Jari Jokelainen

Vitamin D supplementation during the first year of life and risk of schizophrenia: A Finnish birth-cohort study

OBJECTIVE Based on clues from epidemiology and animal experiments, low vitamin D during early life has been proposed as a risk factor for schizophrenia. The aim of this study was to explore the association between the use of vitamin D supplements during the first year of life and risk of developing schizophrenia. METHOD Subjects were drawn from the Northern Finland 1966 Birth Cohort (n=9,114). During the first year of life, data were collected about the frequency and dose of vitamin D supplementation. Our primary outcome measures were schizophrenia, psychotic disorders other than schizophrenia, and nonpsychotic disorders as diagnosed by age 31 years. Males and females were examined separately. RESULTS In males, the use of either irregular or regular vitamin D supplements was associated with a reduced risk of schizophrenia (Risk ratio (RR)=0.08, 95% CI 0.01-0.95; RR=0.12, 95% CI 0.02-0.90, respectively) compared with no supplementation. In males, the use of at least 2000 IU of vitamin D was associated with a reduced risk of schizophrenia (RR=0.23, 95% CI 0.06-0.95) compared to those on lower doses. There were no significant associations between either the frequency or dose of vitamin D supplements and (a) schizophrenia in females, nor with (b) nonpsychotic disorder or psychotic disorders other than schizophrenia in either males or females. CONCLUSION Vitamin D supplementation during the first year of life is associated with a reduced risk of schizophrenia in males. Preventing hypovitaminosis D during early life may reduce the incidence of schizophrenia.

Early developmental milestones in adult schizophrenia and other psychoses. A 31-year follow-up of the Northern Finland 1966 Birth Cohort.

Delayed childhood development may precede adult psychoses. We tested this hypothesis in a large, general population birth cohort (n=12058) followed to age 31 years. The ages at which individuals learned to stand, walk, speak, and became potty-trained (bowel control) and dry (bladder control), were recorded at a 1-year examination. Psychiatric outcome was ascertained through linkage to a national hospital discharge register. Cumulative incidence of DSM-III-R schizophrenia, other psychoses and non-psychotic disorders were stratified according to the timing of milestones and compared within the cohort using internal standardization. 100 cases of DSM-III-R schizophrenia, 55 other psychoses, and 315 non-psychotic disorders were identified. The ages at learning to stand, walk and become potty-trained were each related to subsequent incidence of schizophrenia and other psychoses. Compared with the whole cohort, earlier milestones reduced, and later milestones increased, the risk in a linear manner. These developmental effects were not seen for non-psychotic outcomes. The findings support hypotheses regarding psychosis as having a developmental dimension with precursors apparent in early life.

Lifestyle Intervention for Prevention of Type 2 Diabetes in Primary Health Care One-year follow-up of the Finnish National Diabetes Prevention Program (FIN-D2D)

OBJECTIVE To investigate 1-year outcomes of a national diabetes prevention program in Finland. RESEARCH DESIGN AND METHODS Altogether 10,149 individuals at high risk for diabetes were identified with the Finnish Diabetes Risk Score (FINDRISC; scoring ≥15 points), by a history of impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), cardiovascular disease, or gestational diabetes mellitus in 400 primary health care centers. One-year follow-up data were available for 2,798 participants who were nondiabetic at baseline (919 men and 1,879 women, aged 56.0 ± 9.9 and 54.0 ± 10.7 years [mean ± SD] with BMI 30.9 ± 4.6 and 31.6 ± 5.4 kg/m2). RESULTS The incidence of diabetes was 2.0 and 1.2% in men and women with normal glucose tolerance at baseline, 13.5 and 7.4% in those with IFG, and 16.1 and 11.3% in those with IGT, respectively. Altogether 17.5% of the subjects lost ≥5% weight with no sex difference. The relative risk of diabetes was 0.31 (95% CI 0.16–0.59) in the group who lost ≥5% weight, 0.72 (0.46–1.13) in the group who lost 2.5–4.9% weight, and 1.10 (0.77–1.58) in the group who gained ≥2.5% compared with the group who maintained weight. CONCLUSIONS The FIN-D2D was the first national effort to implement the prevention of diabetes in a primary health care setting. Methods for recruiting high-risk subjects were simple and easy to use. Moderate weight loss in this very high-risk group was especially effective in reducing risk of diabetes among those participating in the program.

Psychometric properties of the Finnish 20-item Toronto Alexithymia Scale

The aim of this study was to examine the factor structure and the validity of the Finnish version of the 20-item Toronto Alexithymia Scale (TAS-20). As part of the Northern Finland 1966 Birth Cohort Project, the TAS-20 was presented to a sample of 5034 31-year old persons. A confirmatory factor analysis showed that the three-factor model, earlier established with the original TAS-20, was in agreement with the Finnish version of the scale. Three criteria of goodness-of-fit met the standards for adequacy of fit. For the total scale, internal reliability (Cronbachs alpha) was 0.83 and for the three subscales (factors 1, 2, and 3) it was 0.81, 0.77, and 0.66, respectively. Two- and one-factor models for TAS-20 were also examined, but the other models did not perform as well as the three-factor model. The factor model also worked well with a sample of 516 students with a mean age of 24.8 years. In conclusion, the TAS-20 scale is useful in the Finnish version, too.

Insulin resistance and depression: cross sectional study

A recent study found that depression is inversely associated with insulin resistance, but positively associated with diabetes.1 Association between insulin resistance and depression is a poorly studied area and the few earlier findings do not necessarily support this finding,1 indicating that patients with serious depression have insulin resistance assessed by insulin tolerance, intravenous, or oral glucose tolerance tests.2 Recently, depression was found to be associated with greater insulin resistance in women with polycystic ovary syndrome.3 Also, more than the normal rates of depression had already been noted in patients with clinically manifest diabetes.2 Since insulin resistance is positively associated with the development of diabetes,1 we hypothesised—given that disturbed glucoregulatory functions behind the development of diabetes might be associated with pathophysiological changes in depression2—that insulin resistance should be positively correlated with depressive symptoms. We also investigated whether depressive symptoms varied with different levels of a disturbed glucose metabolism. We invited all 1008 people born …

Cold temperature and low humidity are associated with increased occurrence of respiratory tract infections.

OBJECTIVE The association between cold exposure and acute respiratory tract infections (RTIs) has remained unclear. The study examined whether the development of RTIs is potentiated by cold exposure and lowered humidity in a northern population. METHODS A population study where diagnosed RTI episodes, outdoor temperature and humidity among conscripts (n=892) were analysed. RESULTS Altogether 643 RTI episodes were diagnosed during the follow-up period. Five hundred and ninety-five episodes were upper (URTI) and 87 lower (LRTI) RTIs. The mean average daily temperature preceding any RTIs was -3.7+/-10.6; for URTI and LRTI they were -4.1+/-10.6 degrees C and -1.1+/-10.0 degrees C, respectively. Temperature was associated with common cold (p=0.017), pharyngitis (p=0.011) and LRTI (p=0.048). Absolute humidity was associated with URTI (p<0.001). A 1 degrees C decrease in temperature increased the estimated risk for URTI by 4.3% (p<0.0001), for common cold by 2.1% (p=0.004), for pharyngitis by 2.8% (p=0.019) and for LRTI by 2.1% (p=0.039). A decrease of 1g/m(-3) in absolute humidity increased the estimated risk for URTI by 10.0% (p<0.001) and for pharyngitis by 10.8% (p=0.023). The average outdoor temperature decreased during the preceding three days of the onset of any RTIs, URTI, LRTI or common cold. The temperature for the preceding 14 days also showed a linear decrease for any RTI, URTI or common cold. Absolute humidity decreased linearly during the preceding three days before the onset of common cold, and during the preceding 14 days for all RTIs, common cold and LRTI. CONCLUSIONS Cold temperature and low humidity were associated with increased occurrence of RTIs, and a decrease in temperature and humidity preceded the onset of the infections.

The Association Between C-Reactive Protein Levels and Depression: Results from the Northern Finland 1966 Birth Cohort Study

BACKGROUND To investigate whether depressive episodes (previous, current single, and recurrent) are associated in both genders with highly sensitive C-reactive protein (hs-CRP) levels, earlier recommended for risk assessment of cardiovascular disease. The impact of the severity of current single and recurrent depressive episodes on this putative association was also investigated. METHODS The genetically homogeneous Northern Finland 1966 Birth Cohort was followed until age 31, when, in a cross-sectional setting (n = 5269), the highly sensitive enzyme immunoassay (hs-EIA) method was used to measure CRP concentration. Depressive episodes were defined through mailed questionnaires, including Hopkins Symptom Checklist-25 (HSCL-25) and information on self-reported, doctor-diagnosed depression. RESULTS After adjusting for confounders, logistic regression analyses showed that in male subjects, elevated hs-CRP levels (> or =1.0 mg/L) increased the probability for severe current and recurrent depressive episodes 1.7-fold and 3.1-fold, respectively. Correspondingly, an hs-CRP level of >3.0 mg/L increased the probability for recurrent depression up to 4.1-fold. In female subjects, no statistically significant associations were found. CONCLUSIONS Our results support the hypothesis that an activation of systemic inflammatory processes may contribute to the pathophysiology of severe depression in men. Further investigations are needed regarding the impact of our findings on diagnostic/treatment strategies concerning severe and, especially recurrent, depression in men.

School performance as a predictor of psychiatric hospitalization in adult life. A 28-year follow-up in the Northern Finland 1966 Birth Cohort

BACKGROUND Deterioration in school achievement may pre-date adult mental disorders. We studied the association between compulsory school performance and later onset hospital-treated psychiatric morbidity experienced by the Northern Finland 1966 Birth Cohort (N = 11017) in adult life. METHODS School performance was operationalized in two ways: school class level (in normal, i.e. age-appropriate class v. not in normal class, i.e. class below age level or in special school) at the age of 14, and marks for individual school subjects at the age of 16. School class level was ascertained by postal questionnaire and school marks from national application register. These were linked to data on psychiatric morbidity from the National Finnish Hospital Discharge Register. By the end of 1994 (between ages 16 and 28 years), a total of 383 subjects had psychiatric illness. DSM-III-R diagnoses were grouped into three categories: schizophrenia; other psychoses; and non-psychotic disorders. The remaining population with no psychiatric hospitalization served as a single comparison group. School class level and values of school marks in the three diagnostic categories were each compared with this comparison group, stratified by sex. RESULTS In the comparison group 6.8% of boys and 3.4% of girls were not in their normal class. In all the diagnosis groups the proportions of those not in normal class were from 2 to 8 times higher than in the comparison group. A majority of those not in normal class and having psychiatric diagnosis were intellectually subnormal (IQ < 85). Among adolescents who later developed nonpsychotic disorders, means of school marks were lower (P < 0.05, adjusted for social class and place of residence) than in the comparison group. Lower marks were not found in categories schizophrenia or other psychoses. Logistic regression analysis confirmed these findings after adjustment for confounding factors. CONCLUSIONS Not being in the normal class at age 14 predicted future hospital-treated disorders, but low school marks at age 16 predicted only non-psychotic disorders. These findings may be an early manifestation of the disorders themselves, or a marker of vulnerability or other risk factors. The mechanisms may differ between diagnoses.

Childhood central nervous system infections and risk for schizophrenia

Abstract.Central nervous system (CNS) viral infections have been suggested to increase the risk of schizophrenia, although most of the evidence is indirect and comes from rather few studies on exposure to various infections in general. In the Northern Finland 1966 Birth Cohort the association between schizophrenia and other psychoses and childhood CNS infections has been analysed, and in this paper we present the follow-up results up to the end of 1994 and 1997.Data regarding the infections were collected prospectively between 1966–1980 and data on psychoses from 1982. The registered psychiatric diagnoses were validated using the DSM-III-R classification. Out of the 11017 subjects (96% of all births in that year) 145 had suffered a CNS infection during childhood, which in 102 cases was a viral infection. In the follow-up to the end of 1994, 76 had schizophrenia, and their number increased to 100 to the end of 1997. In addition, up to the end of 1994, 52 patients had a non-schizophrenic psychosis.Four cases in the schizophrenia patient group and none of the patients with other psychosis had suffered a viral CNS infection. None of the schizophrenia cases and two of the patients with other psychosis had had a bacterial infection. The adjusted odds ratio for schizophrenia after a viral CNS infection was 4.8 (95% confidence intervals [CI] 1.6–14.0) in the follow-up to the end of 1994 and 2.5 (0.9–7.0) in the follow-up to the end of 1997. The clinical course variables did not differ between the schizophrenia patients with or without CNS infection.Our results suggest that viral CNS infections during childhood may have a role as a risk factor for schizophrenia. Their role may be modest at the population level due to their relative rareness.

Postchallenge Glucose, A1C, and Fasting Glucose as Predictors of Type 2 Diabetes and Cardiovascular Disease A 10-year prospective cohort study

OBJECTIVE A1C has been proposed as a new indicator for high risk of type 2 diabetes. The long-term predictive power and comparability of elevated A1C with the currently used high-risk indicators remain unclear. We assessed A1C, impaired glucose tolerance (IGT), and impaired fasting glucose (IFG) as predictors of type 2 diabetes and cardiovascular disease (CVD) at 10 years. RESEARCH DESIGN AND METHODS This prospective population-based study of 593 inhabitants from northern Finland, born in 1935, was conducted between 1996 and 2008. An oral glucose tolerance test (OGTT) was conducted at baseline and follow-up, and A1C was determined at baseline. Those with a history of diabetes were excluded from the study. Elevated A1C was defined as 5.7–6.4%. Incident type 2 diabetes was confirmed by two OGTTs. Cardiovascular outcome was measured as incident CVD or CVD mortality. Multivariate log-binomial regression models were used to predict diabetes, CVD, and CVD mortality at 10 years. Receiver operating characteristic curves compared predictive values of A1C, IGT, and IFG. RESULTS Incidence of diabetes during the follow-up was 17.1%. Two of three of the cases of newly diagnosed diabetes were predicted by a raise in ≥1 of the markers. Elevated A1C, IGT, or IFG preceded diabetes in 32.8, 40.6, and 21.9%, respectively. CVD was predicted by an intermediate and diabetic range of 2-h glucose but only by diabetic A1C levels in women. CONCLUSIONS A1C predicted 10-year risk of type 2 diabetes at a range of A1C 5.7–6.4% but CVD only in women at A1C ≥6.5%.