A case of caffeinism, which presented as a paranoid delusion, is reported as an extreme example of this.
From the independent.co.uk
A study of 60 hospital inpatients revealed that about 40% of them consumed sufficient caffeine to produce symptoms of caffeinism.
From the independent.co.uk
Caffeinism usually combines physical addiction with a wide range of debilitating effects-most notably anxiety, irritability, mood swings, sleep disturbance, depression and fatigue.
From the smh.com.au
More examples
Poisoning resulting from excessive intake of caffeine containing products
Caffeine (also caffein) is a bitter, white crystalline xanthine alkaloid that is a psychoactive stimulant drug. Caffeine was discovered by a German chemist, Friedlieb Ferdinand Runge, in 1820. ...
A toxic condition caused by excessive ingestion of coffee and other caffeine-containing beverages; addiction to such beverages
A disorder caused by ingesting very high doses of caffeine (10g or more per day) and characterized by seizures and respiratory failure.