openSNP

If you get headaches and/or 'brain fog' without regular caffeine intake, there's a good chance you have caffeine dependence.

https://en.wikipedia.org/wiki/Caffeine_dependence

Phenotype	Number of Users
chronically sore neck glands	45
Allergy to Egg Whites	68
vitiligo	35
Bipolar disorder	55
inverted nipples	43
Diagnosed Vitamin D deficiency	66

User	Variation
Giovanni Mazzola	Non-coffee drinker until mid-30s, steady since, need the first cup in the morning. headaches and fog without coffee now.
Carlan	No
Anaro Lexnon	No
stephen bradley	No
Mary Katharine Bretsch	Yes
pmokeefe	Yes
Samantha B. Clark	No
atelepen	Yes
SamBarzilla	No
correybarone	No
lms18808	Yes
Stinky Jerome	Yes
Ilan	Yes
Brenda Mundt	Yes
Nate S	No
Jessie	Yes
DemonRaven	No
Erin	Yes
jbearden@ieee.org	No
Evo	Yes
jefflagios	Yes
ladynajera	Yes
Curt	No
Mark Jacobs	Yes
Getazaliset	Yes
Klevine	Yes
dlf	Yes
Ebclark	No
Serrak58@gmail.com	No
marty83687	Yes
ceanzi	Yes
otis	No
JGDB	non-coffee drinker until mid-30s, steady since, need the first cup in the morning. headaches and fog without coffee now.
Bastian Greshake Tzovaras	No
GreenStar	No
Chris1507	don´t know
morozmatt	Yes
jellicoe1992	Yes
andygb1947	Don´t know
Annie	Yes
MichaelLloyd	Yes
Kaley White	No
smoothbrainphilosophy	No
Krystalee25	No
ganaiu	Yes
lucasmillen	Yes
Takiwatanga	Yes
mfoley899	No
jordypotty	Yes
P	Yes
blackbookprojects	Yes
Rain.in.the.Forest	Caffeine does nothing for me but I like coffee
Turin Turambar	Yes
bobbybob	No

Non-coffee drinker until mid-30s, steady since, need the first cup in the morning. headaches and fog without coffee now.
No
Yes
Don´t know
Caffeine does nothing for me but i like coffee