An informant questionnaire for detecting Alzheimer's disease: are some items better than others?

A decline in everyday cognitive functioning is important for diagnosing dementia. Informant questionnaires, such as the informant questionnaire on cognitive decline in the elderly (IQCODE), are used to measure this. Previously, conflicting results on the IQCODEs ability to discriminate between Alzheimer's disease (AD), mild cognitive impairment (MCI), and cognitively healthy elderly were found. We aim to investigate whether specific groups of items are more useful than others in discriminating between these patient groups. Informants of 180 AD, 59 MCI, and 89 patients with subjective memory complaints (SMC) completed the IQCODE. To investigate the grouping of questionnaire items, we used a two-dimensional graded response model (GRM).The association between IQCODE, age, gender, education, and diagnosis was modeled using structural equation modeling. The GRM with two groups of items fitted better than the unidimensional model. However, the high correlation between the dimensions (r=.90) suggested unidimensionality. The structural model showed that the IQCODE was able to differentiate between all patient groups. The IQCODE can be considered as unidimensional and as a useful addition to diagnostic screening in a memory clinic setting, as it was able to distinguish between AD, MCI, and SMC and was not influenced by gender or education.

How useful is the IQCODE for discriminating between Alzheimer's disease, mild cognitive impairment and subjective memory complaints?

BACKGROUND: Informant questionnaires may be useful in diagnosing early dementia. Conflicting results were found when these questionnaires were used to differentiate patients with mild cognitive impairment (MCI) from healthy elderly subjects. We evaluated the ability of the most commonly used informant questionnaire, the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), to discriminate between Alzheimer's disease (AD), MCI and subjective memory complaints (SMC). METHODS: Informants of 180 AD patients, 59 MCI patients and 89 SMC subjects who visited the Alzheimer Center of the VU University Medical Center between 2004 and 2007 completed the short Dutch version of the IQCODE. Logistic regression and receiver operating characteristic curves were used to evaluate the diagnostic ability of the IQCODE. RESULTS: The IQCODE was able to differentiate AD from MCI and SMC, but was not able to differentiate SMC from MCI. CONCLUSIONS: The IQCODE may be helpful in diagnosing AD but is of limited use in differentiating MCI from SMC.

Reverse breeding: a novel breeding approach based on engineered meiosis.

Reverse breeding (RB) is a novel plant breeding technique designed to directly produce parental lines for any heterozygous plant, one of the most sought after goals in plant breeding. RB generates perfectly complementing homozygous parental lines through engineered meiosis. The method is based on reducing genetic recombination in the selected heterozygote by eliminating meiotic crossing over. Male or female spores obtained from such plants contain combinations of non-recombinant parental chromosomes which can be cultured in vitro to generate homozygous doubled haploid plants (DHs). From these DHs, complementary parents can be selected and used to reconstitute the heterozygote in perpetuity. Since the fixation of unknown heterozygous genotypes is impossible in traditional plant breeding, RB could fundamentally change future plant breeding. In this review, we discuss various other applications of RB, including breeding per chromosome.