I am sure you are wondering what pizza has to do with mental health. It is much more than enjoying a tasty slice or two. A slice of pizza represents a part of a whole and introduces us to the concept of systems theory. The systems concept helps us process a lot of information in a more orderly way, to be able to go back and forth between the whole and its parts, understanding the interaction between the forest and its trees. We can examine the individual trees while at the same time taking in the picture of the entire forest. One’s mental health represents the forest. The goal of this paper is to better understand the trees, the critical systems that contribute to the whole of our emotional being. We are all aware of the nature versus nurture approach. To what degree can we explain a person’s psychological makeup on genes (nature) or upbringing and life experience (nurture)? I wish it was that simple, just a matter of measuring the degree to which nature and/or nurture matter so we can then direct treatment proportionally to each factor. How does one measure the effect of a problematic childhood or stressful life events? How to quantify the brain-based source of bipolar disorder or schizophrenia? Mental health professionals have some tools to provide these measurements but they are extraordinarily rudimentary. Our technology in not yet at the level to allow for definitive answers. A general systems approach helps us address the biological, psychological and social fields that ultimately contribute to our wellbeing or ill mental health. The biological field consists of not just our brain but the body systems that ultimately influence brain function such as the cardiovascular, endocrine, pulmonary and gastrointestinal. As an example, chronic obstructive pulmonary disease (COPD) can reduce the availability of oxygen to the brain and consequently alter brain function. A simple experiment decades ago demonstrated that the use of a portable oxygen generator can significantly increase the IQ of a person suffering from COPD. This same individual would subsequently experience less depression and emotional duress. Or the individual on a variety of sedating medications that erroneously creates a clinical picture of memory deficits masquerading as a dementia. Additionally, if one has a medical disorder that will be lifelong, how do we anticipate the psychological toll it will take on the person in the future? Addressing these concerns become an essential part of the treatment team. The social systems are a bit more difficult to assess due to the subjective nature of data gathering. Family of origin influences are paramount. Negative influences can be mollified by the presence of healthy role models and support systems when young. Interpersonal relations represent an important influence on self concept development. Only recently have we begun to recognize the impact of childhood bullying on the psyche. The goal of a reasonably healthy childhood is to produce a person whose self regard and image is based on their own uniqueness, not necessarily on being good looking, a star athlete, rich of top of their class. This healthy self concept serves as the foundation for the acquisition of future skill, talents and attributes. To further complicate the impact of social systems on mental health we have to add a time dimension to our study that includes the past, present and the future. A person who comes out of a pathological family of origin can then be exposed to corrective emotional experiences in the present (like good friends and role models) that help dilute the damage already done. Likewise, emerging from a healthy childhood only to be currently traumatized in battle can result in enduring psychological difficulties like post traumatic stress disorder. We must also pay attention to the individual’s expectations of the future. Do they look forward with a cup is half empty approach or with a cup is half full attitude? Are they on a life path that will help ensure future stability (like a career, education, marriage, etc.) or are they proceeding towards the future with limited or confused goals and plans? Or, have they been influenced to pursue a career by their family that they really had no say in and find themselves trapped and helpless? These are several examples of the data that must be gathered by mental health professionals. Psychological systems are not as easily assessed because they represent concepts that must be deduced and not so easily observed or measured. They include attitudes, belief systems and coping styles. They are the product of one’s journey through childhood and later life representing an ongoing learning process, for good of for bad, a process that can be adaptive or maladaptive for healthy growth. When maladaptive traits are significantly pervasive and persistently interfere with function we raise the clinical possibility of a character or personality disorder. The veracity of this diagnosis is important because treatment of personality disorders can be quite difficult and protracted. Once we gather systems data it is now necessary to develop a treatment plan. How to determine where to direct treatment? If someone presents with depression, is it adequate to prescribe an antidepressant alone and offer no other treatment recommendations? This is where the systems approach becomes essential. For example, treating the depression alone without attending to address the presence of significant marital discord in an individual with childhood trauma will not result in the desired outcome unless the other areas of dysfunction are addressed. Sometimes it is necessary to create a stepwise approach. Let us assume that the individual with depression is so depressed that full participation in psychotherapy would be unproductive until the depression begins to improve. In this case it would be important to improve the depression with medication before proceeding with psychotherapy. As I have discussed in past articles it is a challenge to determine if a person’s current symptoms represent a brain-based biological disorder or a reaction to a life situation. We know that all behavior, thought processes and emotional expression emanates from our brains but the difference between a biological disorder and a life reactive state is that the former tends to be long-lasting and persistent while the latter tends to be time-limited. It is important to recognize that there is a middle ground between the biological and the situational states disorders is best described as a hybrid state. The hybrid state occurs when an individual with a biological (possibly genetic) predisposition to depression, anxiety or psychotic disorders interacts with a stressful life situation. The biological predisposition is then activated and resulting in a pathological disorder. Our pizza pie model of mental healthcare would not be complete without a discussion about the importance of assembling a team of professionals to provide both evaluation and treatment. The ideal team is composed of multidisciplinary licensed mental health professionals with multimodality evaluation and treatment capabilities. The ability to provide a comprehensive psychological test battery, perform a focused psychological trauma assessment or obtain a medical neuropsychiatric evaluation makes it possible to identify which slices of our pizza pie need to be addressed in the treatment plan. Most importantly, the presence of this team under one roof allows for ongoing treatment meetings and consultations among the professionals. Being able to share clinical information in realtime is essential to the management of complex mental health problems. Teamwork also provides mutual support for the clinicians and promotes professional growth.