Both in the field of Mental Health, and the public's perception of that field, the word depression is a much misused word and a misunderstood concept.

The verb "to depress" literally means, in the context of this usage, to "make despondent, deject, lower or reduce, whilst the noun "depression" means "a state of extreme dejection". In the context of this discussion the quality which is depressed, thereby creating the condition of depression, is the patient's mood state, a concept which will be discussed below. However in order to fully appreciate the true nature of depression it must be clearly understood from the outset of the discussion that depression of mood may be abnormal, leading to a depressive illness, or normal, leading to that quality of mind that is generally referred to as sadness or unhappiness, or in a special situation of loss, grief. However both forms of depressed mood can exist at the same time, thus producing a complicated interaction between them, although, where depression is severe, it will so totally overwhelm the normal operations of human mood as to make the experiencing of both normal happiness and normal unhappiness impossible.

In normal every day experience the human mind functions in may different ways, two of the most important being that it thinks, involving the management of ideas and concepts, and it feels, involving the experience of emotions. There are many different and complex emotional states that human beings commonly feel and some of these may be described with words such as unhappiness, or sadness, two words which probably have a very similar, if not precisely similar, meaning, grief, a special form of unhappiness in the face of a loss, anxiety, fear, boredom, frustration, resentment, and anger. All of these are normal states of mind, although they may frequently be held in a way that can could be seen as somewhat inappropriate by a level headed average observer who might see a particular person as being angry to a degree that is inappropriate the apparent nature of the events producing that anger. Nevertheless in these circumstances the observer would still recognise the essential normality of the anger itself, and would require only a greater degree of provocation to feel that same degree of anger themselves. Human beings may experience these emotions in relatively pure form, but more commonly they are present as a combination of two or more of the individual emotions. However unfortunately in common usage today any individual suffering from such an emotion, or a combination of any these emotions, is referred to, and tends to refer to themselves, as depressed.

This common usage of the word gives rise to two major problems, firstly it is remarkably non specific, there is after all a great difference between an angry and frustrated person and a grief stricken one, but more importantly it fails completely to address the issue of the essential normality of these feeling states, and of the associated fact that behind them lies normal brain chemistry. In contrast true depression represents a state of abnormal brain chemistry, about the nature of which a certain amount is now known, and is therefore an abnormal state of mind, and not merely the extension of any of the previously discussed normal states of mind.

Unhappiness is the emotion felt by normal human beings, under essentially normal if unfortunate circumstances when aspects of their lives, either past or present, are not as they would wish them to be, and it contrasts with the state of mind of happiness, which exists and is experienced when a person's external life, again either past or present, is experienced particularly pleasing. These two emotional states lie at opposite ends of a spectrum of human experience that, using the word properly and correctly, is called mood. A normal mood state therefore lies anywhere on the spectrum of experience between manifest happiness and great sadness, with the majority of human beings being perhaps for the majority of their life in an essentially neutral mood state that is appropriate to the events of a life that is in general acceptable, but not necessary productive of ecstatic happiness or great sadness. Under the ebb and flow of life events therefore feelings will move appropriately on the mood spectrum according to the impact of those life events.

Mood in this sense is an extremely important part of the human adaptation to the external world, and in particular to our relationship with other human beings in that external environment. Essentially it functions in a similar, but more complex, manner to experiences such as hunger and thirst and pain. If we do not feel hunger we do not eat, and if we do not eat, we starve to death. If we do not feel thirst we do not drink, and if we do not drink we die of dehydration. If we do not feel pain we leave our hands on red hot barbecue plates and suffer severe injuries. In a similar manner if we do not feel appropriately sad or happy then we do not respond to the outside world in an appropriate fashion. Normally therefore the external world creates the appropriate mood state, which then leads us in turn to react appropriately to that external world, the reaction for happiness being to so behave as to preserve those features of the outside world which are making us happy, and the reaction to unhappiness being to resolve whatever problems are generating the sadness. In the case of unhappiness there are dual mechanisms which can be utilised, difficulties may exist in the external world and be necessarily therefore resolved in the external world, such as problems within the marriage or one's workplace, or they may exist internally, as in the case of the special form of sadness, called grief, that is felt for the death of a loved one, which clearly cannot be put right externally by bringing that loved one back to life, and must therefore be resolved internally by a process known as grieving.

Whichever method of dealing with the sadness is appropriate, and it may well be a combination of those methods, once the cause of the sadness has been dealt with it is possible to return to a normal mood state, and, if the subsequent course of life is favourable, to again experience true happiness. It is this purpose of normal mood states that makes any attempt to deal with the pain of unhappiness by the use of drugs, whether medical or non medical, socially acceptable or unacceptable, legal or illegal, entirely inappropriate and an invitation to personal disaster, as such an approach to unhappiness is truly equivalent to a person who is starving to death, suppressing their hunger pains with amphetamines in the presence of an abundant supply of food. As clearly the appropriate response in this case is to follow the promptings of one's hunger and meet one's driving need for food, so as the appropriate response to unhappiness is to follow the prompting of that unhappiness and deal with the causes of the emotional state rather than attempt to suppress the emotional state itself with drugs.

There is not a lot of knowledge as to how, or where, in the human brain the mechanisms of mood operate, although more is being learned about these complex events every year. Nevertheless it is reasonable to argue that common observation shows that such mechanisms do exist in human behaviour, and that for them to exist the human brain must be capable of certain basic operations. Firstly it must be able to contain some idea of a reasonable expectation from life, which can be thought of as equivalent to the par score for a golf course. Secondly it must be able to correctly assess the nature of current and past events, and thirdly it must be able to assign an appropriate score to those events. Having done these things it must then compare the par score and the current score and produce an appropriate response, which is happiness if the current score is greater than par and unhappiness if the current score is less than par. Finally of course it must enter into the complex procedures necessary to respond appropriately to the feeling state in terms of behaviour.

Whilst our knowledge of these mechanisms is relatively limited we have far greater knowledge of a different function of the human brain, which can serve as an excellent model through which it is possible to understand the true nature of depression. Human beings, like all mammals, maintain a constant body temperature, and, since this is a very basic bodily function, it is possible, unlike complex issues of happiness and sadness, to study this legitimately and effectively in other animals and transfer the results directly to humans. As a result it is known that the brain controls the body temperature by what is known as a feedback loop. Essentially a small part of the brain contains the knowledge that the appropriate temperature for the human body under normal circumstances is thirty seven degree centigrade, a further part of the brain literally measures the temperature of the blood flowing through it, and a third part compares these two temperatures. As long as the two temperatures are similar the person feels comfortable, and neither excessively hot or cold.

However if they are placed in a situation of extreme cold their actual body temperature will inevitably begin to fall, and as this occurs a gap will appear between the standard temperature, of thirty seven degree centigrade, and the actual measured body temperature. Before this gap is more than a matter of a fraction of a degree certain events will occur as a consequence of its existence. Firstly the person will feel cold and their behaviour will change in that they will exercise, put on clothes or light fires. Secondly their body will react automatically to the falling temperature, and amongst other events their skin blood vessels will be shut down to conserve heat, and they will begin to shiver to generate extra heat. Providing the cold stress is not too great the net effect of these responses will be to return their body temperature to thirty seven degrees centigrade, at which point they will again feel comfortable. These events therefore provide us with a good model of normal lowering of the mind, in that in the case of the operation of one's mood regulating mechanism one is rendered sad, or uncomfortable, by events, responds to those events, and, providing the response is effective, thereby resolve the sadness and again become comfortable. In the case of temperature regulation one becomes uncomfortable as a result of a falling body temperature, and regains comfort when that falling body temperature is restored to normal.

Thirty seven degrees centigrade is the temperature of the human body only under normal conditions, and it may vary when conditions are abnormal, most commonly in the presence of infection. One of the effects of some infections is to cause an immediate, and marked, change in the body temperature. In effect the body's thermostat is readjusted from a setting of thirty seven degree centigrade to one of perhaps forty degrees centigrade. When this occurs it creates an immediate gap of three degrees centigrade between the actual body temperature and the measured body temperature. In practice however the brain is unable to distinguish between a gap created by changing the actual body temperature whilst keeping the expected body temperature unchanged, and a gap created, in the same direction, by keeping the actual body temperature unchanged and changing the expected body temperature.

In these circumstances therefore the person, now usually a patient, feels extremely cold, in practice far colder than one usually ever feels on exposure to extreme cold stress as such, and they endure an experience which is known as a rigor. During this their teeth chatter, they are totally miserable with cold, and they will beg those nursing them to pile ever increasing layers of blankets over them in an attempt to get warm. In practice of course what is happening is that their body temperature is being driven up to the new expected temperature of forty degrees centigrade, and when that temperature is achieved they feel a sudden sense of profound relief and a return of comfort in the sense of their perception of their body temperature, however they still remain feeling less than well as there are other effects of the infection. During the entire process those nursing them will have had a different experience of events, even without the use of a thermometer they will have been aware that the patient's body temperature is in fact far higher than usual, and rising progressively.

There is therefore a complete separation between the actual nature of the patient's body temperature and their experience of that temperature. If when undergoing a rigor a particular patient happens to be possessed of a vast amount of knowledge as to the mechanisms of temperature regulation in the human body, and assuming that unfortunate individual is still capable of thinking reasonably clearly, he or she will be aware of the nature of the process, and will therefore know in the thinking part of their mind that they are much hotter than usual, knowledge which might not be available for a less well informed person in the same circumstances, but knowledge which will not lead to them feeling in any way any warmer as a result of its possession. It is at this point of understanding that we can leave the issue of temperature regulation and return to the topic of depression.

In unhappiness we have said that the feeling state is produced by the mind recognising that actual events in the outside world are less favourable to the person than they expect from an average experience of life, in other words it is the result of their measured experience falling below their expected experience. True depression exists when there is a gap in a similar direction between the experience and the expected measured experience, but where this gap is created not by a change in the external world, but by a change in the internal world by which the expectations of the mind become unreasonably inflated, in contrast to which expectation the ordinary experiences of life, whether better than average, uneventful, or somewhat worse than average, may appear irredeemably black and hopeless, just as a normal body temperature of thirty seven degrees is experienced as being abnormally cold in comparison to the expectation of a body temperature of forty degrees centigrade created by the presence of a severe infection.

Lying behind this change in the setting of the mood regulator is a literal chemical change in the brain, about which an increasing amount is now known, that involves chemical messengers known as neuro-transmitters. The result of this chemical change is not confined simply to the mood state, but is also reflected in changes in many other aspects of the workings of both the mind and the body. Thus the truly depressed patient may be not only in a lowered mood state, possibly to the point of being at serious risk of suicide, but may also be excessively anxious, or angry and irritable, or any combination of these various states of mind, as well as experiencing changes in their sleep patterns, appetite, sex drive, memory and power of concentration.

The processes underlying a normally working mood mechanism therefore are that the external world, in the form of both past and present events, determines the mood state, which then leads to an appropriate response to those circumstances, which in the case of happiness is to behave in such a way as to attempt to preserve those circumstances and in the case of unhappiness is to modify them, either by manipulation of the external world or by an internal process of grieving. In the case of true depression however the abnormal mood state is produced internally, the consequence being inappropriate reactions to the external world, and the level of distortion of the person's experience of that world may be so great as to lead them to suicide, an act, which, if understood within the context of their totally distorted view of the world in which they live, is essentially logical.

At the same time there are changes in the generalised functioning of that person's body. Their sleep commonly becomes disturbed, as does their appetite, to a degree that can produce a profound weight loss, their memory and concentration are frequently impaired, their sexual drive and interest lowered, and, if the process becomes intense enough, they may even begin to have totally abnormal experiences, experiencing hallucinations, that is sensations, such as hearing voices, that have no external source, and become profoundly convinced of their own unworthiness and the essential total hopelessness of the world. Finally they may increasingly lose what has been an "insight", that is the ability to recognise at an intellectual level the inappropriateness of their feelings.

In summary then unhappiness is a normal lowering of the mood, which exists in a brain whose chemical functioning is normal, and which must be managed by an appropriate response to the events creating the unhappiness, and in which the use of drugs of any kind is usually undesirable. In contrast depression is an abnormal lowering of the mood, where there is a clear chemical abnormality in the state of the brain, and is therefore, in the final analysis, essentially a physical illness, which may be severe enough to lead to suicide and thus can be truly seen as a potentially fatal illness, and the appropriate use of modern medical drugs, known as antidepressants, is therefore not only appropriate but vitally necessary in its proper management.

Article contributed by: Dr. Chris Percival, Psychiatrist, Shepparton, Victoria, Australia.

Milton Sofoulis Sr, Dip.B.S., Dip.Min(Hon), Dip. Prof.Couns., is a professional counsellor based in Deniliquin, NSW, who specialises in relationship counselling, stress management, self esteem, and for general personal issues.

He is available for personal counselling, group counselling, interactive discussion groups, corporate presentations, and presentations for special interest groups.

Phone/Fax: (03) 5881 2581. Mobile: 0438 812 581. .