For free space (line of sight) loss
double the frequency - add 6dB more loss.
A 200 ft. line of sight path, at 2.4GHz has 78dB attenuation.
At 5.8GHz, it's 86dB. - a bit more than 6dB as it's more than double.
The 6 or so dB disadvantage is a relatively small percentage of the attenuation due to distance. Some can be offset with the use of higher gain antennas and more sophisticated MIMO processing (called post-detection gain). Antenna gain (for directional antennas) tends to increase with frequency for the same antenna design and size.
Attenuation from materials (drywall, wood floor, masonry) differs too at the two frequencies. One definitive report was done some years back by the National Institute of Standards (NIST) in the US. It's very informative; NIST and M.I.T. collaborated. They carefully characterized a wide variety of construction materials: drywall, brick. several recipes of poured concrete, block walls, wet/dry plywood and hardwood, etc. Their measurements are in "transmission coefficient" such as free space is 1.0, drywall type x at freq. y is, say, 0.8, and so on. In most cases, the translate the numbers to decibels (dB) for us RF types.
4MB PDF doc. (NIST web site closed like most others due to the current political temper tantrums)
NISTIR 6055
NIST Construction Automation Program
Report No. 3
Electromagnetic Signal Attenuation
in Construction Materials
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=909358
For very large-building indoor cellular distributed antenna systems, and for WiFi, in my field we often use the NIST report's number along with AutoCAD drawing files to quickly build a 3D model of indoor coverage, where autoCAD wall type 1 is mapped to a NIST material attenuation, floor type 2, to another, etc. And we see the AutoCAD files where things like floors as concrete poured over a steel pan exist- makes a big difference.