For healthy aging, reports are less consistent. Although it is well documented that it is accompanied by significant changes in slow wave activity, there is still much controversy over the specific patterns of these alterations, their underlying causes and their behavioral significance (e.g.151819). Some studies report that age-related power increases in slow frequencies are indicative of subsequent cognitive deterioration. Prichep et al.34 showed that baseline excess of absolute and relative theta power could predict future cognitive decline in subjects who initially reported subjective cognitive complaints but showed no objective evidence of cognitive impairment. Stomrud et al23 reported that increased theta power in healthy older adults correlated with reductions in mean peak frequency, changes in cerebrospinal fluid and decreased cognitive speed. These alterations resembled AD pathology, therefore the authors interpreted their findings as reflecting possible early mild brain pathology, already present in healthy elderly individuals.
