Informant-Based Depression Assessment for Family Members
The Cornell Scale for Depression in Dementia (CSDD) is the best validated informant-based depression questionnaire for family members to complete as collateral information, as it is specifically designed to be administered to both patients and care partners, with the unique advantage that the patient does not need to be able to answer for the scale to be completed 1.
Primary Recommendation: CSDD
The CSDD is a 19-item instrument that stands out among depression scales because:
- It can be completed by the care partner/informant alone when the patient cannot reliably self-report
- Each item is rated on a 3-point scale: 0 = absent, 1 = mild to intermittent, 2 = severe
- Scores range from 0 to 38, with higher scores indicating more severe depressive symptoms
- It is well suited for detecting, tracking progression, and monitoring depression across the severity spectrum from MCI through dementia 1
This makes it particularly valuable when you need collateral information because the patient has cognitive impairment, communication difficulties, or when you want to capture observable behavioral manifestations of depression that the patient may not recognize or report.
Alternative Informant-Based Options
For Broader Behavioral Assessment (Not Depression-Specific)
The Neuropsychiatric Inventory-Questionnaire (NPI-Q) can be completed by family members and assesses:
- 12 neuropsychiatric symptoms including depression
- Both symptom severity (rated 1-3) and caregiver distress (rated 0-5)
- Takes 5-10 minutes to complete
- Publicly available at alz.org 1
Important caveat: The NPI-Q is broader than depression alone and includes agitation, anxiety, apathy, and other behavioral symptoms. Use this when you want comprehensive behavioral information beyond just depression.
Critical Clinical Pitfall
All the commonly cited depression scales (PHQ-9, BDI, CES-D, GDS, HAM-D, HADS) are self-report measures or clinician-administered scales that require patient participation 2. The guidelines explicitly describe these as "self-report scales" that cannot serve as true informant-based collateral instruments 2.
While some scales like the PSWQ-A and GAI "can also be administered to care partner/informant" 1, these are primarily anxiety measures, not depression-specific tools.
When to Use Informant Scales
Deploy informant-based depression assessment when:
- The patient has cognitive impairment (MCI or dementia)
- You suspect the patient is minimizing or unaware of depressive symptoms
- The patient has communication barriers (aphasia, severe illness)
- You need to capture observable behavioral changes (social withdrawal, appetite changes, psychomotor retardation) that family members witness daily
- You want to corroborate self-reported symptoms with external observation
Practical Implementation
- Provide the CSDD to the family member who spends the most time with the patient and has observed them over at least the past week
- Score the 19 items based on the informant's observations of mood, behavioral disturbance, physical signs, cyclic functions, and ideational disturbance
- Interpret scores: Higher scores indicate greater depression severity; scores ≥8 typically warrant clinical intervention
- Combine with patient self-report when possible to get the most complete picture, as research shows informants may underreport internal affective and cognitive symptoms while being more attuned to observable somatic symptoms 3
The CSDD remains the gold standard informant-based depression measure because it was specifically designed and validated for this purpose, unlike other depression scales that were adapted secondarily for informant use.