Age-Related Differences in Autobiographical Memory Functioning After Electroconvulsive Therapy in Patients with a Major Depressive Disorder

Electroconvulsive therapy (ECT) is considered the most effective treatment for severe major depressive disorder (UK ECT Review Group, 2003; Sienaert, 2011), even after inadequate response to both pharmacological and psychological therapies (Weiner & Reti, 2017). ECT is particularly effective among older adults (Dols, 2017; van Diermen, 2018), with high remission rates ranging from 50% to 70% (Dols, 2017; Haq et al., 2015; Oudega et al., 2011). Importantly, current research has found no evidence that ECT causes brain damage in adults aged 18 years and older diagnosed with major depressive disorder (Gbyl & Videbech, 2018), nor has it been shown to increase the risk of developing dementia later in life (Hjerrild et al., 2021). Despite its proven clinical efficacy, the use of ECT remains limited, primarily due to concerns about (transient) cognitive side effects, which continue to represent a significant issue even with the implementation of modern ECT techniques (Ingram, 2008; Andrade et al., 2016; Porter et al., 2020). ECT may lead to cognitive side effects in several domains (Semkovska et al., 2010; Verwijk et al., 2012; Kumar et al., 2016) and are generally classified into the following categories: postictal confusion (occurring immediately after a session), anterograde amnesia (emerging during the course of treatment), retrograde amnesia (appearing during and after the treatment course), and impairments in non-memory domains such as attention and executive functioning. Fortunately, in patients with late-life depression, ECT has not been found to produce long term adverse effects on attention, executive functioning, or anterograde memory six months after the course of ECT (Obbels & Verwijk, 2018). However, age appears to systematically influence cognitive outcomes: younger patients may be more vulnerable to short-term side effects, such as reduced verbal fluency and memory retention (Loef et al., 2024). Among the cognitive side effects of ECT, autobiographical memory loss (the inability to recall personally experienced past events) is one of the adverse effects that greatly concerns patients (Rose et al., 2003), due to its fundamental role in preserving identity, maintaining a sense of self-continuity (Wilson & Ross, 2003) and strengthening social bonds (Bluck & Alea, 2002). A recent systematic review and meta-analysis by Mathiassen et al. (2025) integrated findings from nine longitudinal studies and confirmed that ECT leads to a moderate impairment in autobiographical memory, as compared to non-ECT-treated controls. Interestingly, higher age was correlated with smaller memory loss, though the mechanisms remain unclear and outcome may be attributable to floor effects or differences in baseline cognitive performance. Importantly, the study found that memory loss did not improve at long-term follow-up (6–12 months), indicating a potential persistence of these impairments. Other treatment-related factors, such as ECT electrode placement (Mathiassen et al., 2025), pulse width (Sackheim et al., 2008), and stimulus intensity/dosing parameters (Sackheim et al., 2000) have been linked to cognitive outcomes. However, age-related differences in cognitive outcomes have not yet been systematically investigated in relation to these parameters. However, older adults were underrepresented in prior studies, despite being the main recipients of ECT. This underrepresentation highlights a crucial gap in understanding whether age affects autobiographical memory outcomes following ECT. Addressing this gap is particularly important because depression and cognitive decline frequently coexist in older adults, yet ECT remains a vital treatment option for this population. To accurately assess autobiographical memory during the course of ECT, the use of standardized and validated instruments is essential. The Kopelman Autobiographical Memory Interview (Kopelman-AMI; Kopelman et al., 1989) is a well-established and broadly validated interview for evaluating autobiographical memory in dementia and neurological syndromes, but it was not designed to measure the consistency of recall over time, which is the primary complaint of patients after ECT. To address this limitation, the Columbia University Autobiographical Memory Interview (CUAMI; Semkovska, Noone, Carton, & McLoughlin, 2012) and later its short form (CUAMI-SF; Sackheim, 2014) were developed to quantify autobiographical amnesia by assessing the consistency of memories relative to baseline (Semkovska, Noone, Carton, & McLoughlin, 2012). This provides a direct measure of how much patients’ autobiographical memories change or deteriorate relative to their own baseline. Inspired by the CUAMI, consistency scores will also be calculated for the Kopelman-AMI in the present study in order to evaluate changes in autobiographical recall over time. An important advantage of the Kopelman-AMI is that it allows for the assessment of change in autobiographical memory in both directions, capturing not only autobiographical memory loss, but also potential improvement over time. This is particularly relevant for patients experiencing a depressive episode, as retrieval difficulties may occur that lead to reduced access to autobiographical memories. Because these retrieval problems can improve with clinical recovery, the Kopelman-AMI offers a valuable opportunity to access not only memory impairment, but also recovery-related improvements in autobiographical memory over the course of ECT. Against this background, the present study aims to examine whether autobiographical memory performance after ECT varies across age in patients with major depressive disorder. Using the Kopelman Autobiographical Memory Interview, the study aims to examine whether the amount of autobiographical memory loss is associated with age. Both traditional autobiographical memory scores and the consistency of recalled memories will be considered. Based on previous literature, we expect that autobiographical memory declines following ECT, but that higher age is associated with relatively smaller loss (Mathiassen et al., 2025).