Depression as The Reason of Serious Health Problems and Suicide

With an aging global population, depression in the elderly is emerging as a serious public health concern. At present it is estimated that nearly 8%-16% of the elderly (aged > 65) living in the community suffers from clinically significant depressive symptoms1, an indicator of significant morbidity and early mortality2. According to the World Health Organization (WHO), it is also the most important precursor of suicide and will be the second cause of Global Disease Burden by the year 2020.

The overall prevalence of depression is 9%, of major depressive episode is 36%, and the average age of onset of depression is 31.9 years, in India.3. Older age of a depressed patient is a significant predictor of an unfavourable course with an increased risk of relapse3, reduced likelihood of treatment response4,5 and diminished chance of functional recovery6. Furthermore, the emergence of treatment resistant depression (TRD) is common among the elderly, with an estimated rate between 26 and 41 per 100 people per years7.

Randomised Controlled Trials (RCTs) of antidepressants reveal a smaller size of treatment effect among the elderly compared to the younger age groups5. This difference may be related to the differences in the pathophysiology and phenomenology of depression among older people. Inaccurate assessment and incorrect diagnosis of depression in its early stages can also prevent the effective care of individuals with depression. Having been recognized as a multifactorial disease, the total contribution of genetic factors in the origin of disease, the heritability, is estimated at nearly 40%8. Thus, relevant DNA sequence variations in potential candidate genes contributing to the susceptibility to depression remain to be explored. Numerous studies have reported the involvement of abnormal gene expression or single nucleotide polymorphisms (SNPs) of neurotransmitter genes in the development of depression9.

Neurotransmitters (NA) are chemical messengers which conduct signals from one nerve cell to another. They play a central role in the pathophysiology of brain disorders, thus are targets for pharmacological treatments. Many recent studies have shown that reduced levels of neurotransmitters at the synapse underlie depression or mood disorders10. Dysfunction in dopaminergic neurotransmission has also been suggested in the pathophysiology of depression. Several studies consequently reported that the plasma levels of the dopamine metabolite (HVA) were lower in depressed patients11.

In contrast, suicide victims without a history of depression have normal levels of HVA, dopamine, and NA, based on the results of some autopsy studies12. Neurotransmitters play an integral role in these disease states; therefore they are the prime targets for treating disorders of the nervous system and mental health concerns. In view of the pressing need to prevent mental disorders in Geriatric Population and to elucidate the genetic basis for mental illness and its complications; and with increasing understanding of impact of genetic variability on the development of mental illness current case control study is designed.It will give us a better understanding of the origin and pathogenesis of this complication.

Furthermore, it will improve our knowledge of inter-individual variation in the development and progression of depression; in a clinical setting, mapping and identification of genes that regulate neurotransmitter levels offer the prospect of identifying novel molecules that can serve as targets for drug design in the search for new treatments for mental illness. Another potential application of genetics is in the field of diagnostics i.e. the genetic markers once established can be used to predispose the individuals who are at high risk for the causation of the mental illness.