Mood and male sexual behaviour in the APP23 model of Alzheimer's disease.

Alzheimer's disease is characterised by both cognitive deterioration and the development of a wide range of neuropsychiatric disturbances, among which affective disturbances, stereotyped behaviour, dietary hyperactivity and changes in sexual behaviour. The transgenic APP23 mouse models Alzheimer's disease and has shown to be a unique tool in the study of this condition. APP23 mice develop, next to the age-dependent cognitive decline, also a range of behavioural problems, such as circadian activity disturbances and increased aggression, in analogy with the dementing patients. The present study aimed to investigate whether this model also develops mood disturbances and changes in sexual behaviour. Using two behavioural despair paradigms and the sucrose preference test, we did not find evidence for the development of depression-related behaviours. A sophisticated protocol was neither able to unravel changes in male sexual behaviour between APP23 and WT mice. The present study nevertheless provides evidence that the APP23 mice are more anxious and fearful in comparison with control littermates, which opens perspectives to future treatment studies.