Memory decline and depression in older adults: Is it a chicken and egg question or can we identify a directional relationship?

Older adults often report memory problems even when cognitive testing is normal. A new analysis in BMC Geriatrics shows that healthcare providers should take note of these memory complaints as they can predict later depressive symptoms. In this blog post, the authors of this study explain how they reached this finding and what it means.

As people grow older, they may experience changes in their memory, like forgetting an appointment or someone’s name, leading to concerns about their memory functioning. And older adults sometimes report having memory problems despite performing normally on memory tests, such as those conducted by their doctor. Even if cognitive testing is normal, subjective memory complaints are important to consider as they might be an early indicator of more serious problems with memory and cognition or psychological stress such as depression or anxiety. Older adults can have memory complaints as well as typical symptoms of depression, making it difficult for healthcare providers to determine how these symptoms are related. It is unclear from the current research whether, in older adults with both depressive symptoms and memory complaints, depressive symptoms lead to problems with memory or whether the perception of memory problems contributes to the development of depressive symptoms.

To better understand the order in which memory complaints and depressive symptoms occur, we need to see how these two symptoms develop within an individual over time. In our new study, published in BMC Geriatrics, we examine the development of depressive symptoms and memory complaints in two large groups of older adults across periods of 6-18 years.

What we did

Perceiving that their memory is getting worse may lead an older adult to experience symptoms of depression.

We used two large, publicly available datasets that together represented over 10,000 older adults from across the United States. These longitudinal datasets included measures of memory complaints and depressive symptoms, collected via interviews conducted every year or every other year for up to 18 years. Any older adult experiencing clinically significant changes in their cognition was removed from our study. This is important because individuals with cognitive impairment may not report memory complaints due to a lack of awareness of their memory problems.

Older adults reported their perceptions of their memory in two questions, one for current memory rating and one for memory decline over the past year or two years. The first question asked for a rating of their memory at the present time. A second question then asked whether they perceived their memory to be better, worse, or the same as it was the last time they were interviewed. For depressive symptoms, older adults indicated whether they had recently experienced a range of symptoms e.g., felt down, depressed or hopeless. We controlled for other personal characteristics that might influence depressive symptoms and/or memory complaints such as sex, education level, age, race/ethnicity, income, and marital status.

What we found

We first examined whether memory complaints co-occurred with depressive symptoms. That is, at times when a person reported a memory complaint, did they report more depressive symptoms? In one of the two datasets, we found that at times when an older adult provided lower current memory ratings, they also reported more depressive symptoms. Importantly, we also found that at times when an older adult reported a decline in memory, they also reported more depressive symptoms at that same interview across both datasets.

We then examined whether memory complaints predicted future depressive symptoms. We found that older adults’ rating of their current memory at one interview was not related to their depressive symptoms at the next interview. However, when an older adult reported a decline in memory at one interview, they reported more symptoms of depression at the next interview across both datasets. Interestingly, this was not true in the other direction: current symptoms of depression did not predict future memory complaints.

What it means

Helping older adults understand normal changes in memory could prevent increases in depressive symptoms.

Memory complaints are often seen as a symptom of depression in older adults; however, our work suggests that this is not the case for all types of memory complaints. Older adults’ low rating of their memory performance can be related to depressive symptoms, but is not always. In contrast, older adults’ feeling of their memory getting worse over longer periods of time (e.g., a year or two) is consistently related to their current feelings of sadness and hopelessness as well as to increases in future depressive symptoms. Therefore, perceiving that their memory is getting worse may lead an older adult to experience symptoms of depression. This may be because when an older adult feels like their memory is getting worse, they start to experience sadness or hopelessness about their memory, and what it means to grow older in general. Alternatively, for some older adults, perceiving that their memory is getting worse could also trigger fears about dementia or other aging-related disorders. It likely depends on the individual and their different experiences with aging and memory.

Clinical implications

Health care professionals working with older adults should consider asking them about how their memory is changing over time. These types of questions are necessary to understand how an older adult is currently feeling, but are also important for how they may be feeling at future appointments. This suggests that helping older adults understand normal changes in memory could prevent increases in depressive symptoms and promote better psychological health and well-being.

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