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Yeah I do believe it makes a difference, because brain atrophy is linked to a range of cognitive impairments, for example strongly correlated with Alzheimer's d

Yeah I do believe it makes a difference, because brain atrophy is linked to a range of cognitive impairments, for example strongly correlated with Alzheimer's disease. But you're right on the last point though, about assuming thinner is bad automatically. Heavy and chronic cannabis usage has been linked to an increase in density, but a reduction in total volume, which resulted in a slight overall decrease in IQ. The takeaway from all this being: Cognitive function is affected by a variety of parameters and we got more neuroscience to do still.

nonbel 9y ago
>"Heavy and chronic cannabis usage has been linked to an increase in density, but a reduction in total volume, which resulted in a slight overall decrease in IQ." I wouldn't put much stock into these type of non-quantitative explanations wherein "this makes that go up which makes this go down", etc. Usually the researchers measure a bunch of different things, analyze the data in a bunch of different ways, and only publish whatever is "significant". This works at the single lab level and multi-lab level since the "non-significant" results are considered boring and don't get published. By "usually" I mean this is standard behavior. You can call it p-hacking, file drawer effect, and more recently "forking paths": http://andrewgelman.com/2017/12/29/forking-paths-plus-lack-theory-no-reason-believe/ http://andrewgelman.com/2017/12/29/forking-paths-plus-lack-t... >"Cognitive function is affected by a variety of parameters and we got more neuroscience to do still." Sure, that was the case before these studies were done too though.