Bipolar Disorder as a Mental Illness - Article Example

Empirical evidence suggests an association between BD and an altered hypothalamic-pituitary-adrenal (HPA) axis. A study by Colasanti, Owen, and Grozeva, et al. (2013) investigates this association further by looking at the impaired function of the HPA axis caused by cholesterol metabolism. The basis of this study is an association between the deregulation of the HPA axis and BD diagnosis, present in all clinical cases of BD.

Dysfunction of the HPA axis may be caused by an alteration in the rate-limiting step of cortisol metabolism. A mitochondrial membrane translocator protein (TSPO) is a key regulator in this pathway as it limits the translocation of cholesterol into the powerhouse (Colasanti, Owen, & Grozeva, et al., 2013). An amino acid substitution polymorphism (rs 6971) in the gene encoding for this transporter protein greatly affects the affinity of TSPO to cholesterol. This altered affinity in the defective protein in turn impairs the metabolism of steroids including those of the HPA axis.

This study provides evidence of an association between a single nucleotide polymorphism in the TSPO gene and the diagnosis of bipolar disorder in a large-scale case-control study (Colasanti, Owen, & Grozeva, et al., 2013). However, the results of this study are suggestive as the findings did not reach genome-wide significance; though they were reproducible. This nominal association suggests the possible existence of other confounding factors in the etiopathogenesis of bipolar disorder. A limitation of this study is the use of imputation in the analysis of the rs6971 SNP in the TSPO gene.

In conclusion, bipolar disorder is a mental illness characterized by mood swings. There are several environmental and genetic etiologies to this condition, which can progress to severe forms such as psychosis. A study by Colasanti, Owen, and Grozeva, et al., suggests a possible genetically altered HPA axis function as a causative factor in BD. The genetic mutation in the mitochondrial translocator protein (TSPO) impairs the metabolism of neurosteroids, which in turn alters the HPA axis function (Colasanti, Owen, & Grozeva, et al., 2013). Read More