Research has shown that Alzheimer (AD) patients manifest deterioration in language production. The current (diagnostic) instruments for language assessment (in general, as well as in relation to dementia) largely focus on product measures, such as phrase length and number of errors. However, the processes leading to spoken and written text production provide insight into language ability as well. This research project aims to develop valid sentence production tasks that enable researchers and clinicians to adequately characterize the longitudinal decline of on-line written language production in AD. These aims will be addressed in three consecutive studies:
1. an exploratory study,
2. a cross-sectional study, and
3. a longitudinal study.
Since findings from previous research indicate the need for a screening task that assesses multiple components of language, we will combine writing tasks that focus on motor (physical typing skills), cognitive (mind) and linguistic (language) aspects. Therefore, during an exploratory study we aim to develop a number of highly controlled sentence production tasks that assess a set of predefined cognitive and linguistic process aspects.
In the exploratory study, we aim to initially develop 60 picture combination cards; groups of separate pictures that elicit a written sentence. During the experiment, participants are instructed to include the objects depicted when producing a sentence and to link them with a verb that fits the situation. The observation method used is keystroke logging via the in-house developed tool Inputlog, which is non-intrusive, time-saving, and hence cost-reducing, when compared to other tools or techniques. By using validated pictures we can easily predetermine the words participants will probably use when producing a sentence and hence monitor specific word characteristics that influence cognitive pauses. Recent explorations on related linguistic data proved the discriminatory power of determiners, nouns, verbs (and adjectives) for distinguishing between participant groups. Therefore, these word categories will be the main focus of the elicited sentences.
Cross-sectional and longitudinal study
Based on the findings of the exploratory study, the number of picture combination cards needed (via statistical techniques like Generalizability and Design study) will be reduced to an optimal minimum. In the experimental cross-sectional study patients with mild cognitive impairment (MCI), mild AD and a healthy control group will be involved. The participants will be asked to perform a brief copy task (motor and typing skills) and to produce sentences (cognitive and linguistic skills) based on randomly selected picture combination cards. Finally, in the longitudinal study, the cross-sectional study will be replicated after six and twelve months in order to document the (potential) cognitive decline. We will opt for mixed effects models in which the random effects of subjects, sentences and words are modeled.
A secondary goal of this research project is to further automatize data analysis and report generation allowing clinicians to interpret the data instantly. Since we trigger predefined nouns, verbs and adjectives in our study, we should be able to further automatize the analysis and reporting via Inputlog.