Armando Estévez-González

Chronic effects of dopaminergic replacement on cognitive function in Parkinson's disease : A two-year follow-up study of previously untreated patients

The cognitive effects of dopaminergic treatment in Parkinsons disease (PD) are still controversial.

Semantic Knowledge of Famous People in Mild Cognitive Impairment and Progression to Alzheimer’s Disease

Patients with dementia of Alzheimer’s type (DAT) show severe impairment in recognizing famous people. The aim of the current study was to investigate if this well-known memory impairment of famous faces is already present in the preclinical phase of DAT and if the famous faces test can help to differentiate patients with mild cognitive impairment (MCI) who progress to dementia and those who do not. We compared baseline performance in a task of famous face identification in a sample of 116 patients with subjective memory complaints classified in three groups: 17 participants with no evidence of cognitive impairment; 26 patients with MCI who had not developed dementia, and 27 patients with MCI who had developed probable DAT 2 years later. The remaining patients were excluded because they abandoned or did not meet the applied restrictive criteria for DAT, MCI or control. MCI patients who were diagnosed 2 years later with DAT performed significantly worse in the preclinical phase than MCI and control participants (p < 0.004). Patients with MCI but not DAT obtained intermediate results between control subjects and MCI patients who develop Alzheimer’s disease. A neuropsychological task of semantic knowledge of famous people may be useful in the early diagnosis of Alzheimer’s disease.

Right Hemisphere Dysfunction in Subjects With Attention-Deficit Disorder With and Without Hyperactivity

The attention-deficit disorder, with and without hyperactivity, is associated with defective attention, response inhibition and, in attention-deficit disorder with hyperactivity, with motor restlessness. In adults, inattention, defective response inhibition, and impersistence are more commonly seen in right hemisphere lesions. In the present study, we investigate possible right hemisphere dysfunctions in attention-deficit disorder with hyperactivity and attention-deficit disorder without hyperactivity. The right hemisphere performance of 60 teenagers, 16 having attention-deficit disorder with hyperactivity, 9 having attention-deficit disorder without hyperactivity, and 35 controls, selected clinically (DSM-III) and experimentally (through Continuous Performance Test and Paced Auditory Addition Task), with normal IQ was assessed using a wide-ranging battery of visuospatial, visuoperceptive, and visuoconstructive functions (Bentons Line Orientation, Bentons Visual Retention, Ravens Progressive Matrices, Wechsler Adult Intelligence Scale [WAIS] Block-Design, Reys Complex Figure). Teenagers with attention-deficit disorder with and without hyperactivity performed significantly worse than controls. Greater differences were found between subjects with attention-deficit disorder without hyperactivity and control than between subjects with attention-deficit disorder with hyperactivity and control subjects. Our results seem to be consistent with right-hemisphere dysfunction, especially in subjects with attention-deficit disorder without hyperactivity. Additionally, WAIS Block-Design and Bentons Line Orientation are the visuospatial tests with the highest discriminant power to differentiate between controls, subjects with attention-deficit disorder without hyperactivity, and subjects with attention-deficit disorder with hyperactivity. (J Child Neurol 1997;12:107-115).

Effects of repetitive transcranial magnetic stimulation on memory subtypes: a controlled study.

Repetitive transcranial magnetic stimulation (rTMS) of human cortex may disrupt or facilitate cortical activity. The aim of the present study was to investigate the consequences of rTMS applied over different cortical areas during various memory tasks, measuring immediate, working and episodic verbal memory. The study was performed in 16 right-handed healthy men. A double-blind, cross-over, within-subject repeated measures design was used. There were five rTMS conditions: baseline without stimulation, high frequency (HF) rTMS over right and left dorsolateral prefrontal cortex (DLPFC) and over right cerebellum, and low frequency (LF) parameters over left DLPFC. Digits forwards and backwards and letter-number sequencing of the Wechsler Adults Intelligence Scale (WAIS) were used to assess immediate and working verbal memory, and logical memory of the Rivermead Behavioural Memory Test was used to assess episodic memory encoding. An analysis of variance (ANOVA) for repeated measures in the scores of each memory task according to rTMS conditions was used. Significantly lower scores in the number of memory units of the episodic memory task were observed when rTMS high frequency parameters were applied over left DLPFC (P=0.009). No significant differences were found in the other memory subtype tasks analysed during the different rTMS conditions. These findings provide evidence for the significant role of the left DLPFC in episodic verbal memory processes.

Preclinical memory profile in Alzheimer patients with and without allele APOE-epsilon4.

To investigate the association between APOE-Ε4 allele and memory phenotype in the preclinical stage of Alzheimer’s disease (AD). We compared an extensive preclinical memory profile at the baseline evaluation of 2 AD genotype groups: APOE-Ε4 allele carriers and patients with APOE-Ε3 homozygosity. Baseline memory performance was carried out at least 2 years (interval of 27.7 ± 4 months) before AD diagnosis was established, and analysis included different modalities of working memory (visuoperceptive, visuospatial, digit span and processing speed), of declarative memory (recent, verbal learning, prospective and semantic) and of nondeclarative memory (procedural, incidental and priming). We found no significant differences: memory performance was similar in both genotype groups. The presence of the APOE-Ε4 allele does not seem to be sufficient to cause a distinctive preclinical memory phenotype in AD patients.