Diagnosing depression in people with dementia has long posed a challenge for clinicians.
Many of the emotional, cognitive, and behavioural symptoms used to identify depression can also be direct consequences of neurodegenerative disease itself. Now, clinician‑researchers at UQ’s Queensland Brain Institute (QBI) have developed a new tool designed to more accurately screen for depression in people with dementia.
Professor Peter Nestor and Dr Joshua Flavell have developed and validated a dementia-specific version of the Geriatric Depression Scale (GDS), one of the most widely used depression screening tools in older people worldwide.
Professor Nestor explained that the new 10‑item screening tool is designed to detect depression in people living with dementia by removing questions known to be confounded by cognitive impairment and apathy.
“The challenge isn’t recognising depression, it’s distinguishing it accurately from dementia,” Professor Nestor said.
“Some questions on standard screening tests ask about symptoms like memory problems, loss of motivation, or feeling pessimistic about the future, which can be caused by the dementia, even if the person is not depressed.
“This work grew directly out of our clinical experience. Dr Flavell and I see people with dementia and mood symptoms every week, and existing depression scales are not fit for purpose in this population group. Conventional screening tools can over-diagnose depression by misinterpreting symptoms in people with dementia.”
Psychiatrist Dr Flavell agreed. “We see people with dementia labelled as depressed when, in fact, they were responding honestly to questions that were really asking about their dementia,” he said.
“We reviewed the original 30‑item GDS and removed items likely to be influenced by cognitive impairment, apathy, somatic symptoms (physical symptoms linked to mental health conditions) or existential concerns.
“The remaining set of questions in the new tool, GDS-D, focused squarely on depressed mood and anhedonia (the reduced ability to feel pleasure).”
The team retrospectively analysed data from 82 patients assessed at specialist memory and psychiatric clinics, including people with Alzheimer’s disease, frontotemporal dementia, and primary depressive disorders. All participants had undergone gold‑standard psychiatric assessment using DSM‑5 criteria – globally recognised guidelines used by psychiatrists to diagnose mental health conditions.
The results showed the GDS‑D demonstrated diagnostic accuracy of 92-97 per cent, outperforming the original 30‑item scale and all commonly used shorter versions. Importantly, it was far less likely to misclassify people with dementia as depressed.
While the researchers describe the findings as preliminary, they say the GDS‑D shows strong promise as a practical screening tool for memory clinics and specialist settings.
“The GDS-D better aligns with how clinicians actually diagnose depression in people with dementia,” Dr Flavell said.
Professor Nestor said larger studies are needed to confirm its effectiveness across broader dementia populations.
“For patients and families, getting the diagnosis right and in a timely manner matters enormously,” said Professor Nestor. “This screening tool will help identify people with dementia who need further evaluation more accurately and quickly.”
This research is published in the Journal of Affective Disorders
