A nurse is assessing a patient who has been diagnosed with a major depressive disorder (MDD). The patient reports feelings of hopelessness, persistent sadness, and a lack of interest in previously enjoyed activities such as gardening and reading. The nurse notes that the patient has also experienced significant weight changes and sleep disturbances over the past few months. In the context of mood disorders, the nurse recognizes that these symptoms may indicate the presence of two key elements often used to classify depressive episodes.

Please fill in the blanks: In major depressive disorder, the two key symptoms typically include ______________ and ______________.