Late-Life Depression

This project focuses on clinical translational research into personalized transcranial alternating current stimulation (tACS) for treating anhedonia in late-life depression (LLD). Key components include: (1) Optimizing individualized tACS treatment parameters through randomized, double-blind, controlled trials and establishing precise treatment protocols using deep learning algorithms; (2) Assessing the short-term (2 weeks) and long-term (3 months) efficacy of tACS on depressive symptoms and anhedonia using scales such as the HAMD, SHAPS, and DARS, while monitoring safety; (3) Integrating multimodal detection technologies (64-channel EEG, inflammatory factors/neurotransmitters, etc.) to elucidate the mechanisms by which tACS alleviates anhedonia through modulating prefrontal neural oscillations (y-band), improving synaptic plasticity (increased BDNF), and regulating neurotransmitters (5-HT, DA). This study will establish, for the first time, an individualized parameter system for tACS treatment of LLD, providing a novel non-pharmacological intervention strategy for clinical practice.

The aim of this clinical trial is to investigate the effects of L-serine supplementation on cognitive decline and psychosocial functioning in older adults with late-life depression (LLD). The study will evaluate changes in depressive symptoms, neural and cognitive functioning, and will assess neurophysiological, metagenomic, and biochemical alterations associated with L-serine supplementation compared with placebo. The main research questions are: * Does L-serine supplementation affect cognitive function, depressive symptoms, and neural functioning in individuals with late-life depression? * What biological mechanisms may underlie the effects of L-serine on cognitive decline? Participants will be randomly assigned to one of two study arms: an intervention group (total n = 42) receiving L-serine at a dose of 6 g/day for 48 weeks, and a placebo group (total n = 42) receiving 6 g/day of maltodextrin for the same duration. All participants will be assessed at three time points: T0 (baseline, prior to trial initiation), T18 (after 18 weeks), and T48 (after 48 weeks, at the end of the trial). At each assessment, participants will: * complete clinical questionnaires and a neuropsychological assessment; * provide blood, fecal, and urine samples; * undergo electroencephalographic (EEG) recordings.

This randomized controlled trial will examine the effects of mindfulness-based interventions and brain stimulation interventions on cognitive function and psychological well-being in older adults. The study will employ a comprehensive assessment approach incorporating psychological evaluations, behavioral assessments, psychophysiological measurements, and neuroimaging analyses to characterize the outcome of nonpharmaceutical interventions in improving geriatric well-being or reducing depression severity.

Depression in the elderly, or "late life depression" (LLD), is often considered to be homogeneous, legitimizing standardized treatment. Yet the literature suggests that there are different forms of LLD, with different pathophysiology, course and treatment. Our experience has led us to identify an "anergic" form, marked by adynamia and anhedonia (anergic depression, AnD). Highly represented among LLDs, it readily resists the usual antidepressants, so that its course is often chronic. Thanks to the "Chronic Anergic Depression Open Trial", the investigators were able to show that AnD responds to dopaminergic (DA) molecules. Therefore the invastigators hypothesized a pathophysiology linked to dysfunction of the mesolimbic DA system. However, not all patients would present the same form: two subgroups could be isolated, each contributing equally. The first corresponds to patients for whom the episode is a recurrence, the so-called "early onset depression" (EOD). The first episode occurs at 34 ±16 years of age and is frequently associated with a personality disorder (73%). The index episode usually lasts 6 ±3 years and is typically associated with anxiety (96%). The second group corresponds to the onset of primary depression after the age of 60, known as "late onset depression" (LOD). The index episode occurs at around 71 ±6 years of age, in people with no premorbid personality disorders. The episode is shorter (3 ±1 years) and anxiety is frequent (75%) but less marked. These patients showed a high propensity for a course compatible with synucleinopathies, but often less rapid than that of the classic forms of these diseases. The investigators hypothesize that within AnD, EOD and LOD present different pathophysiologies, and that this difference is observable on functional magnetic resonance imaging (MRI): LOD patients should present a greater reduction in functional connectivity in the mesolimbic system. The investigators make the subsidiary hypothesis that LODs also show a structural alteration observable with other types of MRI measurements, i.e. multiparametric imaging.

The purpose of this study was to investigate the one-year trajectory of cognitive change in elderly patients with depression, to explore the transfer characteristics and transfer rules of various states of cognitive impairment in patients, to predict the relevant risk factors of cognitive decline, and to find possible influencing factors affecting state change, so as to provide a theoretical basis and reference for subsequent targeted intervention research on geriatric depression.