Different brain areas work better at different ages

Washington: MIT scientists have found that different parts of the brain work best at different ages.

Neuroscientists at Massachusetts Institute of Technology (MIT) and Massachusetts General Hospital (MGH) gathered data from nearly 50,000 subjects and found that each cognitive skill they tested peaked at a different age.

For example, raw speed in processing information appears to peak around age 18 or 19, then immediately starts to decline.

Short-term memory continues to improve until around age 25, when it levels off and then begins to drop around age 35.

For the ability to evaluate other people's emotional states, the peak occurred much later, in the 40s or 50s.

"At any given age, you're getting better at some things, you're getting worse at some other things, and you're at a plateau at some other things," said Joshua Hartshorne, a postdoc in MIT's Department of Brain and Cognitive Sciences.

"There's probably not one age at which you're peak on most things, much less all of them," he said.

"It paints a different picture of the way we change over the lifespan than psychology and neuroscience have traditionally painted," added Laura Germine, a postdoc in psychiatric and neurodevelopmental genetics at MGH.

The researchers, graduate students at Harvard University in 2011, dug out sets of data, collected decades ago, on adult performance at different ages on the Weschler Adult Intelligence Scale, which is used to measure IQ, and the Weschler Memory Scale.

Hartshorne and Germine developed a new way to analyse the data that allowed them to compare the age peaks for each task.

"We were mapping when these cognitive abilities were peaking, and we saw there was no single peak for all abilities. The peaks were all over the place. This was the smoking gun," Hartshorne said.

The researchers also tested several of the same cognitive skills with larger pools of Internet study participants.

For the Internet study, the researchers chose four tasks that peaked at different ages, based on the data from the Weschler tests. They also included a test of the ability to perceive others' emotional state, which is not measured by the Weschler tests.

The study also included a vocabulary test, which serves as a measure of what is known as crystallised intelligence, the accumulation of facts and knowledge.

These results confirmed that crystallised intelligence peaks later in life but the researchers also found something unexpected: While data from the Weschler IQ tests suggested that vocabulary peaks in the late 40s, the new data showed a later peak, in the late 60s or early 70s.

The researchers believe this may be a result of better education, more people having jobs that require a lot of reading, and more opportunities for intellectual stimulation for older people.

The study appears in the journal Psychological Science.