TITLE:
Etiology and Diagnosis of Major Depression—A Novel Quantitative Approach
AUTHORS:
Johnny T. Ottesen
KEYWORDS:
Depression; HPA-Axis; Etiology; Diagnoses; Clustering Analysis; Mixture Effect Modeling
JOURNAL NAME:
Open Journal of Endocrine and Metabolic Diseases,
Vol.3 No.2,
May
23,
2013
ABSTRACT:
Background: Classical psychiatric opinions are relative uncertain
and treatment results are not impressive when dealing with major depression.
Depression is related to the endocrine system, but despite much effort a good
quantitative measure for characterizing depression has not yet emerged. Methods: Based on ACTH and cortisol levels and using clustering analysis and mixture
effect modeling we propose a novel and scientifically based quantitative index,
denoted the O-index. The O-index combines a weighted and scaled deviation from
normal values in both ACTH and
cortisol. Results: Using ANOVA we compare the O-index with opinions reach by classical
psychiatric diagnostic procedure (sensitivity 83%, specificity 59%, likelihood
ratio positive 2.0, and likelihood ratio negative 0.29). The O-index nicely
refines the etiology of depression: Combined with clinical data for 29 subjects
earlier reported three categories emerge (p = 4.4 × 10-13): hypocortisolemic depressed,
non-depressed, and hypercotisolemic depressed. The O-index also reveals why it
has been difficult to obtain good markers earlier. It explains that healthy
subjects may have an elevated (suppressed) level of cortisol or ACTH, however, the healthy system is
able to deal with such elevated (suppressed) levels by compensating through
suppressing (stimulating) the other component. In contrast the O-index shows
that depressed subjects are incapable of making such compensation to a
satisfactory degree. We illustrate how the O-index may be used for diagnostic
procedure. Discussion: The methods
are discussed and based on the available data material we propose that the
O-index may be used to improve the diagnostic procedure and consequently the
follow-up treatment.