Objective: To determine, using a systematic review of case-control studies, whether head injury is a significant risk factor for Alzheimer's disease. We sought to replicate the findings of the meta-analysis of Mortimer et al (1991). Methods: A predefined inclusion criterion specified case-control studies eligible for inclusion. A comprehensive and systematic search of various electronic databases, up to August 2001, was undertaken. Two independent reviewers screened studies for eligibility. Fifteen case-control studies were identified that met the inclusion criteria, of which seven postdated the study of Mortimer et al. The most convincing evidence to date in support of an association between head injury and Alzheimer's disease is the meta-analysis by Mortimer et al of seven case-control studies conducted before 1991. 5 In this study, the raw data for each case-control study were collected directly from the original authors. Mortimer et al reported a relative risk of 1.82 (95% confidence interval (CI) 1.26 to 2.67) for head injury with a loss of consciousness. 5 The relative risk, when adjusted for a family history of dementing illness, education, and alcohol consumption, remained significant but was only true for males (2.67, 95% CI 1.64 to 4.41) and not females (0.85, 95% CI 0.43 to 1.70).In view of the equivocal findings from Mortimer et al's study, 5 and knowing that further case-control studies have been reported, we aimed to replicate the findings of Mortimer et al using a systematic review of case-control studies conducted in the past 10 years. We also sought to review the evidence for a relation between APOE status and head injury as risk factors for Alzheimer's disease. We have primarily relied on the data presented in published papers and, consequently, were unable to analyse covariate risk factors such as alcohol consumption, family history of dementing illness, and education. METHODS Inclusion criteriaThis study identified case-control studies that reported on head injury, or the interaction between head injury and APOE status, as risk factors for Alzheimer's disease. The inclusion criteria were developed on the basis of a comprehensive review of the literature, and consideration of the criteria used by Mortimer et al, 5 in order to identify the major sources of potential bias and the measures taken in an attempt to minimise such bias. Seven factors were identified as essential requirements for entry into this study:(1) Head injury with loss of consciousness: We were interested in head injury of a severity that occurs infrequently and that is likely to produce neurological effect. Therefore, we required that studies defined head trauma in terms of the presence of loss of consciousness. By excluding lesser head injuries, studies should be less exposed to recall bias and less likely to find an association that merely reflects a consequence of the prodrome of the dementia. No time restriction was placed on the period of unconsciousness.(2) Matching of case and control subjects: Two different types o...

The results support the notion of post-concussion symptoms as a collection of associated but at least partially separable cognitive, emotional and somatic symptoms, although questions persist regarding symptom specificity. The use of the RPQ is discussed, and classification bands for use in clinical practice are suggested.

More attention needs to be paid to neuropsychiatric functioning

No abstract

Hippocampal activation was investigated, comparing allocentric and egocentric spatial memory. Healthy participants were immersed in a virtual reality circular arena, with pattern-rendered walls. In a viewpoint-independent task, they moved toward a pole, which was then removed. They were relocated to another position and had to move to the prior location of the pole. For viewpoint-dependent memory, the participants were not moved to a new starting point, but the patterns were rotated to prevent them from indicating the final position. Hippocampal and parahippocampal activation were found in the viewpoint-independent memory encoding phase. Viewpoint-dependent memory did not result in such activation. These results suggest differential activation of the hippocampal formation during allocentric encoding, in partial support of the spatial mapping hypothesis as applied to humans.