Effect of Single Dose Intranasal Insulin On Cognitive Function

Primary outcomes

1. Improvement in Cognitive Function- HVLT Immediate Recall Total (Number)

   Time frame: pretreatment= in the morning; postreatment= in the afternoon, 30 minutes after intranasal spray administration

   Subjects performed the HVLT Immediate Recall Task. For this task, participants were read aloud a list of 12 words from three taxonomic categories. Participants were read the list three separate times, and after each reading were immediately asked to recall as many words from the list as they could. The number of words recalled successfully was measured before and after intranasal treatment. Values below represent posttreatment performance minus pretreatment performance.

2. Improvement in Cognitive Function- HVLT-Delayed Recall (Number)

   Time frame: pretreatment= in the morning; postreatment= in the afternoon, 30 minutes after intranasal spray administration

   Subjects performed the HVLT word recall task after a 20-minute delay before and after intranasal treatment. In the HVLT delayed recall task, participants were asked to recall the same list of 12 words dictated in the immediate recall task 20 minutes after the completion of the immediate recall task. Words successfully recalled after the 20-minute delay were measured. Values below represent posttreatment performance minus pretreatment performance.

3. CPT d Score

   Time frame: pretreatment= in the morning; postreatment= in the afternoon, 30 minutes after intranasal spray administration

   Subjects performed a computer-based test designed to measure sustained attention (attention to a specific stimuli over a period of several minutes) before and after intranasal treatment. During this test, participants respond as quickly as possible to any consecutive presentation of identical stimuli on the computer screen. The stimuli (2, 3, and 4-digit targets) were presented with increasing cognitive load in successive blocks. Correct responses, responses made to the second of 2 identical stimuli presented in a row, were scored as hits. False alarms were also recorded. The "d prime score" is a score given to each participant on a scale of 0.0- 1.0 in which discrimination sensitivity is measured. A score of zero equates to no sensitivity, whereas a score of 1.0 equates to perfect sensitivity. Values below represent postreatment performance minus pretreatment performance.

4. Improvement in Cognitive Function- CPT Hits Rate (Proportion)

   Time frame: pretreatment= in the morning; postreatment= in the afternoon, 30 minutes after intranasal spray administration

   Subjects performed a computer-based test designed to measure sustained attention before and after intranasal treatment. The task is described in the previous outcome measure ("CPT d score"). Hits rate refers to each participant's ability to correctly respond to two consecutive target presentations (i.e. correct responses). Hits rate was measured as a proportion of overall attempts (0= no hits, 1.0= 100% accuracy on hits). Values below represent posttreatment performance minus pretreatment performance.

5. Improvement in Cognitive Function- CPT Reaction Time of Hits (Milliseconds)

   Time frame: pretreatment= in the morning; postreatment= in the afternoon, 30 minutes after intranasal spray administration

   Subjects performed a computer-based test designed to measure sustained attention before and after intranasal treatment. The task is described in detail in a previous outcome measure ("CPT d score"). Reaction time of hits refers to the average time each participant took to correctly respond to a stimuli in milliseconds. Values below represent posttreatment performance minus pretreatment performance.

6. Improvement in Cognitive Function- CPT False Alarm Rate (Proportion)

   Time frame: pretreatment= in the morning; postreatment= in the afternoon, 30 minutes after intranasal spray administration

   Subjects performed a computer-based test designed to measure sustained attention before and after intranasal treatment. The task is described in detail in a previous outcome measure ("CPT d score"). False alarm rate refers to the proportion of overall attempts that were characterized as incorrect responses (responses to two non-identical targets). Values below represent posttreatment performance minus pretreatment performance.