"Sometimes ADD can look like manic-depressive illness due to the high energy level involved in both syndromes. Manic-depressive illness is characterized by periodic momentous mood swings, from very high to very low. The very high moods, called periods of mania, can resemble ADD in that they include highly active behavior, easy distractibility, impulsivity, and an apparent disregard for personal safety.

ONe can distinguish between mania from the high energy of mania by the level of intensity. An average person could simulate the energized state of ADD, but could not voluntarily reproduce the energy level of mania. Mania is the most extreme form of non-drug-induced drivenness that we know.The manic person can go without sleep for days, traveling the globe or spending his life's savings on wild schemes or making gradniose claims of self-importance or talking nonstop from morning until night.

While the individual with ADD can branch from topic to topic, he does not do so with the suddenness or pressuredness that the manic does.

The two sydromes can actually coexist. The person with ADD may become manic for a period of time, and may cycle into depression as well." (Hallowell and Ratey 2011)

"ADHD and mania share many symptoms and several pathogenetic aspects. The common belief that stimulants are contraindicated in mania has been challenged, and controlled trials to study the possible antimanic effects of vigilance-stabilizing drugs such as stimulants are justified and necessary." (Hegerl at al. 2010)

"The third explanation of a shared diathesis (be it reflecting a biological or environmental factor) has been widely considered. In relation to a genetic contribution, Faraone et al. 10 undertook a meta-analysis of relevant family-based studies and quantified that relatives of probands with a bipolar disorder had a higher chance of having ADHD and, in addition, that bipolar I disorder was more prevalent in relatives of ADHD probands. Comparelli et al. 8 also overviewed studies quantifying that relatives of patients with either condition had a greater chance of having the other condition and with genetic studies quantifying up to 33 shared loci and so supporting a genetic contribution. However, a Consortium 11 genome-wide analysis quantified only a small (albeit significant) genetic correlation and instead supported gene by environment interactions as a stronger candidate explanation." (Parker 2025)