Australian researchers have debunked the long-held “baby brain” theory, suggesting new parents are no less astute than non-parents.

Monash University researchers conducted a comprehensive memory and cognition study with 150 new mums and 150 new dads for up to two years after the birth of their baby.

Armed with a raft of cognitive assessments, they found new parents performed similarly to a non-parent control group on all cognition measures.

The outcome suggests an absence of the so-called effect of “baby brain”, said study co-author Kelsey Perrykkad from Monash’s Turner Institute for Brain and Mental Health.

Lead author of the study Navyaan Siddiqui said researchers had expected mothers and fathers to show reduced cognition both subjectively and objectively compared to non-parents, due to significant sleep disruptions and other physiological and psychosocial changes.

“We expected that there would be little to no difference between the new mums and dads on account of their shared environment post birth and we also expected that cognition would improve in parents with increased time postpartum,” he said.

But what they found was that time had no effect on any cognitive measures, with parents’ ability remaining the same regardless of the baby’s age up to two years.

There was “robust evidence”, however, for poorer sleep equating to worse subjective memory across the sample.

It means the cognition of new parents is not impaired — even if feels like it.

The study, published in the journal Cortex, concluded there was “no evidence for objective reductions in cognition in postpartum mothers or fathers relative to non-parents”.

“When we do find evidence for baby brain, it is more related to sleep and wellbeing than a true objective decline in cognition,” Dr Perrykkad said.

“This indicates it is just as important as ever to support new parents in these formative years.

“While it isn’t the end of the baby brain story, new parents can take solace in the fact that becoming a new parent doesn’t inherently impair their memory and cognition.”