Due to limited time resources in the clinical context, there is a need for instruments which allow a relatively quick and general overview of the cognitive deficits and capacities of a patient entering the rehabilitative process. The assessment of cognitive functions is generally a complex (and may be an intimidating) situation for people having cognitive deficits. This implies that the clinician should respond to the patient’s potential anxieties and reassures the patient during the assessment. Furthermore, the purpose of the respective tests should be explained to the patient in order to promote compliance and reduce frustration. Ideally, the assessment should yield to a written report and an oral feedback to the patient [12].

The so-called screening tests allow gaining a quick and broad overview of diverse cognitive functions in a relatively short amount of time. The majority of cognitive screening instruments consist of a set of different tasks (e.g., memory tasks, word fluency tasks, etc.), whose scores are added up to determine a global score. This totalled score is (ideally) compared to representative norms or cutoff values to quantitatively determine the extent of the patient’s performances or deficits.

One of the most commonly used screening tests for neurocognitive disorders in the medical context is the Mini-Mental State (MMS) or Mini-Mental State Examination (MMSE). The MMSE covers memory, orientation, and attention and assesses the ability to follow written and verbal commands, to name, to write a sentence, and to copy a polygon. In clinical practice, often the raw scores are interpreted, with changing recommendations concerning the cutoff scores. Perneczky and colleagues [13] concluded that the MMSE scores (maximum score is 30) are indicative of the following: 30 no dementia, 26–29 questionable dementia, 21–25 mild dementia, 11–20 moderate dementia, and 0–10 severe dementia. In general, the MMSE is easy and quick to apply and exists in different languages. In the clinical context, the correct interpretation of MMSE scores is however challenging, as the appropriate age- and education-adjusted norms should be taken into consideration. It is known that age and other factors such as psychological comorbidities may influence the results. Furthermore, ceiling effects and poor sensitivities make the detection of mild cognitive impairments in highly educated individuals difficult. Therefore, improvements were made, resulting in the MMSE-2 test [14]. Despite those supplements, it should be noted that other screening tests were developed and are available demonstrating improved sensibilities to detect milder cognitive deficits.

The Montreal Cognitive Assessment (MoCa) is a short screening test with high specificity and sensitivity for detecting mild cognitive deficits. It is more sensitive for discriminating mild cognitive impairment (MCI) from a healthy condition than the MMSE [15]. The MoCA can be administered in 10 min, and it includes a short-term memory recall task and contains two learning trials of five nouns and delayed recall after 5 min. Visuospatial abilities and executive functions are assessed. Furthermore, a phonemic fluency task and a two-item verbal abstraction task are included. Attention, concentration, and working memory are evaluated. Finally, language and orientation to time and place are assessed. The maximum possible score in the MoCA is 30 points. In a recent study, authors found that the MoCA cutoff for differentiating reliably a pathological sample with dementia from a sample composed of healthy controls was 23 (with a specificity of 96% and a sensitivity of 94%; [15]). A score of 19 was found to differentiate reliably between patients with MCI and patients with Alzheimer’s disease, with corresponding specificities ranging from 77% [16] to 80% [15] and sensitivities ranging from 77% [15] to 87% [16].

In addition to the MoCA, the DemTect (originally developed in German) is also a highly sensitive instrument to identify patients with mild cognitive impairments and patients with dementia in early stages of the disease. The DemTect is a brief test (8–10 min completion time) composed of five subtests composed of a word list, a number transcoding task, a word fluency task, a digit span reverse task, and a delayed recall of the previously learned word list. The DemTect is independent from age and education, with total scores ranging from 0 to 18. Performances ranging between 13 and 18 points are considered adequate, between 9 and 12, MCI is probable, and for performances lower than 8, further investigations are necessary as dementia is probable. A parallel version of the test (DemTect-B) has been developed demonstrating equivalent task requirements and difficulties suitable for follow-up evaluations [17].

Another very brief, valid test is the Clock-Drawing Test (CDT). Patients are instructed to draw a clock face with hands; afterward, the clock errors are rated to determine the score. The CDT is a marker of cognitive deficits and is useful as a screen for cognitive impairment. Associations between the CDT and executive functions, global cognitive status, visuospatial processing, and semantic knowledge have been demonstrated [18]. Sensitivities and specificities around 75% in differentiating clinically diagnosed MCI patients from healthy elderly individuals have been shown [19] (Fig. 23.2).

In addition to the assessment of general cognitive functioning with screening tests, a more detailed evaluation of specific functions allows differentiating between altered cognitive functions. Assessment can focus more specifically on attention, learning and memory (e.g., Rey Auditory Verbal Learning Test or Wechsler Memory Scale, Fourth Edition), constructional praxis (e.g., Rey-Osterrieth Complex Figure Test), executive functions (e.g., Stroop test), language (e.g., Boston Naming Test), or psychomotricity (e.g., Trail Making Test).

If attention deficits are suspected, the broad cognitive screening test can be supplemented by an (age-adapted) attention test. In the geriatric context, the nonverbal concentration test for the elderly (AKT [Alters-Konzentrations-Test]) has proven useful and valid [20]. The AKT assesses the ability of an individual to selectively allocate attention to certain stimulus characteristics and to suppress distracting characteristics. The participants’ task is to identify a stimulus figure among a total of 55 two-colored (black and white) figures. Stimulus figures and distracters differ only in their colored pattern and their two-dimensional orientation. A total number of 20 figures can be correctly identified. Dependent variables are the completion time (in seconds) and the percentage of errors. The AKT has excellent psychometric properties with Spearman-Brown split-half reliabilities ranging from r = 0.89 to 0.99 [20]. Dependent variables are the total performance (calculated by adding the correctly identified figures and subtracting the errors), percentage of errors (percentage of distracters erroneously crossed out), and the time to complete the test (in seconds).