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Adult separation anxiety disorder is likely to be much more common in adults than previously recognized. Research is needed to better understand the relationships of this condition with other co-occurring affective disorders.

The de novo production of steroids and neurosteroids begins in mitochondria by the conversion of cholesterol to pregnenolone through cytochrome P450 side-chain cleavage (CYP11A1) enzymatic activity. The C-terminal amino acid domain of the translocator protein (TSPO) has been demonstrated to bind cholesterol, thereby determining its mitochondrial translocation. The goal of the present study was to investigate the effect of the Ala147Thr single-nucleotide polymorphism localized in this TSPO region on pregnenolone production in healthy volunteers. Pregnenolone production was evaluated in a peripheral cell model, represented by circulating lymphomonocytes. First, CYP11A1 expression, both at mRNA and protein level, was demonstrated. Pregnenolone production varied among genotype groups. Comparison of pregnenolone mean values revealed that Thr147 homozygous or heterozygous individuals had significantly lower pregnenolone levels compared with Ala147 homozygous individuals. These findings suggested a dominant effect of the minor allelic variant Thr147 to produce this first metabolite of the steroidogenesis pathway. Interestingly, Ala147 homozygous individuals exhibited significant higher levels of circulating cholesterol-rich low-density lipoproteins with respect to heterozygous individuals. In conclusion, our results demonstrate that the Ala147Thr spontaneous amino acid substitution within TSPO is able to affect pregnenolone production; this should encourage further studies to investigate its potential role in polygenic dyslipidemias.

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Background: Recent studies indicate that adult separation anxiety disorder is a discrete diagnostic entity and worthy of attention. Previously, we found a significant association between platelet expression of the 18-kDa translocator protein (TSPO) and adult separation anxiety in patients with panic disorder or major depression. The aim of this study was to explore whether adult separation anxiety might be a factor differentiating TSPO expression in a sample of patients with bipolar disorder. Methods: The equilibrium binding parameters of the specific TSPO ligand [³H]PK 11195 were estimated on the platelet membranes of 24 adult outpatients with a DSM-IV diagnosis of bipolar disorder (with or without separation anxiety disorder) and 14 healthy controls. Patients were assessed by SCID-I, HAM-D, YMRS, the Structured Clinical Interview for Separation Anxiety Symptoms (SCI-SAS-A) and the Adult Separation Anxiety Self-Report Checklist (ASA-27). Results: A significant reduction in mean platelet TSPO density was found in bipolar patients with respect to controls. However, the lower density was only evident in the subgroup of bipolar patients who also fulfilled DSM-IV criteria for adult separation anxiety disorder. Individual TSPO density values correlated significantly and negatively with both SCI-SAS-A and ASA-27 total scores. Conclusions: TSPO expression may be a useful biological marker of adult separation anxiety co-occurring with other anxiety and mood disorders, including bipolar disorder.

The current study indicates that EPCs circulate in decreased numbers in ACS patients with depression or anxiety and, therefore, contribute to explore new perspectives in the pathophysiology of the association between cardiovascular disorders and affective disorders.