Studies have shown that the patient's adjustment can  be deeply impacted by mild impairments in functions such as short-term memory.  The extra effort, vigilance, and concentration needed to compensate for such mild deficits result in an enormous fatiguing effect.  Such an effort produces a continuous drain on energy levels and results in chronic fatigue. Intellectual functions such as short-term memory tend to deteriorate as fatigue increases.  Such practices  give rise to a vicious cycle that to leads feelings of inadequacy, discouragement, irritability and depression.

  -- Source --   Neuropsychological Assessment, 2nd  Ed., 1983,  by Muriel D. Lezak