The cognitive reserve (CR) concept posits that there is individual variability in processing task demands and coping with neurodegenerative diseases. This variability can be attributed to the protective effects derived from continuous cognitive stimulation throughout life, including formal education, engagement in cognitively stimulating activities and occupation. These can result in protection against age-related cognitive decline and reduce the risk of developing Alzheimer’s disease. The aim of this review is to summarize the main features of CR formation and to discuss the challenges in carrying out CR research in developing countries.

To determine the prevalence of dementia associated with Parkinson's disease (PD-D) in a Brazilian sample adopting clinical and diagnostic procedures recommended by the Movement Disorders Society (MDS). Sixty-seven patients were consecutively submitted to neurological, neuropsychological and functional examinations. PD-D was established according to MDS clinical criteria (Level II) and clinical procedures for PD-D (Level I) and prevalence rate was compared between the levels adopted. Ten patients (14.9%) were diagnosed as demented by Level I criteria whereas sixteen (23.8%) were diagnosed based on Level II criteria. Level I criteria had low sensitivity in detecting PD-D (31.25%), but greater specificity (90.19). The PD-D group had significantly worse performance on all neuropsychological tests, were older (p<0.001), had an older age of onset ofdisease (p<0.01), had lower educational level (p<0.02) and had higher scores on functional scales. Current age (p=0.046) and Hoehn & Yahr score (p=0.048) were predictors for developing PD-D. Key words: Parkinson's disease, Parkinson's disease dementia, neuropsychological evaluation.Prevalência da demência associada à doença de Parkinson: uma amostra brasileira RESUMO Determinar a prevalência de demência associada à doença de Parkinson (D-DP) em uma amostra brasileira, adotando os procedimentos diagnósticos e clínicos recomendados pela Movement Disorders Society (MDS). Sessenta e sete pacientes foram submetidos à avaliação neurológica, neuropsicológica e funcional. D-DP foi estabelecida de acordo com os procedimentos (Nível I) e critérios clínicos propostos pela MDS (Nível II) e a prevalência de D-DP foi comparada entre os níveis adotados. A prevalência de D-DP encontrada pelo Nível I e II, foi de 14,9% e 23,8%, respectivamente. O Nível I apresentou baixa sensibilidade em detectar D-DP (31,25%), porém, mostrou alta especificidade (90,19%). O grupo D-DP teve desempenho significativamente inferior em todas tarefas neuropsicológicas, eram mais velhos (p<0,001), mais velhos ao início da doença (p<0,01), menos escolarizados (p<0,02) e elevados escores nas tarefas funcionais. Idade atual (p=0,046) e escore no Hoehn & Yahr (p=0,048) foram apontados como preditores do desenvolvimento de D-DP. Palavras-Chave: doença de Parkinson, demência associada à doença de Parkinson, avaliação neuropsicológica. Correspondence

BackgroundDiffuse axonal injury (DAI), a common cause of neurological sequelae in patients with traumatic brain injury (TBI), is considered one of the most prevalent forms of primary neuronal injury in patients with severe TBI. Cognitive deficits induced by DAI can persist over time, especially following moderate or severe injuries. The aim of the present study was to compare verbal fluency (VF) performance at 6 and 12 months after the trauma in a same group of patients with DAI.MethodsEighteen patients with moderate to severe DAI and 17 healthy volunteers were enrolled. All DAI participants had sustained a TBI at least 6 months prior to the start of the study, were between 18 and 50 years of age, and had at least 4 years of education. The VF test was administered within an extensive neuropsychological test battery. We evaluated the same patients at 6 months (DAI1 group) and 12 months (DAI2 group) and compared the results of neuropsychological tests with a control group of healthy volunteers who were matched to patients for sex, age, and educational level.ResultsIn comparison to controls, the DAI1 group produced significantly fewer words. The DAI2 group produced significantly more semantic words than DAI1 (P<0.05) and demonstrated a trend towards the production of more clusters for letter A (P=0.09) and total words generated in a phonemic test (P=0.09). No significant differences were observed between DAI2 and the control group in the total number of words generated in phonetic FAS or semantic fluency scores.ConclusionThe present findings may be useful in the construction of a management plan for long-term TBI rehabilitation that considers the trauma of each patient. Further, our results suggest the VF test is a suitable instrument for the assessment of cognitive difficulties following TBI.

Herpes simplex virus encephalitis (HSVE) is an inflammation of the brain parenchyma caused by virus, leading to focal necrosis in medial temporal lobes, hippocampal complex and basal forebrain. Cognitively, HSVE is associated to many dysfunctions which vary according to the extent of the lesion. Episodic memory impairment is the most common sequelae following HSVE episodes, although others can occur. The aim of this case report was to describe the cognitive profile of a 42 year-old man who had extensive bilateral damage to the medial temporal lobe, insular bilateral and orbitofrontal cortices due to HSVE. Severe anterograde and retrograde amnesia, naming deficits, perseverative behaviors and confabulations were observed on neuropsychological assessment. We discussed the concept of long term-working memory based on this evaluation. These cognitive impairments corroborated HSVE previous findings in the literature.

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