tDCS and Cognitive Efficiency in Ageing

This test presents a list of 16 words that, after being read by the evaluator, have to be repeated by the participant. The list is repeated five times (trials); the participant is again asked to remember the 16 words. The test was administered to evaluate the participant's immediate memory (Trial 1), learning ability (Trial 5 ). Post-intervention minus baseline. Scale is scored 0-16. Difference score range is (-16 to 16) with positive scores reflecting improvement.

Direct and inverse digits of the Wechsler Intelligence Scale for Adults-III (Wechsler, 2001). These tests assess attentional capacity by exposing the participant to increasing amounts of information. On the direct digits task, which is used to assess immediate recall, the subject must repeat the sequence of numbers in the same order in which they are read by the examiner. On the inverse digit task, which assesses working memory and mental flexibility, the subject must say the digits backwards from the way they were presented by the examiner. Both tests are evaluated in the same way, assigning one point for each correct item, with a maximum score of 16 for both tests. Post-intervention minus baseline. Difference score range is (-16 to 16) with positive scores reflecting improvement.

This is a screening test for general cognitive status. This test is evaluated on a maximum of 30 points. Participants with scores equal to or below 23 would be considered cognitively deficient. Post-intervention minus baseline. Scale is scored 0-30. Difference score range is (-30 to 30) with positive scores reflecting improvement.

Barcelona Test assesses the ability to access and recall lexical and semantic items by means of two subtests: a. Semantic fluency: recall the highest number of words from the category 'animals' in one minute; b. Phonological fluency: recall the highest number of words beginning with the letter 'p' in three minutes. Minimum and maximum range for Semantic fluency and Phonological fluency: 0 to n (no upper limit). Method of calculation: Scores for each subtest are reported separately. No combined scores or averages between subtests are calculated. Interpretation: Good categorical recall is considered good when evoking more than 16 animals in 1 minute and good verbal fluency when evoking more than 19 words beginning with 'p' in 3 minutes. This test assesses the ability to access and recall items from the lexical and semantic store. Processes involved: processing speed, cognitive flexibility and working memory. Post-intervention less baseline with positive scores reflecting improvement.

This test is evaluated on a maximum of 30 points. Participants with scores equal to or below 23 would be considered cognitively deficient.

This test offers a rapid and effective screening with excellent discriminative properties for amnestic Mild Cognitive Impairment (MCI-A) and early AD in the general primary care population. The test assesses a variety of abilities such as encoding, orientation, semantic memory and free recall. It consists of oral questions with only one possible answer, and the maximum achievable score is 50 points. The optimal cut-off point for distinguishing amnestic-like mild cognitive impairment from subjective memory complaints is 37 points. The optimal cut-off point for Alzheimer's disease is 31 points. Post-intervention minus baseline. Scale is scored 0-50. Difference score range is (-50 to 50) with positive scores reflecting improvement.

This experimental task is composed by three lists of words with two conditions: half and entire.

The half condition included two lists of 50 words each, formed entirely from the following letters of the Spanish alphabet: a, e, u, b, d, g, j, n, r, and z (list A) or i, o, c, f, h, l, m, p, s, t, v, and y (list B).

List C (entire condition) contained 50 words formed from the entire alphabet, with the only criterion being that each word had to contain at least one letter from list A and at least one letter from list B.

In the half condition, the recognition estimates for each participant were derived by subtracting the proportion of false alarms on words with the same letters, as in the study list, from the proportion of hits, whereas in the entire condition, the recognition estimates were derived by subtracting the proportion of false alarms on words with all the letters in the alphabet from the proportion of hits as a way to control the response bias of the participants.