Visual memory in methamphetamine-dependent individuals: deficient strategic control of encoding and retrieval.
OBJECTIVE
Chronic use of methamphetamine (MA) has moderate effects on neurocognitive functions associated with frontal systems, including the executive aspects of verbal episodic memory. Extending this literature, the current study examined the effects of MA on visual episodic memory with the hypothesis that a profile of deficient strategic encoding and retrieval processes would be revealed for visuospatial information (i.e., simple geometric designs), including possible differential effects on source versus item recall.


METHODS
The sample comprised 114 MA-dependent (MA+) and 110 demographically-matched MA-nondependent comparison participants (MA-) who completed the Brief Visuospatial Memory Test-Revised (BVMT-R), which was scored for standard learning and memory indices, as well as novel item (i.e., figure) and source (i.e., location) memory indices.


RESULTS
Results revealed a profile of impaired immediate and delayed free recall (p<0.05) in the context of preserved learning slope, retention, and recognition discriminability in the MA+ group. The MA+ group also performed more poorly than MA- participants on Item visual memory (p<0.05) but not Source visual memory (p>0.05), and no group by task-type interaction was observed (p>0.05). Item visual memory demonstrated significant associations with executive dysfunction, deficits in working memory, and shorter length of abstinence from MA use (p<0.05).


CONCLUSIONS
These visual memory findings are commensurate with studies reporting deficient strategic verbal encoding and retrieval in MA users that are posited to reflect the vulnerability of frontostriatal circuits to the neurotoxic effects of MA. Potential clinical implications of these visual memory deficits are discussed.
Department of Psychiatry, University of California San Diego, San Diego, CA 92103, USA. eemorgan@ucsd.edu
Erin E
EE
Morgan
Steven P
SP
Woods
Amelia J
AJ
Poquette
Ofilio
O
Vigil
Robert K
RK
Heaton
Igor
I
Grant
D000328:Adult; D019969:Amphetamine-Related Disorders / Q000503:physiopathology*; D016022:Case-Control Studies; D000697:Central Nervous System Stimulants / Q000009:adverse effects*; D005260:Female; D006801:Humans; D013287:Illicit Drugs / Q000009:adverse effects*; D008297:Male; D008568:Memory / Q000187:drug effects*; D061212:Memory, Episodic; D011939:Mental Recall / Q000187:drug effects*; D008694:Methamphetamine / Q000009:adverse effects*; D008875:Middle Aged; D009483:Neuropsychological Tests; D021641:Recognition, Psychology
D000697:Central Nervous System Stimulants; D013287:Illicit Drugs; D008694:Methamphetamine