The psychiatric evaluation is the foundation of all assessment and treatment. This evaluation involves exploration of the symptoms or issues for which psychiatric care is sought. This is often accomplished in the initial clinical interview. A detailed history of the presenting problem is gathered, along with medical and family histories. Assessment questionnaires may also be employed. In some cases the patient may be referred for diagnostic neuropsychological testing. Using a combination of assessment tools, the psychiatrist or psychiatric nurse practitioner arrives at a diagnosis and prescribes appropriate treatment.