Preliminary Efficacy Trial of a Digital Intervention for Depression and Cannabis Use

Change in Depressive Symptoms (Patient Health Questionnaire-9; PHQ-9)

Depressive symptoms will be measured with the Patient Health Questionnaire-9 (PHQ-9). The PHQ-9 is a widely-used 9-item self-report measure that assesses depressive symptom severity over the previous two weeks. Scores on the PHQ-9 range from 0-27, with greater scores indicating greater depression severity.

Change in Cannabis Use Frequency (Daily Sessions, Frequency, Age of Onset, and Quantity of Cannabis Use Inventory; DFAQ-CU)

Cannabis use use will be measured with the Daily Sessions, Frequency, Age of Onset, and Quantity of Cannabis Use Inventory (DFAQ-CU). The DFAQ-CU is a 24-item self-report measure that assesses frequency, age of onset, and quantity of cannabis use. There are six factors: daily sessions, frequency, age of onset, marijuana quantity, concentrate quantity, and edible quantity. The six factors, except age of onset, are independently scored, and higher scores indicate greater cannabis use. Our primary outcome will assess changes in frequency.

Usability (System Usability Scale; SUS)

The System Usability Scale (SUS) is a 10-item self-report measure commonly used to assess the degree to which participants endorse ease of use following task-based operation of computer systems (i.e., perceived usability). Total scores on the SUS range from 0 to 100, with greater scores indicating greater usability. An average score of 68 or greater on the SUS in our AMP-C group will indicate acceptable usability.

Feasibility (Engagement)

Feasibility will be measured through the number of modules completed for the AMP-C group.

Intervention Feasibility (App Usage)

Feasibility will be measured through app usage time (hours).

Change in Daily Depressive Symptoms (Mobile Patient Health Questionnaire-9; MPHQ-9)

Daily depressive symptoms will be measured with the Mobile Patient Health Questionnaire-9 (MPHQ-9). The MPHQ-9 is a modified version of the paper PHQ-9, which has been used in intensive sampling studies. Participants answer questions regarding their experience with the nine symptoms of MDD over the past 24 hours on a sliding scale. Total scores range from 0-900, with greater scores representing greater depression severity.

Changes in Daily Cannabis Use

Daily cannabis use will be measured with a series of questions related to cannabis use consumption. These questions will capture frequency, quantity, product types, potencies, and administration methods of cannabis over the past 24 hours.

Change in Alcohol Use (Drinking Motives Questionnaire-Revised; DMQR)

Reasons for drinking alcohol will be measured with the Drinking Motives Questionnaire-Revised (DMQR). The DMQR is a 20-item self-report measure that assesses common reasons for why people might drink alcohol. There are four subscales: Social, Coping, Enhancement, and Conformity. Subscale scores range from 1-25, with greater scores representing greater endorsement of specific reasons for drinking alcohol.

Change in Substance Use (Timeline Followback; TLFB)

Broader substance use will be measured with the Timeline Followback (TLFB). The TLFB is a self-report measure that assesses substance use and related behaviors over the past 30 days. Participants will be asked to identify the number of days over the 30 days in which they have consumed alcohol, tobacco/nicotine, opioids, stimulants, hallucinogens, sedatives/depressives, inhalants, and other illicit or prescription drugs. Total scores are not calculated, but the outcomes of interest include number of days per substance, with greater scores indicating a higher number of days of substance use in the past 30 days.

Change in Anxiety Symptoms (Generalized Anxiety Disorder-7; GAD-7)

Anxiety symptoms will be measured with the Generalized Anxiety Disorder-7 (GAD-7). The GAD-7 is a 7-item self-report measure that assesses anxiety symptom severity over the previous two weeks. Total scores range from 0-21, with higher scores representing higher anxiety severity.

Change in Fear of Happiness (Fear of Happiness Scale; FHS)

The Fear of Happiness Scale (FHS) is a 9-item self-report measure that assesses fear and apprehension of positivity due to its association with negative outcomes. Total scores range from 0-36, with greater scores representing greater fear of happiness.