Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the most
common form of dementia. Approximately 50% of AD patients show anxiety and depressive
symptoms, which may contribute to cognitive decline. We aimed to investigate whether
the triple-transgenic mouse (3xTg-AD) is a good preclinical model of this co-morbidity.
The characteristic histological hallmarks are known to appear around 6-month; thus,
4- and 8-month-old male mice were compared with age-matched controls. A behavioral
test battery was used to examine anxiety- (open field (OF), elevated plus maze, light-dark
box, novelty suppressed feeding, and social interaction (SI) tests), and depression-like
symptoms (forced swim test, tail suspension test, sucrose preference test, splash
test, and learned helplessness) as well as the cognitive decline (Morris water maze
(MWM) and social discrimination (SD) tests). Acetylcholinesterase histochemistry visualized
cholinergic fibers in the cortex. Dexamethasone-test evaluated the glucocorticoid
non-suppression. In the MWM, the 3xTg-AD mice found the platform later than controls
in the 8-month-old cohort. The SD abilities of the 3xTg-AD mice were missing at both
ages. In OF, both age groups of 3xTg-AD mice moved significantly less than the controls.
During SI, 8-month-old 3xTg-AD animals spent less time with friendly social behavior
than the controls. In the splash test, 3xTg-AD mice groomed themselves significantly
less than controls of both ages. Cortical fiber density was lower in 8-month-old 3xTg-AD
mice compared to the control. Dexamethasone non-suppression was detectable in the
4-month-old group. All in all, some anxiety- and depressive-like symptoms were present
in 3xTg-AD mice. Although this strain was not generally more anxious or depressed,
some aspects of comorbidity might be studied in selected tests, which may help to
develop new possible treatments.
