Table 1.

Cognitive Effects in Acute vs. Chronic Smokers with SZ.

Study	Study design	Control for time since last cigarette	Findings
(16)	Cross-sectional	No control for last cigarette	= cognition No significant differences in cognitive outcomes between smokers and non-smokers with first-episode SZ
(17)	Cross-sectional	Last cigarette an hour prior to testing	↓ cognition Treatment-resistant SZ smokers performed worse on problem-solving cognitive domain compared to smokers. Other cognitive domains were not different between the groups.
(18)	Cross-sectional	No control for last cigarette	↓ cognition Current smokers with SZ or bipolar disorder had worse composite cognitive function compared to non-smokers.
(19)	Cross-sectional	No control for last cigarette	= cognition No significant differences in cognitive outcomes between smokers and non-smokers with first-episode SZ
(23)	Prospective human laboratory study	Deprived of cigarettes for 2 h and given either nicotine or placebo-containing gum	↓ cognition Attention was significantly improved in non-smokers compared to smokers with SZ after nicotine administration.
(24)	Cross-sectional	Last cigarette an hour before testing, cognition administered 2 h in, allowed smoke breaks with 30 min interval before re-initiating cognitive testing	↓ cognition Visual learning significantly improved in non-smokers compared to smokers.
(25)	Cross-sectional	Frequent smoke breaks (smokers never abstinent for >30 min)	↑ cognition Sustained attention, processing speed, response inhibition were significantly improved in smokers compared to non-smokers with SZ. No differences in non-psychiatric controls.
(26)	Cross-sectional	Frequent smoke breaks (smokers never abstinent for >30 min)	↑ cognition Verbal memory was significantly increased in smokers compared to non-smokers with SZ.
(27)	Cross-sectional	No control for last cigarette	↑ cognition Processing speed, spatial working memory, and visual learning was significantly improved in smokers compared to non-smokers with SZ.
(28)	RCT of haloperidol x nicotine	Overnight abstinence with randomized dose of nicotine patches	↑ cognition Nicotine lead to a dose-related reversal of haloperidol-induced cognitive impairments in memory and reaction time.
(29)	Placebo controlled crossover for cigarettes and nicotine nasal spray in current smokers	Administration of nicotine nasal spray or placebo nasal spray, and high nicotine cigarette and denicotinized cigarette.	↑ cognition Nicotine in nasal spray lead to significant improvement on a spatial organization task, verbal memory, and reaction time in SZ. Both cigarettes lead to improvement on spatial organization task.
(30)	Placebo controlled crossover with nicotine and placebo patch	Withdrawn from tobacco and given nicotine patch or placebo patch	↑ cognition Improved performance on n-back (working memory and selective attention) task in SZ smokers vs. non-smokers and worsened performance in control smokers vs. non-smokers
(31)	Cross sectional–3 conditions	3 test conditions—baseline, overnight abstinence, and 1 h after reinstatement with no more than 15 min smoking deprivation	↑ cognition Impaired visuospatial working memory (VSWM) during overnight abstinence in SZ, improved VSWM and CPT upon reinstatement in SZ.
(32)	Cross sectional–3 conditions	3 test conditions—baseline, overnight abstinence, and 3 h nicotine patch	↑ cognition Reaction time was significantly increased in the nicotine patch condition and worse in the abstinence condition in SZ.
(33)	Cross sectional–2 conditions	2 test conditions—after overnight abstinence, normal smoking behavior (No control for last cigarette)	↑ cognition VSWM was significantly increased in the smokers with SZ compared to healthy controls
(34)	Cross sectional	No control for last cigarette	↑ cognition Divided attention was significantly increased in the smoking condition and worse in the abstinence condition in SZ.