Brain-Health app and coaching trial aims to prevent dementia in At-Risk seniors

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age between 55 and 75 years at the time of screening. * Fluency in German. * All participants must be able and willing to provide written informed consent form (ICF) prior to any study-related procedures. * Ownership of a compatible Android smartphone, or willingness and capability to use a study-provided Android smartphone for the duration of the study. * Subjective cognitive decline and/or a positive first-degree family history of dementia. * Willingness to make meaningful changes in at least three of six lifestyle domains: dietary counselling, physical activity, cognitive training, vascular risk management, social interaction, and sleep and relaxation. * Cognitive performance at or slightly below age expectations, defined as an m-TICS (modified Telephone Interview for Cognitive Status) score ≥ 37/50, and a Montreal Cognitive Assessment (MoCA) ≥ 26/30. Exclusion Criteria: * Diagnosed or suspected dementia or substantial cognitive impairment, defined as an m-TICS score ≤ 36 or MoCA \< 26, or current or previous use of Alzheimer´s disease or other dementia medication. * Significant neurological disease, including but not limited to Parkinson´s disease, Huntington´s disease, normal pressure hydrocephalus, brain tumour, progressive supranuclear palsy, seizure disorder, subdural haematoma, multiple sclerosis, or a history of significant head trauma with persistent neurological sequelae or known structural brain abnormalities. * Diminished decision-making capacity, inability to provide informed consent, inability to complete study assessments, or any condition preventing effective cooperation, as determined by clinical judgement. * Severe impairment of vision, hearing, or communication abilities that would preclude participation in study procedure. * Any medical or psychiatric condition affecting safe engagement, including but not limited to active malignancy, major depressive disorder, symptomatic cardiovascular disease, or revascularisation procedures within the past year. * Current participation in another interventional trial, unless the study team determines this does not interfere with participation in the LETHE-AT.