Panic Disorder can be preceded by overwhelm.
Here is the typical sequence from which many initial panic attacks are derived:
Anxiety can often strike us when we feel overwhelmed. Especially if we are unaware of steadily increasing stressors.
When unaware of our stress load and lacking healthy coping methods, a strong adrenaline surge can follow - that old "fight or flight" experience. For many when this happens, unless one has the proper skills to handle it, a panic attack can follow.
If not handled quickly with awareness and specific strategies, more panic attacks can follow leading to Panic Disorder.
Panic Disorder is defined by at least a month of recurring unexpected panic attacks with a fear of having more, tendency to avoid situations or experiences where panic attacks have occurred leading to a lack of freedom, and an extreme concern about what the panic attacks might imply or result in (ex. loss of control, sanity, death).
The good news is none of the above has to happen if you are familiar with how to handle anxiety and those adrenaline surges - in addition to your stress level.
Follow this link for more on anxiety treatment for Panic Disorder