The depressive mind works differently than that of a healthier person; the biochemistry is different. The ‘balanced chemistry’ in a healthy mind gives way to imbalances that puzzle and perplex the ill-affected. Neurochemicals like dopamine, serotonin, or norepinephrine, crucial for mood stabilization, are not found in the same regions nor abundances the brain of those suffering from depression.

Neurochemical Receptors

Before the advent of computational chemistry, the standard understanding of ‘neurochemical receptors’ forced the medical community to throw anything that sticks at the problem. The results were oftentimes mixed and tragic. However, the recent biochemical and medical research paint nuances of depressive disorders that may sound surprising to the layman.

Subtleties of the chemical structures of anti-depressant drugs point towards a more convoluted biochemistry. To a brain, no single anti-depressant drug is identical, and researchers understood that modern anti-depressants fell into three neurochemical categories: serotonin targets, norepinephrine targets, and dopamine targets. The generalities of depression corresponded to a spectrum of despair, confusion, sadness, and physical lethargy, and a unique anti-depressant drug could treat different aspects within the range of depression.

The Case of Prozac

The serotonin targets, relatively new, were introduced in the late 1980s with Prozac. The makers of Prozac promised miracles, but soon enough, their hopes faded when it appeared that not everyone responded to the drug in the same manner. A distinguishing feature of the Prozac debacle was that early on (in the 1990s) certain groups suffered deepening depressions as a result of taking the miracle drug.

The shocking revelation, however, delineates the roles of how medicinals play in miss-shaping brain receptors. While the drug Prozac works primarily on the serotonin receptors of pleasure and well-being, the depression may be centered on dopamine, which is a different type biochemical receptor. When a drug like Prozac is administered, it will mal-adapt to the Dopamine receptor and change its shape. Once the receptor is miss-shapen, the correct drug takes longer to adapt to the receptor.

Maladaptive Molecules and the Truth of Depressive States

Each modern anti-depressant seeks out its corresponding receptor in the brain. However, in cases where you are taking an anti-depressant that does not fit the proper receptor—it is like you are trying to put a square peg into a round hole. The fit is not exact; the receptor becomes misshapen (although the drug gives a little respite from the illness). Because anti-depressants are not identical, the concept of maladaptive molecules (drugs) lend a new insight of how anti-depressants work.

The brain consists of tissue that shuttles electrical impulses back and forth; it is the electrical impulses that contain vital information on one’s well-being, knowledge, movements, and bodily functions. The electrical impulses leave neurochemicals in their wake that seek to fill in the gaps of where the impulses originated. In cases of depression, you may feel lethargic, ill-feelings, or sadness as a result of these nuerochemicals. In simple terms, lethargy corresponds to an overabundance of dopamine, feelings of illness correspond to a lack of norepinephrine, and feeling sadness corresponds to a lack of serotonin.

The question of where are these neurochemicals reside in the brain falls into how neuroscientists recognize depression. In the cases of serotonin and norepinephrine, researchers believe that there are an over-abundance of serotonin and norepinephrine receptors—whisking away the feel-good chemicals (serotonin and norepinephrine). In the case of dopamine, there aren’t enough receptors to bind the over-abundance of dopamine. In this case, you’ll end up feeling and acting lethargic – without energy or motivation.

Genetic Tendencies Determine Depression

If you probe deeply into the source of these neurochemicals, you’ll notice that there are genetic tendencies for the biochemical imbalances. The affected chromosomes seem, to the layperson, like an random mix of affected sites. In reality, however, biochemical markers on your chromosomes determine whether depression may lurk in your future. By marking out the precise chromosome location, modern research and medicine will learn to target the ill-affected with laser-like precision and hopefully reduce tragic outcomes.

This article originally appeared in Decoded Science, on 11 January 2015.