Threshold and subthreshold bipolar disorders in the Sesto Fiorentino Study.
BACKGROUND
The DSM IV lifetime prevalence for bipolar affective disorders is reported to be between 0.4% and 1% in most surveys. DSM IV, however, fails to identify the cases clinically significant described as bipolar spectrum. The few researches that have attempted to evaluate the prevalence of these disorders in the community report lifetime prevalence figures of 5% to 10% for the whole spectrum.


METHODS
The data from the Sesto Fiorentino Study, a community survey conducted by clinical interviewers using a typically clinical instrument, have been re-analysed. 2363 people out of the 2500 randomly selected in order to be representatives of the population aged 14 or more living in Sesto Fiorentino (44,000 inhabitants, Central Italy) could be evaluated according to a two-phase design.


RESULTS
The lifetime prevalence rates were 0.47% for bipolar I disorder, 0.38% for bipolar II (0.85% for DSM IV bipolar disorders). A much greater number of subjects had clinically significant hypomanic symptoms that failed to fully satisfy the diagnostic criteria, totalling to 4.66% of the population. Compared with depressives without any sign of bipolarity (N=297), these "subthreshold bipolar" cases had significantly greater comorbidity for Generalised Anxiety Disorder, Obsessive-Compulsive Disorders and Anorexia Nervosa, as well as with Obsessive-Compulsive Passive-Aggressive, Paranoid, Borderline personality disorders. Their depressive symptom pattern cases differed from that of the "pure" unipolar cases for a significantly greater frequency of psychic agitation, psychotic symptoms and hyperphagia.


CONCLUSIONS
The main limitation of the study is its retrospective nature, whereas it confirms the clinical relevance of even softer forms of bipolarity on epidemiological grounds.
Faravelli
Carlo
C
Department of Neurology and Psychiatry and Department of Psychology, Florence University, Italy. carlo.faravelli@unifi.it
Rosi
Simone
S
Alessandra Scarpato
Maria
M
Lampronti
Lorenzo
L
Amedei
Silvia Gorini
SG
Rana
Nusrat
N
D000328:Adult; D000856:Anorexia Nervosa / Q000175:diagnosis / Q000453:epidemiology; D001008:Anxiety Disorders / Q000175:diagnosis / Q000453:epidemiology; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology*; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology; D003937:Diagnosis, Differential; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D007558:Italy; D008297:Male; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis / Q000453:epidemiology; D010554:Personality Disorders / Q000175:diagnosis / Q000453:epidemiology; D012189:Retrospective Studies