Bipolar and the Biology Behind
Bipolar disorder is a highly complex psychological condition where the mood swings range from a highly elated manic state to a completely depressed state (Craddock and Jones 1999).It is different from unipolar depression where the episodes of elation are completely zero during the course of illness.
Bipolar Disorder can be of two types.
A)Type -I where a clear cut mania is observed
b) type II where the manic state is rather mild.
Both the types are prevalent across the globe.
This is an equal opportunity disorder affecting anyone regardless of age , caste, gender and ethnicity. According to WHO, bipolar disorder is the sixth leading cause of disability in the world (http://www.bipolar-lives.com/bipolar-disorder-statistics.html).The major cause of death of bipolar disorder patients is suicide. But in addition to this the patients may end up getting cardio and cerebro -vascular diseases, endocrine disorders, and metabolic disorders reducing the span of life to 10-11 tears less than normal individuals. Thus it requires immediate scientific intervention to understand, analyse and verify the cause or causes of bipolar disorder, which largely will be biological, social and even economical in nature. The economical and social causes can be addressed easily once the biological nature of the causes is clear as the response to a particular condition depends largely on your brain's functions.
Many researchers attribute the biological causes of bipolar disorder to a)Genetic factors
b) Problems with the endocrine system and hypothalamus or Brain C)Neuro cognitive malfunction
Many research studies point towards a strong genetic basis for bipolar disorder. The range of rate of concordance of bipolar disorder in identical twins is 40-70%, and the chance of inheritance as per very recent research is 90%( Craddock and Sklar 2013).Bipolar disorder is highly heterogenous in nature(McMohan et al.2010). Other than genetic epistasis structural genomic variations like copy number variants and epigenetic variation are supposed to play a role in the transmission of bipolar disease (Craddock and Sklar 2013, McMohan et al.2010,Lee et al.2011). It is proven that the 66 Val/Met polymorphism of the BDNF gene, associated with the regulation of neural resilience, plasticity, and proliferation, might be the risk gene for bipolar illness.The genes regulate glycogen synthase kinase-3 (GSK-3), a "pro-apoptotic" peptide and a functional "opponent" of proteins involved in neuronal plasticity development, differentiation, and cytoskeletal assembly, are als supposed to play signicant roles in bipolar disorder.
Problems with Brain and other structures
There is also a relationship between the ventricular volume of the brain and BD. There are studies indicating that bipolar illness may be progressive and deleterious, contributing to brain tissue deterioration in the course of recurrent episodes (Brambilla et al.2001).Damage to the interconnected net work of the brain is the major cause for symptoms manifested as emotional, cognitive, behavioural, autonomic, neuroendocrine, immune, and circadian disturbances.( Goldstein et al.2009, Trakowski et al.2012). Prefrontal cortical abnormalities are common in bipolar disorder. Some recent works reported changes in the structure and function of the vmPFC of adolescents and young adult bipolar patients relative to healthy individuals (Blumberg et al.2003, Blumberg et al. 2006).
Beyer and Krishnan(2002) observed that there is a change in hippocampus volume in case of bipolar disorder. Later Blond et al.(2012) verified this. Likewise studies by Blumberg (2005), and blond(2012) point out that the volume of amygdala reflects the presence or progression of bipolar disorder. Blond (2012) confirmed that the changes in amygdale size can indicate a progress in bipolar disorder. The production of automatic emotional responses, including empathy with facial expressions and changes in the function of cerebellum have been linked to cerebellar vermis and has got clinical significance(Maletic 2007).Moreover alterations in the , cerebellar-thalamic-basal ganglia-cortical circuits is supposed to indicate the presence of bipolar disorder.
Neuro cognitive causes
The imbalance in neurotransmitters is very common in Bipolar disorder. The neurotransmitters involved in BD include dopamine, norepinephrine, serotonin, GABA (gamma-aminobutyrate), glutamate, and acetylcholine. The class of neurotransmitter chemicals known as neuropeptides (including endorphins, somatostatin, vasopressin, and oxytocin) also play an important role in both normal and bipolar brains. Reichenberg et al.(2009), point out that 84 % of patients suffering from schizophrenia, 58.3 % of psychotic major depressive patients, and 57.7 % of psychotic BD patients are neurocognitively impaired.
Half of the patients with BD are also having rapid cycling form of BD have hypothyroidism also. So the role of the endocrine system in BD can not be negated. Even the role of reproductive or more specifically ovarian hormones in mood fluctuations can be taken into consideration here. As hypothalamus play an important role in sevretion of hormones , though not confirmed hypothalamus malfunction can be a reason for the onset of bipolar disorder.
Studies by Gualtieri and Morghan (2008) Martino et al. (2008), report that 40 % of BD patients are impaired in one neurocognitive area, one-third or more are impaired in at least two neurocognitive domains and 22 % in three or more domains. Though BD is reported to be associated with high IQ ,a detailed analysis prove that persons with very high and very low IQ are more prone to the disorder (Gale et al.2013)).It is also recorded that the mental processing in BD patients is slow(Seidman et al. 2002).
Bipolar disorder is consuming the globe as a whole due to the swift developments and a conducive environment for the disease to proliferate. Like any other psychological disorder the researchers know that it has a biological cause, and to an extent they could identify it also. But the challenge ahead is to find out the exact cause so that the treatment plan can be effectively chalked out and the progress of the disorder can effectively be controlled. 51 million of the world population is affected by bipolar disorder and waiting for a reason from the scientific community.