Adult attention-deficit/hyperactivity disorder (ADHD) represents a significant public health burden. ADHD is often comorbid with many other psychiatric disorders, with a high co-occurrence with depression. However, there is a paucity in our understanding of the potential impact of treating patients' ADHD on their depressive symptoms. The primary objective of this study was to assess the effect of treating adult ADHD on comorbid depressive symptoms without directly administering treatment for depression in an integrated behavioral health clinic in the primary care setting. We performed a retrospective chart review between April 2021 and May 2022 on adult patients treated in the Primary Care Adult Integrated Behavioral Health Clinic at an urban family medicine residency clinic. For patients with ADHD, we administered the Adult ADHD Self-Report Scale (ASRS-v1.1) to serve as a marker of ADHD symptom burden and the nine-item Patient Health Questionnaire(PHQ-9) to serve as a marker of depressive symptom burden. We administered the questionnaires prior to initiating ADHD treatment and again at the three-month follow-up visit. The ADHD treatment included pharmacotherapy and brief psychological interventions targeted at ADHD. We compared the ASRS scores and PHQ-9 scores at baseline and after three months to determine whether ADHD treatment had any impact on PHQ-9 scores. At baseline, the average ASRS score was 11.3 and the average PHQ-9 score was 8.25. Comparing scores after three months of intervention to the initial scores, our preliminary results demonstrated a trend of improvement in both ASRS and PHQ-9 scores. A total of 75% (n=24/32) of the patients had an improvement in ASRS scores, and 56.7% (n=17/30) of the patients had an improvement in PHQ-9 scores at three months. At three months, there was a decline in PHQ-9 scores with a decrease in ASRS scores following treatment. Our preliminary results suggest that integrated behavioral health treatment of ADHD using a combination of pharmacological and non-pharmacological interventions may play a role in improving comorbid depressive symptoms.