Participants

Sixty old adults (38 women) who did not meet the exclusion criteria, such as the presence of dementia and psychiatric disorders like anxiety or depression, were studied in 2014 and had a follow-up in 2016 (see Table 1). Thirty had hypertension and/or diabetes (CVR group) and 30 did not (NR group). The sample was obtained from a larger study, the CIMVAC, which consists of neurological and neuropsychological assessments of retired workers of the Universidad Autonoma de Nuevo Leon and their close relatives of old age. All of them signed an informed consent form. The CVR group (21 women) had a mean age of 69.9±5.7 years and 13.7±4.7 years of education, while the NR group (17 women) had a mean age of 69.3±5.5 years and 15.5±3.9 years of education. There were no significant differences in sex, age, and education between both groups (p>.05). With the exception of one subject in the NR group who had a previous myocardial infarction, none of the participants had any previous heart condition. There were participants with dyslipidemia in both groups, 8 in the NR group and 13 in the CVR group, but this difference is non-significant (p>.05). In the CVR group, 5 participants (25%) reported not taking any medication to treat their hypertension or diabetes at the time of the first session.

Inclusion Criteria

            The inclusion criteria were the following: age equal to or greater than 60 years old, have or not have diabetes mellitus type 2, have or not have systemic arterial hypertension, have five or more years of education, acceptance to participate and sign the informed consent.

Exclusion Criteria

The exclusion criteria were the following: having less than five years of education, dementia, depression, anxiety, non-competence in activities of daily living, prior history of stroke, moderate or severe traumatic brain Injury, epilepsy, Parkinson’s disease or other diseases of the central nervous system, and not completing the neuropsychological assessment both at baseline and at the follow up session. The presence of psychiatric disorders and daily functioning was assessed through psychological instruments described below, while neurological conditions were determined by standard physical examination and medical history. The cut-off score of 24 in the MMSE was chosen to categorize participants as having dementia or not, since this has been shown to have good sensitivity and specificity to dementia even without any correction for years of education for people in Mexico¹⁶. We excluded participants with less than five years of education because of the effect of this low range of years of education on verbal fluency and MMSE performance, and in order to control for differences in years of education between both groups.

Procedure

The protocol of the study was submitted to the Research Ethics Committee of the Faculty of Medicine of the Universidad Autonoma of Nuevo Leon and was approved with the number NR07-005. Participants completed a neurological and neuropsychological assessment at baseline and at a follow-up session after two years. The neuropsychological assessment was performed by a neuropsychologist or by trained assistants. It consisted of a neuropsychological battery, the Neuropsi Breve, which includes Semantic and Letter Fluency, the Mini-Mental Status Examination, the Geriatric Depression Scale short form, the Adult Manifest Anxiety Scale, and the Instrumental Activities of Daily Living scale. After two years, they were asked for a follow-up session via phone.

Instruments

Semantic verbal fluency and letter verbal fluency consist of naming animals and words with a certain letter for one minute. Letter verbal fluency requires words that start with the letter “F”. We used Troyer⁹ approach to measure Mean Cluster Size and number of Switches, and Abwender¹⁴ approach for measuring Hard Switches and Cluster Switches. We used Troyer⁹ criteria, with some modifications for the Spanish language and the Mexican population, to determine how words are semantically and phonological related to each other to form clusters. For example, the words “vaca”, “toro” and “buey” are semantically related, and the words “gato” and “pato” are phonological related in Spanish language.

Repetitions and Rule Breaks were not counted as CR and were not taken into account for cluster size, however their position did count in determining switch subtype.

Statistical Analysis

Differences in overall verbal fluency performance at baseline were analyzed with two-tailed t tests for independent groups. The effects of time and the interaction of Time and Group in overall performance were analyzed with a mixed Anova, in case ANOVA indicates that there is interaction, a t test was performed for independent samples at two years. Decline between first and second session in other measures of performance was analyzed with one-tailed t tests for correlated groups, but only when there is decline in overall performance of a fluency task.