The participants were 268 (161 females). Their age ranged from 65 to 98 years (mean [M] = 73.50, standard deviation [SD] = 7.07). Two groups were formed, the first with a diagnosis of AD (n = 122; 72 women), and the second healthy controls (HC; n = 146; 89 women). Participants were matched regarding their basic demographics, such as age [t(266) = 1.147, p = 0.253], gender χ2(1) = 0.105, p = 0.746, and years of education [t(266) = 0.271, p = 0.786]. All participants reported the same socioeconomic status (lower middle-class, based on their annual income and education).

Participants’ diagnosis of AD was made at the Memory and Dementia Outpatient Clinic in G. Papanikolaou General Hospital, Thessaloniki and controls were recruited from the community. Although recruitment took place between June 2013–September 2015 at Thessaloniki, participants came from different parts of Northern Greece. The patients were included consecutively, while the HCs were selected based on their demographics, and in order to match the group of patients. The dropout rate was low (9.15%), given that of the 295 participants, only 27 participants (and/or their caregivers in the case of the AD patients group) refused to be included in the study protocol, mainly due to time restrictions (insufficient time) for the completion of the full examination. This study has been approved by the Ethics Committee of Aristotle University of Thessaloniki (protocol 2.27/3/2013) and was conducted according to the guidelines of the Declaration of Helsinki. Written informed consent was obtained from all patients and their caregivers.

Inclusion criteria were (1) aged ≥ 65 years (in older to define this a homogeneous group of elderly participants), (2) a first (not pre-existing) diagnosis of AD according to the established guidelines from the National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer’s Disease and Related Disorders Association Inc. (NINCDS-ADRDA) and the diagnostic criteria of neurocognitive disorders provided by DSM‑5 (as re-examined after the data collection) at the time of the examination, and (3) Greek native speakers. Exclusion criteria were (1) a history of other neurological or psychiatric illness (e.g., severe mental illness, stroke, epilepsy, sensory impairments not corrected with aids), both ongoing and past, and (2) inexistence of a reliable third source to confirm the existence of stressful events.

General cognition was measured with Mini-Mental State Examination (MMSE), depressive symptomatology was assessed with the 15-item Geriatric Depression Scale and the culturally appropriate cut-off of 6/7 point was applied [9]. None of the participants had a score above this cut-off (MGDS-15 = 2.39, SDGDS-15 = 3.24). Financial capacity was assessed with the Legal Capacity for Property Law Transactions Assessment Scale (LCPLTAS) [7]. To evaluate stress level, the Social Readjustment Rating Scale (SRRS) or better known as Holmes and Rahe Stress Scale was used. With this scale, each reported event is called a life change unit (LCU) and has a different ‘weight’ for stress. More events mean a higher score and the higher the self-reported score, and the larger the weight of each event, the more likely the patient would become ill. The total score is based on adding the total life change units occurring during the last year, with the following ranges: 0–149 LCU = low stress, 150–299 LCU = moderate stress, and 300 plus LCU = high stress [10]. In this sample, stressful life events ranged from 0–254. In addition to the older person, at least one more person (family member or caregiver) that accompanied them during the neuropsychological assessment, confirmed the existence of the stressful events.