A Multiple Indicators Multiple Causes (MIMIC) model of Behavioural and Psychological Symptoms in Dementia (BPSD)

INTRODUCTION

Although there is evidence for distinct behavioural sub-phenotypes in Alzheimer's disease (AD), their inter-relationships and the effect of clinical variables on their expression have been little investigated.

METHODS

We have analysed a sample of 1850 probable AD patients from the UK and Greece with 10 item Neuropsychiatric Inventory (NPI) data. We applied a Multiple Indicators Multiple Causes (MIMIC) approach to investigate the effect of MMSE, disease duration, gender, age and age of onset on the structure of a four-factor model consisting of "psychosis", "moods", "agitation" and "behavioural dyscontrol".

RESULTS

Specific clinical variables predicted the expression of individual factors. When the inter-relationship of factors is modelled, some previously significant associations are lost. For example, lower MMSE scores predict psychosis, agitation and behavioural dyscontrol factors, but psychosis and mood predict the agitation factor. Taking these associations into account MMSE scores did not predict agitation.

CONCLUSIONS

The complexity of the inter-relations between symptoms, factors and clinical variables is efficiently captured by this MIMIC model.

Nanotechnology--salvation or damnation for humans?

Nanotechnology is a term derived from the Greek word nanos, meaning dwarf. It is used to describe activities at the level of atoms and molecules. The application of this technology is aimed at controlling and manipulating the physical properties of materials with single molecule precision. Scientists use the technology to build working devices, systems and materials, molecule by molecule. This enables them to exploit the unique and powerful electrical, physical and chemical properties found at that scale. Nanotech holds the potential to revolutionise medicine, electronics and chemistry. Nanomedicine would facilitate the repair and improvement of the human body from the inside out, with a precision and delicacy far greater than the finest surgical instruments permit. Problem areas stemming from the technology include the following:- Who will benefit - just the rich or the poor as well? This paper will explore the role of law, ethics and suitable control mechanisms to limit the dangers and maximise the benefits of nanotechnology for society, especially in the field of medicine.

Calcification of the basal ganglia as a cause of levodopa-resistant parkinsonism

We present a patient with levodopa-resistant parkinsonism due to basal ganglia calcification related to surgically-induced hypoparathyroidism. The calcification was seen on computerized axial tomography but not on skull x-rays. Such calcification should be looked for in all cases of levodopa-resistant parkinsonism, since it is possible that treatment of hypoparathyroidism may halt progression of the disease. This case with similar ones from the literature suggest that striatal disease itself can cause parkingonism and that the parkinsonism in such patients tends to be less responsive or nonresponsive to levodopa.