I'm doing a PhD in behavioural psychology but it's not my ideal topic of interest. I'm interested in neuroscience and I would like to pursue a PhD in this field.

I'm 6 months into my PhD, it's fully funded and to be honest, it's not that bad.
With the economy like it is at the moment, should I complete the PhD and move into neuroscience later?

Opinions are welcome, thanks in advance.

I would say if you find something in your interest area, and you have secured a place, then move over. However, do not move over unless you have secured a place. 6 months is a very short time, so it is not like you have wasted time.