Depression is a state of mind any human may undergo at a certain point in time. Moon is the planet which represents our mind and there is a reason why Moon is taken that role. Moon is the fastest moving planet in the Zodiac, Moon goes through different thithis both in waxing and waning states in a very short time of 30 days. So mood changes are part of the Moon and so it is also a major character of a Human Mind.
Now imagine if Moon is stuck in one particular thithi (Lunar Day) for example, Moon starts behaving like a Panchami for all other lunar days. This is something which we see as an abnormal thing. Similarly We human is created to display all the moods but when we fall in love with one single mood, then it is not normal.
Out of all the moods, anger and depression are the self-destructive ones. Ardra or Thiruvaathira is one Nakshatra or Star which is highly capable of amplifying these self-destructive moods in any planet which is posited or transiting it. So whenever a planet and especially Moon is posited in Ardra even a normal person will show some uneasiness.
It is always good if Moon is alone in a house because the conjunction of the Moon with any planet will make that person show affinity towards the moods and character of the planet in conjunction. Shadow planet especially Rahu who likes to impersonate the character of other planets that are in conjunction is very dangerous when it conjuncts with Moon. Because Rahu is a highly focused planet and when its focus is on something that creates addiction, then the person’s mind will fall prey to that and in certain cases goes into dangerous levels of depression.
Ketu is a planet of detachment and spirituality and when in conjunct with Moon, a person if not mentally prepared will fall into confusion about their uncertainty and later can fall into depression.
If Moon is the fastest moving planet, then Saturn is the slowest. When Moon plays with different moods, Saturn is a stubborn one with practical thoughts. In other words, Saturn is just opposite to Moon. When Saturn is in conjunction with Moon a person tends to question themselves about every emotional action, there is no room for fantasy and stories. There is always a fight between the opposites in the Mind. Here if the person’s Moon in the chart is strong, then he/she will be in control and well balanced and sometimes more than anyone else. If Saturn is strong, then it will force Moon to stick to one Mood and if it is a depressed mood, then that is a great problem.
In old days kemadhrum yoga was considered bad and sometimes can create mood swings and depression. But now in this new world where people love to be alone physically and mingle with others virtually, Kemadruma yoga (no planets in the 2nd and 12th house of Moon) is not making any changes.