Biochemical, metabolic and immune correlates of seasonal variation in violent suicide: a chronoepidemiologic study

Abstract

The purpose of this chronoepidemiologic study was to investigate the time-relationships between the yearly variations in occurrence of violent suicide in Belgium and the yearly variations in various biochemical, metabolic and immune variables in the Belgian population. The weekly mean number of deaths due to violent suicide for all of Belgium for the period 1979-1987 was computed. Twenty-six normal volunteers had monthly blood samplings during one calendar year for assays of plasma L-tryptophan (L-TRP), competing amino acids (CAA), and melatonin levels, maximal [3H]paroxetine binding to platelets, serum total cholesterol, calcium, magnesium, and soluble interleukin-2 receptor concentrations, and number of CD4+ T, CD8+ T and CD20+ B lymphocytes. The annual rhythm in violent suicide rate is highly significantly synchronized with the annual rhythms in L-TRP, [3H]paroxetine binding, cholesterol, calcium, magnesium, CD20+ B cells, and CD4+/CD8+ ratio; the mean peak (violent suicide, [3H]paroxetine binding) or nadir (all other variables) occurs around 3 May. There were significant inverse time-relationships between the time series of violent suicide rate and L-TRP, L-TRP/CAA ratio, total cholesterol, calcium and magnesium, CD4+/CD8+ T cell ratio and number of CD20+ B cells. Maximal [3H]paroxetine binding to platelets was significantly and positively related to the time series of violent suicide. An important part (56.4%) of the variance in mean weekly number of violent suicide rate was explained by the time series of L-TRP, cholesterol and melatonin.

Serum Leptin and Cholesterol Values in Suicide Attempters

“…With respect to diagnostic categories, the relationship was determined in personality and neurotic disorders, depressive disorders and male inpatients with serious suicide attempts [16,17]. However, some authors reported this relationship merely occurring in patients with violent suicide attempts [8]. For this reason, the association between suicide and cholesterol remained subject to controversy.…”

“…In a study by Stewart and Stewart [7] no relationship between cholesterol and aggressive behaviors was found. Maes et al [8] however revealed a relationship between decreased serum cholesterol and suicide attempts only in psychiatric patients with violent suicide attempts.…”

Association of melatonin secretion with seasonal luminosity in human subjects

“…The roles of meteorological and other factors as precipitous agents of suicidal activity have been widely studied. Elevated ambient temperature, low tryptophan availability, increased sunshine duration and low day-time plasma melatonin levels often precede the fatal outcomes (22)(23)(24)(25)(26). As far as melatonin and solar radiation are concerned, previous studies have not been reliable in this respect.…”

Spring snow lowers human melatonin

“…However, neither duration of sunshine nor cloudiness may be reliable indicators of the true amount of the light reaching the eyes, for light reflected off the ground remains underrepresented. Likewise, single daytime measurements (13), common in comparative melatonin studies, represent melatonin secretion poorly.…”