. Author manuscript; available in PMC: 2014 Jun 1.

Published in final edited form as: Neuropsychol Rev. 2012 Nov 6;23(2):117–137. doi: 10.1007/s11065-012-9222-1

Table 1. Studies Examining Age of Onset of Cannabis Use on Neurocognitive Functioning.

Study	Age	Age of Onset		Healthy Controls	Length of Abstinence	Neurocognitive Domains Poorer in Early-Onset Cannabis Users	Neurocognitive Domains Intact in Early-Onset Cannabis Users
Study	M (SD)	Early (n)	Late (n)	n	minimum	Neurocognitive Domains Poorer in Early-Onset Cannabis Users	Neurocognitive Domains Intact in Early-Onset Cannabis Users
Battisti et al. 2010a	36.10 (11.11)	Mean age = 15.0 (25)		19	12 hours	Earlier onset associated with worse inhibition	--
Ehrenreich et al. 1999	23.25 (unk)	<16 (48)	≥16 (51)	49	2 hours	Visual attention	Divided attention, flexibility in attention, working memory
Fontes et al. 2011a	30.21(unk)	<15 (49)	≥15 (55)	44	Unknown	Executive functioning, inhibition	None
Gruber et al. 2011	22.80 (6.57)	<16 (19)	≥16 (15)	28	12 hours	Verbal fluency, inhibition	Attention, working memory, visuospatial & episodic memory
Gruber et al. 2012	22.75 (2.82)	<16 (9)	≥16 (14)	16	12 hours	None	Inhibition (compared to the late-onset users)
Pope et al. 2003	39.48 (unk)	<17 (69)	≥17 (53)	87	28 days	Verbal fluency, inhibition, episodic & visuospatial memory	Attention, working memory
Solowij et al. 2011	18.30 (0.63)	Mean age = 16.5 (52)		62	12 hours	Earlier onset associated with worse impulsivity	--
Solowij et al. 2012	18.30 (0.63)	Mean age = 16.0 (48)		62	12 hours	Earlier onset associated with worse episodic memory	--

Note: All values are means and standard deviations unless otherwise noted; unk, unknown; --, no other domains evaluated.