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 g...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.展开更多
A class of n-dimensional ODEs with up to n feedbacks from the n’th variable is analysed. The feedbacks are represented by non-specific, bounded, non-negative C<sup>1</sup> functions. The main result is th...A class of n-dimensional ODEs with up to n feedbacks from the n’th variable is analysed. The feedbacks are represented by non-specific, bounded, non-negative C<sup>1</sup> functions. The main result is the formulation and proof of an easily applicable criterion for existence of a globally stable fixed point of the system. The proof relies on the contraction mapping theorem. Applications of this type of systems are numerous in biology, e.g., models of the hypothalamic-pituitary-adrenal axis and testosterone secretion. Some results important for modelling are: 1) Existence of an attractive trapping region. This is a bounded set with non-negative elements where solutions cannot escape. All solutions are shown to converge to a “minimal” trapping region. 2) At least one fixed point exists. 3) Sufficient criteria for a unique fixed point are formulated. One case where this is fulfilled is when the feedbacks are negative.展开更多
文摘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.
文摘A class of n-dimensional ODEs with up to n feedbacks from the n’th variable is analysed. The feedbacks are represented by non-specific, bounded, non-negative C<sup>1</sup> functions. The main result is the formulation and proof of an easily applicable criterion for existence of a globally stable fixed point of the system. The proof relies on the contraction mapping theorem. Applications of this type of systems are numerous in biology, e.g., models of the hypothalamic-pituitary-adrenal axis and testosterone secretion. Some results important for modelling are: 1) Existence of an attractive trapping region. This is a bounded set with non-negative elements where solutions cannot escape. All solutions are shown to converge to a “minimal” trapping region. 2) At least one fixed point exists. 3) Sufficient criteria for a unique fixed point are formulated. One case where this is fulfilled is when the feedbacks are negative.
