OBJECTIVE Disagreements concerning the stability of alexithymia and its ability to predict subsequent psychiatric disorders prevail. The aim of this 7-year follow-up study was to examine whether alexithymia predicts subsequent major depression, personality disorder, or alcohol use disorders in a population-based sample. METHODS The four-phase Kuopio Depression Study (KUDEP) was conducted in the eastern part of Central Finland. The study population (aged 25-64, n=2050) was randomly selected from the National Population Register. Data were collected in 1998, 1999, and 2001. In 2005, a subsample (n=333, 43 were excluded) of the 3-year follow-up population (1998-2001) was gathered and their diagnoses of mental disorders were confirmed by the Structure Clinical Interview for DSM-IV Axis I (SCID-I). Alexithymia was measured using the Toronto Alexithymia Scale (TAS-20) and depressive symptoms using the Beck Depression Inventory (BDI-21). For both of these measures, two groups were formed based on the median of their sum score (summing the 1998, 1999, and 2001 scores). Logistic regression analyses were performed. RESULTS BDI sum scores, but not those of TAS, were associated with subsequent major depressive disorder, personality disorder, and alcohol use disorders in 2005. The BDI sum scores explained 35.7% of the variation in concurrent TAS sum scores. CONCLUSION Alexithymia did not predict diagnoses of major depressive disorder, personality disorder, or alcohol use disorders. Alexithymia was closely linked to concurrent depressive symptoms. Thus, depressive symptoms may act as a mediator between alexithymia and psychiatric morbidity.

Fear of childbirth predicts postpartum depression: A population-based analysis of 511 422 singleton births in Finland

Objectives To study how reproductive risks and perinatal outcomes are associated with postpartum depression treated in specialised healthcare defined according to the International Classification of Diseases (ICD)-10 codes, separately among women with and without a history of depression. Design A retrospective population-based case–control study. Setting Data gathered from three national health registers for the years 2002−2010. Participants All singleton births (n=511 422) in Finland. Primary outcome measures Prevalence of postpartum depression and the risk factors associated with it. Results In total, 0.3% (1438 of 511 422) of women experienced postpartum depression, the prevalence being 0.1% (431 of 511 422) in women without and 5.3% (1007 of 18 888) in women with a history of depression. After adjustment for possible covariates, a history of depression was found to be the strongest risk factor for postpartum depression. Other strong predisposing factors for postpartum depression were fear of childbirth, caesarean birth, nulliparity and major congenital anomaly. Specifically, among the 30% of women with postpartum depression but without a history of depression, postpartum depression was shown to be associated with fear of childbirth (adjusted OR (aOR 2.71, 95% CI 1.98 to 3.71), caesarean birth (aOR 1.38, 95% CI 1.08 to 1.77), preterm birth (aOR 1.65, 95% CI 1.08 to 2.56) and major congenital anomaly (aOR 1.67, 95% CI 1.15 to 2.42), compared with women with no postpartum depression and no history of depression. Conclusions A history of depression was found to be the most important predisposing factor of postpartum depression. Women without previous episodes of depression were at an increased risk of postpartum depression if adverse events occurred during the course of pregnancy, especially if they showed physician-diagnosed fear of childbirth.

Alexithymia is associated with increased cardiovascular mortality in middle-aged Finnish men.

Objective: To explore the associations between alexithymia and increased somatic morbidity. The mechanisms underlying these associations, however, are still unclear. Furthermore, data on the association between alexithymia and mortality are scarce. Methods: A total of 2321 Finnish men, aged 46 to 61 years, were followed up for an average of 20 years. Mortality rates were obtained from the national register. The associations between baseline alexithymia and cardiovascular disease (CVD), all-cause, injury, and cancer deaths were examined with adjustments for age and several behavioral (smoking, alcohol consumption, physical activity), physiological (low- and high-density lipoprotein cholesterol, body mass index, systolic blood pressure, history of CVD), and psychosocial (marital status, education, depression) factors. Results: After all adjustments, the risk of CVD death was increased by 1.2% for each 1-point increase in Toronto Alexithymia Scale-26 scores. Conclusions: Alexithymia is associated with increased cardiovascular mortality. BDI = Beck Depression Inventory; BMI = body mass index; CI = confidence interval; CVD = cardiovascular disease; HDL-C = high-density lipoprotein cholesterol; HPL Depression Scale = Human Population Laboratory Depression Scale; LDL-C = low-density lipoprotein cholesterol; RR = risk ratio; TAS = Toronto Alexithymia Scale.