The first aim of the observational study is the translation, cross-cultural adaptation and validation of functional and behavioral scales used in the diagnosis of neurodegenerative diseases, for which a formal version in Italian is not available at present. In particular, the study includes the following functional and behavioral scales: the Katz's index (Basic Activities of Daily Living, BADL), the Lawton and Brody's scale (Instrumental Activities of Daily Living, IADL), the Everyday Cognition questionnaire (E-Cog), the Neuropsychiatric Inventory Questionnaire (NPI-Q) for assessing the Behavioral and Psychological Symptoms of Dementia. Furthermore, a modified Italian version of the Functional Activities Questionnaire (FAQ), which integrates and updates the content of the original items (e.g., addressing the use of technologies, M-FAQ) will be used in the validation study.

The second aim is to evaluate the psychometric properties of the M-FAQ, the ECog, and the NPI-Q in terms of reliability and validity.

The third aim is to apply a Receiver Operating Characteristic (ROC) curve analysis to identify cut-offs of IADL, M-FAQ and ECOG to discriminate between different clinical groups (i.e., neurologically unimpaired elderly; Subjective Cognitive Decline, SCD; Mild Cognitive Impairment, MCI; mild Alzheimer's Disease, AD).

Neurologically unimpaired elderly participants (over 60 years old) and participants with SCD, MCI, mild AD, and their caregivers/informants will undergo: i) administration of the translated versions of the scales; ii) administration of a Cognitive Reserve questionnaire. For SCD, MCI and AD participants, data from the clinical neuropsychological evaluation will also be collected, while paper-and-pencil psychometric tests to assess global cognitive functioning (Mini Mental State Examination) and logical-abstract reasoning (Raven's Colored Matrices) will be administered to the neurologically unimpaired participants.

Background Increasing aging in high-income countries, linked to increased life expectancy and declining birth rates, is accompanied by an exponential increase of dementia.

While the use of psychometric cognitive tests validated in different clinical populations is commonly used in clinical practice, there is a relative lack of validated Italian-language tools to assess functional autonomy abilities and detect the presence of neuropsychiatric symptoms, even though these are essential aspects for diagnostic, prognostic, and preventive purposes.

The assessment of functional indepedence is particularly important in the diagnosis of Mild Cognitive Impairment (MCI), where the presence of substantially intact or minimally impaired functional abilities is not easy to operationalize and measure, although it has significant relevance especially in the differential diagnosis with overt mild dementia. Currently, the functional scales most used in clinical settings are the Basic Activities of Daily Living scale (BADL), the Instrumental Activities of Daily Living scale (IADL) and the Functional Activities Questionnaire (FAQ). However, the Italian versions of these tools are informal. The group of Farias and colleagues (2008) has more recently developed a new assessment tool, the Everyday Cognition questionnaire (ECog), with a focus on functional changes in specific cognitive domains (memory, language, visuospatial skills, and executive functions).

The Neuropsychiatric Inventory (NPI) is one of the most widely used tools for assessing the Behavioral and Psychological Symptoms of Dementia (BPSD) in research, covering a wide range of neuropsychiatric symptoms. In 2000, a questionnaire form was published, the Neuropsychiatric Inventory Questionnaire (NPI-Q), which is more suitable for use in routine clinical practice and has been validated in several countries, but not in Italian.

Study design According to a power analysis, 300 neurologically unimpaired elderly participants and 90 participants, divided into Subjective Cognitive Decline (SCD), Mild Cognitive Impairment (MCI) and mild Alzheimer's Disease (AD), will participate in the study.

Inclusion criteria:

For all groups: i) Age ≥ 60 years; ii) Availability of an informant/caregiver, able to judge their functional abilities.

For neurologically unimpaired elderly: i) Normal performance on the Mini Mental State Examination.

For clinical groups: conditions consistent with:

• Subjective Cognitive Decline;
• Mild Cognitive Impairment;
• Mild Major Neurocognitive Disorder. Exclusion criteria
• Other neurological or psychiatric conditions that may explain the presence of cognitive difficulties and refusal or inability to sign informed consent.

Methods Participants and their caregivers/informants will undergo: i) Detailed information of the purpose and modalities of the study, verification of eligibility criteria, signing of informed consent; ii) Collection of demographic and anamnestic data; iii) Administration of the translated versions of the functional rating scales and NPI-q; iiii) Administration of a Cognitive Reserve questionnaire (e.g., Cognitive Reserve Index questionnaire).

For SCD, MCI and AD participants, data from the neuropsychological evaluation clinically performed will also be collected.

Two paper-and-pencil psychometric tests will be administered to neurologically unimpaired participants, to assess global cognitive functioning (Mini Mental State Examination) and logical-abstract reasoning (Raven's Colored Matrices).

Each functional scale will be administered both in the self-report version, in which the participant will provide responses relative to his or her own functioning, and in the informant version, in which the informant or caregiver will be asked to give a rating to his or her relative or friend's functioning in daily activities. The NPI-Q will be administered only to the informant.

Socio-demographic information (age, gender, manual laterality, education, and cognitive reserve assessed through specific questionnaires, e.g., CRI-Q) will be collected from all participants.

A pilot version of each translated scale will be administered, as a semi-structured interview, to about 20 participants and their informants, in order to obtain a final version for each tool to be used in the validation study.

Statistical analysis The distribution of the responses provided by the four clinical groups to the different items of the functional scales (ADL, IADL, M-FAQ and ECog) and the NPI-Q questionnaire will be analyzed to detect the presence of any ceiling and floor effects. The degree of agreement between the self-administered version and the informant version in each tool will be assessed. Cronbach's Alpha coefficient will be employed to analyze the internal consistency of ECOG, M-FAQ and NPI-Q. Convergent validity between functional scales will be calculated.

A confirmatory factor analysis will be employed to examine the factorial structure of the ECog compared to the original version.

Discriminant validity will be assessed by comparing M-FAQ and ECOG by the four scores in different clinical groups through logistic regression models.

Finally, a Receiver Operating Characteristic (ROC) curve analysis will finally be applied to identify cut-offs of IADL, M-FAQ, and ECOG to discriminate among the different clinical groups.

Expected results Italian versions of functional and behavioral scales will be obtained, according to a rigorous cross-cultural adaptation procedure, and overcoming divergences between the available Italian informal versions.

The study will also make available a modified version of the Functional Activities Questionnaire (M-FAQ) that integrates and updates the original items.

Pre-clinical and clinical validation of the tools included in the study will improve early diagnosis and longitudinal monitoring overtime.

Inclusion Criteria:

• Age ≥ 60 years;
• Availability of an informant/caregiver, able to judge their functional abilities.

For neurologically unimpaired elderly:

- Normal performance on the Mini Mental State Examination (Folstein et al. 1975; Foderaro et al., 2022).

For clinical groups: Conditions consistent with:

• Subjective Cognitive Decline (Jessen et al., 2014)
• Mild Cognitive Impairment (Winblad et al., 2004)
• Mild Major Neurocognitive Disorder according (DSM-5-TR, APA, 2022).

Exclusion Criteria:

• Refusal or inability to sign informed consent;
• For the clinical groups: other neurological or psychiatric conditions that may explain the presence of cognitive difficulties.

The study will enroll neurologically unimpaired participants and participants with SCD, MCI, and mild dementia referred to the Center for Cognitive Disorders and Dementia.