Reductions in platelet 18-kDa translocator protein density are associated with adult separation anxiety in patients with bipolar disorder.
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 [(3)H]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.
Department of Psychiatry, Neurobiology, Pharmacology and Biotechnology, University of Pisa, Pisa, Italy.
Marianna
M
Abelli
Beatrice
B
Chelli
Barbara
B
Costa
Lisa
L
Lari
Alessandra
A
Cardini
Camilla
C
Gesi
Matteo
M
Muti
Antonio
A
Lucacchini
Claudia
C
Martini
Giovanni B
GB
Cassano
Stefano
S
Pini
D000328:Adult; D001010:Anxiety, Separation / Q000097:blood* / Q000150:complications*; D001714:Bipolar Disorder / Q000150:complications*; D001792:Blood Platelets / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007546:Isoquinolines / Q000378:metabolism; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011485:Protein Binding / Q000502:physiology; D011569:Psychiatric Status Rating Scales; D018079:Receptors, GABA / Q000097:blood*; D018709:Statistics, Nonparametric; D014316:Tritium / Q000378:metabolism
D007546:Isoquinolines; D018079:Receptors, GABA; C499229:TSPO protein, human; D014316:Tritium; C037850:PK 11195