Investigation of the role of the dopamine transporter in susceptibility to behavioural and psychological symptoms of patients with probable Alzheimer's disease.

BACKGROUND/AIMS: Alzheimer's disease patients commonly suffer from behavioural and psychological symptoms of dementia (BPSD); a genetic component to the development of BPSD has been demonstrated. Genetic risk factors for other psychiatric disorders have been implicated in BPSD; however, this is the first known investigation of the dopamine transporter (DAT1) gene in BPSD.

METHODS

Our large cohort of 395 patients with probable Alzheimer's disease was dichotomised into whether they had ever suffered from a given symptom over the study period or not, based on longitudinal data using the BPSD (Neuropsychiatric Inventory). These measures were related to the DAT1 3'-untranslated region (UTR) variable number tandem repeat (VNTR) polymorphism.

RESULTS

Potential associations were revealed between the 9-repeat allele and presence of irritability and between the 10-repeat allele and aberrant motor behaviour (AMB); however, these do not remain significant after correction for multiple testing. No associations were observed with delusions, hallucinations, depression, agitation/aggression or elation.

CONCLUSION

Our data suggest that the DAT1 3'-UTR VNTR could play a role in susceptibility to irritability and AMB. The findings presented here require replication in large well-characterised cohorts.