Using talking therapies to effectively treat depression in adults over the age of 65 may be clinically linked with slightly reduced rates of future dementia diagnosis, finds a new analysis of health data led by UCL researchers.
In this first-of-its-kind study, published in Psychological Medicine and funded by the Alzheimer’s Society, researchers assessed whether psychological therapies, such as Cognitive Behavioural Therapy (CBT), used to treat depression could play a role in dementia risk reduction.
According to the UCL-led Lancet Commission on dementia prevention, intervention, and care*, approximately 40% of dementia cases may be related to potentially modifiable risk factors. Previous studies have also shown that people with depression during older adulthood may be more likely to subsequently develop dementia.
Researchers examined data from 119,808 people over the age of 65 with clinically significant levels of depression, who had accessed treatment via the national ’Improving Access To Psychological Therapies’ (IAPT) service, between 2012 and 2019.
IAPT is a free NHS service and offers CBT, counselling and guided self-help, with sessions delivered either face-to-face individually or groups or online.
Depressive symptoms were measured using the Patient Health Questionnaire (PHQ-9)**, which considers factors such as a lack of interest in doing things, issues with sleep, and feelings of low mood.
Researchers then linked the IAPT participants’ outcomes (depression scores) with patients’ hospital records for dementia diagnosis. Both data sets were only available for 106,069 people, providing researchers with a study sample.
Data records showed 101,452 of the study sample did not develop dementia at eight years, compared to 4,617 who went onto develop dementia.
In the group who did not develop dementia, researchers found 65% (66,211) had significant improvements in their mental health (depression) following therapy. By comparison, of those who went onto develop dementia, 60.13% (2,776) showed reliable improvement in depression after therapy. Hence, there was lower rates of reliable depression improvement in the dementia group.
Researchers then assessed the difference in dementia rates, between those people who reported improvement in mental health following therapy, with those who saw no improvement.
In total, 68,987 of the study sample had improvements in depression scores, compared to 37,082 who did not see any reliable improvement.
Researchers found in the groups who benefited from therapy and saw reduction in depression, 4% (2,776) developed dementia up to eight years later. By comparison in the group where therapy had no reliable effect, 5% (1,841) went on to develop dementia up to eight years later. Hence, rates of dementia diagnosis were slightly higher in the group who did not reliably improve from psychological therapy.
The study also found that there was a link between the more therapy sessions an older person attended and lower rates of dementia. Researchers believe this could be due to a reduction in depressive symptoms because of engaging in the sessions for longer.
Lead author, Dr Amber John (UCL Psychology & Language Sciences) said: "Depression is an important, potentially modifiable dementia risk factor. However, this is the first study to test and suggest that effectively treating depression in psychological therapies available in the NHS may be linked with slightly reduced future dementia incidence.
"It is important to note that further work is needed to understand whether treating depression with psychological therapies can actually reduce dementia risk.
"Our findings could be due to a second explanation, in that people with underlying dementia, who are not yet diagnosed, may do worse in therapy settings - their depression does not improve - due to emerging cognitive impairment or because therapies are not appropriately tailored to this population. Future research should aim to distinguish between these possibilities."
Previous studies have estimated that 85% of older people with symptoms of depression do not get treatment from the NHS and are five times less likely to access psychological therapies than young people in the UK.
Dr John said: "Older people are currently under-represented in psychological therapy services. These results suggest that increasing access to these services for older people and optimising therapy outcomes may be an important goal for research and policy given they may contribute to dementia risk reduction, as well as being important in and of themselves."
Katherine Gray, Research Communications Manager at Alzheimer’s Society, said: " While previous studies have identified depression as a risk factor for developing dementia , t’his Alzheimer’s Society - funded study is the first to suggest that treating depression through psychological therapies available on the NHS may affect the rates of dementia diagnosis up to eight years later.
"This study has found an association between treatment for depression and dementia risk, another important step forward in researchers’ understanding about how to reduce our risk of developing dementia later on in life. We welcome the Government’s recent pledge to double its annual research spend on dementia and commit an additional £95m investment through the new National Dementia Mission which will help accelerate game-changing research which will transform the lives of thousands of people."
Researchers had no available measure of baseline cognition. It is therefore possible that lack of recovery in psychological therapy may be an early symptom of dementia. It is also possible that participants may have been diagnosed with Mild Cognitive Impairment (MCI) prior to or during therapy, which may have affected therapy progress and outcomes. However, researchers attempted to account for these issues by excluding those who developed dementia within one year of psychological therapy.
Additionally, analyses were limited by the data available in routine collected healthcare records and a majority of the sample were white, with only 4.32% from ethnic minority backgrounds.